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Below you can read some scientific articles about different areas:
ACCOMODATION
TREATMENT OF ACCOMMODATIVE DYSFUNCTION IN CHILDREN: RESULTS FROM A RANDOMIZED CLINICAL TRIAL.
Abstract
PURPOSE:
To report the effectiveness of various forms of vision therapy/orthoptics in improving accommodative amplitude and facility in children with symptomatic convergence insufficiency (CI) and co-existing accommodative dysfunction.
METHODS:
In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic CI were assigned to one of four treatments. Of the enrolled children, 164 (74%) had accommodative dysfunction; 63 (29%) had a decreased amplitude of accommodation with respect to age, 43 (19%) had decreased accommodative facility, and 58 (26%) had both. Analysis of variance models were used to compare mean accommodative amplitude and accommodative facility for each treatment group after 4, 8, and 12 weeks of treatment.
RESULTS:
After 12 weeks of treatment, the increases in amplitude of accommodation [office-based vergence/accommodative therapy with home reinforcement group (OBVAT) 9.9 D, home-based computer vergence/accommodative therapy group (HBCVAT+) 6.7 D, and home-based pencil push-up therapy group (HBPP) 5.8 D] were significantly greater than in the office-based placebo therapy (OBPT) group (2.2 D) (p-values ≤0.010). Significant increases in accommodative facility were found in all groups (OBVAT: 9 cpm, HBCVAT+: 7 cpm, HBPP: 5 cpm, OBPT: 5.5 cpm); only the improvement in the OBVAT group was significantly greater than that found in the OBPT group (p = 0.016). One year after completion of therapy, reoccurrence of decreased accommodative amplitude was present in only 12.5% and accommodative facility in only 11%.
CONCLUSIONS:
Vision therapy/orthoptics is effective in improving accommodative amplitude and accommodative facility in school-aged children with symptomatic CI and accommodative dysfunction.
EFFECT OF VISION THERAPY ON ACCOMMODATION IN MYOPIC CHINESE CHILDREN.
Abstract
Introduction. We evaluated the effectiveness of office-based accommodative/vergence therapy (OBAVT) with home reinforcement to improve accommodative function in myopic children with poor accommodative response. Methods. This was a prospective unmasked pilot study. 14 Chinese myopic children aged 8 to 12 years with at least 1 D of lag of accommodation were enrolled. All subjects received 12 weeks of 60-minute office-based accommodative/vergence therapy (OBAVT) with home reinforcement. Primary outcome measure was the change in monocular lag of accommodation from baseline visit to 12-week visit measured by Shinnipon open-field autorefractor. Secondary outcome measures were the changes in accommodative amplitude and monocular accommodative facility. Results. All participants completed the study. The lag of accommodation at baseline visit was 1.29 ± 0.21 D and it was reduced to 0.84 ± 0.19 D at 12-week visit. This difference (-0.46 ± 0.22 D; 95% confidence interval: -0.33 to -0.58 D) is statistically significant (p < 0.0001). OBAVT also increased the amplitude and facility by 3.66 ± 3.36 D (p = 0.0013; 95% confidence interval: 1.72 to 5.60 D) and 10.9 ± 4.8 cpm (p < 0.0001; 95% confidence interval: 8.1 to 13.6 cpm), respectively. Conclusion. Standardized 12 weeks of OBAVT with home reinforcement is able to significantly reduce monocular lag of accommodation and increase monocular accommodative amplitude and facility. A randomized clinical trial designed to investigate the effect of vision therapy on myopia progression is warranted.
EFFECT OF VISION THERAPY ON ACCOMODATIVE LAG IN MYOPIC CHILDREN: A RANDOMIZED CLINICAL TRIAL.
Abstract
SIGNIFICANCE:
Accommodative dysfunction has been suggested to be related to the development and progression of myopia. Office-based accommodative/vergence therapy (OBAVT) improved accommodative facility in Chinese myopic children, but it is unclear if such improvement has a role in decreasing myopic progression.
PURPOSE:
The purpose of this study was to compare the effects of OBAVT with home reinforcement and office-based placebo therapy (OBPT) as a treatment to improve accommodative functions (i.e., lag, amplitude, and facility) in myopic children with poor accommodative accuracy.
METHODS:
This was a prospective, single-masked, randomized clinical trial. Thirty-four Chinese children 8 to 12 years old with myopia and at least 1 diopter of lag of accommodation measured by autorefraction were enrolled. The participants were randomly assigned to the OBAVT or OBPT group. The primary outcome measure was the change in the monocular lag of accommodation from the baseline visit to the 13-week visit measured by a Shin-Nippon open-field autorefractor. Secondary outcome measures were changes in accommodative amplitude and monocular accommodative facility.
RESULTS:
A total of 33 participants completed the study. After 12 weeks of treatment, there were significant improvements in the lag of accommodation in both the OBAVT and OBPT groups (OBAVT: -0.30 ± 0.29 diopters [P < .001; Cohen’s d effect size, 1.29]; OBPT: -0.24 ± 0.30 diopters [P = .005; Cohen’s d effect size, 1.24]). There was no statistically significant difference between the improvements in the two groups (P = .50). There was statistically significant improvement in monocular accommodative facility only in the OBAVT group (OBAVT: 7.7 ± 4.7 cycles per minute [P < .001; Cohen’s d effect size, 2.20]; OBPT: 1.9 ± 4.4 cycles per minute [P = .072]). The change in the OBAVT group was statistically significantly larger than that in the OBPT group (P < .001).
CONCLUSIONS:
Office-based accommodative/vergence therapy was no more effective than OBPT in reducing the lag of accommodation in children 8 to 12 years old with low to moderate myopia. It did improve accommodative facility in Chinese myopic children, but it is unclear if such an improvement has a role in decreasing myopic progression.
Abstract
BACKGROUND:
For nearly 75 years, optometric vision therapy has been an important mode of therapy for both children and adults who manifested a range of nonstrabismic accommodative and vergence disorders.
METHODS:
In this article, the scientific basis for, and efficacy of, optometric vision therapy in such patients will be discussed. Using bio-engineering models of the oculomotor system as the conceptual framework, emphasis will be focused on studies that used objective recording techniques to directly assess therapeutically related changes in oculomotor responsivity.
RESULTS AND CONCLUSIONS:
The findings clearly support the validity of optometric vision therapy. Furthermore, the results are consistent with the tenets of general motor learning.
Abstract
The primary aim of this project was to study the effect of flip lens-training on the accommodative function in a group of children with accommodative dysfunction and subjective symptoms such as asthenopia, headache, blurred vision, and avoidance of near activity. We also wanted to measure the accommodative facility among the children in comparison with a control group. Another aim of the study was whether flip lens-training increased accommodative facility, and to find out if it also had a positive effect on their asthenopia and related problems also in long term. Following the training period the accommodative facility and accommodative function significantly increased and two years after finishing the training period no child had regained any subjective symptoms and the objective findings were almost the same as at the end of facility training period. These results suggest that accommodative facility training is an efficient method built on loss of symptoms among children with accommodative infacility.
Abstract
The effects of accommodative facility training were evaluated by comparing training with plano lenses and +/-2.00 D lens flipper sets. Thirteen children with symptoms and signs of accommodative dysfunction were included in the study. Seven started with 2 weeks of plano lens training before proceeding to traditional dioptric flipper training; later, one patient from this group was lost to follow-up. The remaining six children used powered flipper training from the start. The positive (PRA) and negative relative accommodation (NRA) were examined every second week. During the initial training period both the PRA and the NRA decreased in the sham treatment group (P = 0.010 and P= 0.102, respectively), while the PRA and the NRA increased during the dioptric training in both groups (P = 0.102 and P = 0.033, respectively). The result of this study indicates that accommodative facility training has a real effect on the amplitude of relative accommodation in patients with impaired relative accommodation.
EFFECT OF OCULOMOTOR REHABILITATION ON ACCOMODATIVE RESPOSIVITY IN MILD TRAUMATIC BRAIN INJURY.
Abstract
Accommodative dysfunction is a common oculomotor sequelae of mild traumatic brain injury (mTBI). This study evaluated a range of dynamic (objective) and static (subjective) measures of accommodation in 12 nonstrabismic individuals with mTBI and near vision-related symptoms before and after oculomotor training (OMT) and placebo (P) training (6 wk, two sessions per week, 3 h of training each). Following OMT, the dynamics of accommodation improved markedly. Clinically, there was a significant increase in the maximum accommodative amplitude both monocularly and binocularly. In addition, the near vision symptoms reduced along with improved visual attention. None of the measures were found to change significantly following P training. These results provide evidence for a significant positive effect of the accommodatively based OMT on accommodative responsivity. Such improvement is suggestive of oculomotor learning, demonstrating considerable residual brain-visual system plasticity in the adult compromised brain.
VISUAL TRAINING IMPROVES UNDERWATER VISION IN CHILDREN.
Abstract
Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation.
BINOCULARITY
RANDOMIZED CLINICAL TRIAL OF TREATMENTS FOR SYMPTOMATIC CONVERGENCE INSUFFICIENCY IN CHILDREN.
Abstract
OBJECTIVE:
To compare home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), and office-based placebo therapy with home reinforcement (OBPT) as treatments for symptomatic convergence insufficiency.
METHODS:
In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic convergence insufficiency were assigned to 1 of 4 treatments.
MAIN OUTCOME MEASURES:
Convergence Insufficiency Symptom Survey score after 12 weeks of treatment. Secondary outcomes were near point of convergence and positive fusional vergence at near.
RESULTS:
After 12 weeks of treatment, the OBVAT group’s mean Convergence Insufficiency Symptom Survey score (15.1) was statistically significantly lower than those of 21.3, 24.7, and 21.9 in the HBCVAT+, HBPP, and OBPT groups, respectively (P < .001). The OBVAT group also demonstrated a significantly improved near point of convergence and positive fusional vergence at near compared with the other groups (P <or= .005 for all comparisons). A successful or improved outcome was found in 73%, 43%, 33%, and 35% of patients in the OBVAT, HBPP, HBCVAT+, and OBPT groups, respectively.
CONCLUSIONS:
Twelve weeks of OBVAT results in a significantly greater improvement in symptoms and clinical measures of near point of convergence and positive fusional vergence and a greater percentage of patients reaching the predetermined criteria of success compared with HBPP, HBCVAT+, and OBPT. Application to Clinical Practice Office-based vergence accommodative therapy is an effective treatment for children with symptomatic convergence insufficiency.
A RANDOMIZED CLINICAL TRIAL OF TREATMENTS FOR CONVERGENCE INSUFFICIENCY IN CHILDREN.
Abstract
OBJECTIVE:
To compare vision therapy/orthoptics, pencil push-ups, and placebo vision therapy/orthoptics as treatments for symptomatic convergence insufficiency in children 9 to 18 years of age.
METHODS:
In a randomized, multicenter clinical trial, 47 children 9 to 18 years of age with symptomatic convergence insufficiency were randomly assigned to receive 12 weeks of office-based vision therapy/orthoptics, office-based placebo vision therapy/orthoptics, or home-based pencil push-ups therapy.
MAIN OUTCOME MEASURES:
The primary outcome measure was the symptom score on the Convergence Insufficiency Symptom Survey. Secondary outcome measures were the near point of convergence and positive fusional vergence at near.
RESULTS:
Symptoms, which were similar in all groups at baseline, were significantly reduced in the vision therapy/orthoptics group (mean symptom score decreased from 32.1 to 9.5) but not in the pencil push-ups (mean symptom score decreased from 29.3 to 25.9) or placebo vision therapy/orthoptics groups (mean symptom score decreased from 30.7 to 24.2). Only patients in the vision therapy/orthoptics group demonstrated both statistically and clinically significant changes in the clinical measures of near point of convergence (from 13.7 cm to 4.5 cm; P < .001) and positive fusional vergence at near (from 12.5 prism diopters to 31.8 prism diopters; P < .001).
CONCLUSIONS:
In this pilot study, vision therapy/orthoptics was more effective than pencil push-ups or placebo vision therapy/orthoptics in reducing symptoms and improving signs of convergence insufficiency in children 9 to 18 years of age. Neither pencil push-ups nor placebo vision therapy/orthoptics was effective in improving either symptoms or signs associated with convergence insufficiency.
Abstract
PURPOSE:
The purpose of this article is to compare vision therapy/orthoptics, pencil pushups, and placebo vision therapy/orthoptics as treatments for symptomatic convergence insufficiency in adults 19 to 30 years of age.
METHODS:
In a randomized, multicenter clinical trial, 46 adults 19 to 30 years of age with symptomatic convergence insufficiency were randomly assigned to receive 12 weeks of office-based vision therapy/orthoptics, office-based placebo vision therapy/orthoptics, or home-based pencil pushups. The primary outcome measure was the symptom score on the Convergence Insufficiency Symptom Survey. Secondary outcome measures were the near point of convergence and positive fusional vergence at near.
RESULTS:
Only patients in the vision therapy/orthoptics group demonstrated statistically and clinically significant changes in the near point of convergence (12.8 cm to 5.3 cm, p = 0.002) and positive fusional vergence at near (11.3Delta to 29.7Delta, p = 0.001). Patients in all three treatment arms demonstrated statistically significant improvement in symptoms with 42% in office-based vision therapy/orthoptics, 31% in office-based placebo vision therapy/orthoptics, and 20% in home-based pencil pushups achieving a score <21 (our predetermined criteria for elimination of symptoms) at the 12-week visit.
DISCUSSION:
In this study, vision therapy/orthoptics was the only treatment that produced clinically significant improvements in the near point of convergence and positive fusional vergence. However, over half of the patients in this group (58%) were still symptomatic at the end of treatment, although their symptoms were significantly reduced. All three groups demonstrated statistically significant changes in symptoms with 42% in office-based vision therapy/orthoptics, 31% in office-based placebo vision therapy/orthoptics, and 20% in home-based pencil push-ups meeting our criteria for elimination of symptoms.
NON-SURGICAL INTERVENTIONS FOR CONVERGENCE INSUFFICIENCY.
Abstract
BACKGROUND:
Convergence insufficiency is a common eye muscle co-ordination problem in which the eyes have a strong tendency to drift outward (exophoria) when reading or doing close work. Symptoms may include eye strain, headaches, double vision, print moving on the page, frequent loss of place when reading, inability to concentrate, and short attention span.
OBJECTIVES:
To systematically assess and synthesize evidence from randomized controlled trials (RCTs) on the effectiveness of non-surgical interventions for convergence insufficiency.
SEARCH STRATEGY:
We searched The Cochrane Library, MEDLINE, EMBASE, Science Citation Index, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov ) on 7 October 2010. We manually searched reference lists and optometric journals.
SELECTION CRITERIA:
We included RCTs examining any form of non-surgical intervention against placebo, no treatment, sham treatment, or each other.
DATA COLLECTION AND ANALYSIS:
Two authors independently assessed eligibility, risk of bias, and extracted data. We performed meta-analyses when appropriate.
MAIN RESULTS:
We included six trials (three in children, three in adults) with a total of 475 participants. We graded four trials at low risk of bias.Evidence from one trial (graded at low risk of bias) suggests that base-in prism reading glasses was no more effective than placebo reading glasses in improving clinical signs or symptoms in children. Evidence from one trial (graded at high risk of bias) suggests that base-in prism glasses using a progressive addition lens design was more effective than progressive addition lens alone in decreasing symptoms in adults. At three weeks of therapy, the mean difference in Convergence Insufficiency Symptoms Survey (CISS) score was -10.24 points (95% confidence interval (CI) -15.45 to -5.03). Evidence from two trials (graded at low risk of bias) suggests that outpatient (or office-based as used in the US) vision therapy/orthoptics was more effective than home-based convergence exercises (or pencil push-ups as used in the US) in children. At 12 weeks of therapy, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 3.99 cm (95% CI 2.11 to 5.86), 13.13 diopters (95% CI 9.91 to 16.35), and 9.86 points (95% CI 6.70 to 13.02), respectively.In a young adult population, evidence from one trial (graded at low risk of bias) suggests outpatient vision therapy/orthoptics was more effective than home-based convergence exercises in improving positive fusional vergence at near (7.7 diopters, 95% CI 0.82 to 14.58), but not the other outcomes.Evidence from one trial (graded at low risk of bias) comparing four interventions, also suggests that outpatient vision therapy/orthoptics was more effective than home-based computer vision therapy/orthoptics in children. At 12 weeks, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 2.90 cm (95% CI 0.96 to 4.84), 7.70 diopters (95% CI 3.94 to 11.46), and 8.80 points (95% CI 5.26 to 12.34), respectively. Evidence was less consistent for other pair-wise comparisons.
AUTHORS’ CONCLUSIONS:
Current research suggests that outpatient vision therapy/orthoptics is more effective than home-based convergence exercises or home-based computer vision therapy/orthoptics for children. In adult population, evidence of the effectiveness of various non-surgical interventions is less consistent.
IMPROVEMENT IN ACADEMIC BEHAVIORS AFTER SUCCESSFUL TREATMENT OF CONVERGENCE INSUFFICIENCY.
Abstract
PURPOSE:
To determine whether treatment of symptomatic convergence insufficiency (CI) has an effect on Academic Behavior Survey (ABS) scores.
METHODS:
The ABS is a six-item survey developed by the Convergence Insufficiency Treatment Trial Group that quantifies the frequency of adverse school behaviors and parental concern about school performance on an ordinal scale from 0 (never) to 4 (always) with total scores ranging from 0 to 24. The ABS was administered at baseline and after 12 weeks of treatment to the parents of 218 children aged 9 to 17 years with symptomatic CI, who were enrolled in the Convergence Insufficiency Treatment Trial and randomized into (1) home-based pencil push-ups; (2) home-based computer vergence/accommodative therapy and pencil push-ups; (3) office-based vergence/accommodative therapy with home reinforcement; and (4) office-based placebo therapy with home reinforcement. Participants were classified as successful (n = 42), improved (n = 60), or non-responder (n = 116) at the completion of 12 weeks of treatment using a composite measure of the symptom score, nearpoint of convergence, and positive fusional vergence. Analysis of covariance methods were used to compare the mean change in ABS between response to treatment groups while controlling for the ABS score at baseline.
RESULTS:
The mean ABS score for the entire group at baseline was 12.85 (SD = 6.3). The mean ABS score decreased (improved) in those categorized as successful, improved, and non-responder by 4.0, 2.9, and 1.3 points, respectively. The improvement in the ABS score was significantly related to treatment outcome (p < 0.0001), with the ABS score being significantly lower (better) for children who were successful or improved after treatment as compared to children who were non-responders (p = 0.002 and 0.043, respectively).
CONCLUSIONS:
A successful or improved outcome after CI treatment was associated with a reduction in the frequency of adverse academic behaviors and parental concern associated with reading and school work as reported by parents.
EFFECTIVENESS OF VISION THERAPY IN SCHOOL CHILDREN WITH SYMPTOMATIC CONVERGENCE INSUFFICIENCY.
Abstract
PURPOSE:
To determine the effectiveness of vision therapy among Korean elementary school children with convergence insufficiency.
METHODS:
A total of 235 elementary schoolchildren, 10.13 ± 2.45 years of age, were subjected to thorough eye examination including binocular vision testing. Of them, 32 individuals with symptomatic convergence insufficiency without strabismus, amblyopia, and ocular disease were chosen to receive vision therapy via brock string, barrel card, mirror stereoscope, prism goggles, and aperture rule for a duration of 8 weeks.
RESULTS:
The results showed that most of the participants had severe problems in near point of convergence. After the vision therapy, the average near point of convergence improved by approximately 5.48 ± 0.96 cm in all participants. Moreover, vision therapy had an effect on increasing near positive fusional vergence and decreasing exophoria. Negative relative accommodation improved to 2.54 ± 0.51 and positive relative accommodation improved to -3.10 ± 1.08 diopters. After treatment, near phoria was 4.19 ± 1.66 and distance phoria was 1.61 ± 0.71 prism diopters.
CONCLUSION:
Among convergence insufficiency symptoms, the following improved in particular: near point of convergence, exophoria, and near positive fusional vergence. These findings suggest that vision therapy is very effective to recover from symptomatic convergence insufficiency.
Abstract
SIGNIFICANCE:
This first report of the use of objective measures of disparity vergence as outcome measures for symptomatic convergence insufficiency in children provides additional information that is not accessible with clinical tests. The study results also demonstrate that objective measures of vergence could be used in future randomized clinical trials of binocular vision disorders with children.
PURPOSE:
This study was designed to evaluate changes in objective measures of disparity vergence after office-based vergence/accommodative therapy (OBVAT) for convergence insufficiency in children 12 to 17 years old.
METHODS:
In this prospective trial, we recruited 10 participants with normal binocular vision and 12 with convergence insufficiency. All participants with convergence insufficiency were treated with 12 weeks of OBVAT. The primary outcome measure was average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence included time to peak velocity, latency, and accuracy. Changes in clinical measures (near point of convergence, positive fusional vergence at near) and symptoms were evaluated.
RESULTS:
There was a statistically significant increase in peak velocity and more accurate response amplitude to 4° symmetrical convergence step stimuli after OBVAT compared with baseline measurements. Near point of convergence, positive fusional vergence, and symptoms also statistically significantly improved after OBVAT. Ten of the 12 participants met clinical success criteria.
CONCLUSIONS:
In this prospective study on the treatment of symptomatic convergence insufficiency in children in which both clinical and objective eye movement measurements were used to evaluate the results of treatment, significant changes were found in symptoms and both clinical and objective measures of disparity vergence after completion of OBVAT in children with symptomatic convergence insufficiency.
EFFICACY OF TREATMENT FOR CONVERGENCE INSUFFICIENCY USING VISION THERAPY.
Abstract
PURPOSE:
The purpose of this study was to determine if vision therapy (VT), as practised within the constraints of UK optometric practice, employing graded routine eye exercises, is as an effective method for treatment of convergence insufficiency (CI) as previously published data suggest. The study also evaluates the associated symptoms before and after therapy.
METHODS:
As many optometrists diagnose CI solely on the basis of near point of convergence (NPC) and treat only when symptoms are present (Letourneau et al., 1979; Rouse et al., 1997), in this study CI was defined as NPC of 10 cm or greater (either with or without the presence of asthenopic symptoms for near work) accompanied by exophoria greater at near than at distance. The effect of treatment by optometric vision therapy (OVT) on the NPC and number of symptoms was investigated for 92 patients by retrospectively reviewing the clinical records. Success was defined as the restoration of NPC to normal values and significant reduction in the presenting symptoms.
RESULTS:
The effect of treatment on the NPC was shown to be highly significant (t = 14.61, p < 0.001). Although treatment times were slightly longer, the success rates were higher than reported by other authors. Post-treatment values for NPC were: <10 cm (98.9%), <8.5 cm (95.7%) and <6.5 cm (80.4%). Longer treatment times were noted for patients who complained that the text appeared to move (chi2, p = 0.007).
CONCLUSION:
Vision therapy is an effective method for treatment of CI.
Abstract
PURPOSE:
This study examined the relationship between the near dissociated phoria and disparity vergence eye movements. Convergence insufficiency (CI) patients before vergence therapy were compared to: (1) the same patients after vergence therapy; and (2) binocularly normal controls (BNC).
METHODS:
Sixteen subjects were studied-twelve BNC and four with CI. Measurements from the CI subjects were obtained before and after 18 h of vergence eye movement therapy. The near dissociated phoria was measured using the flashed Maddox rod technique. Vergence responses were stimulated from 4° symmetrical disparity vergence step stimuli. The peak velocity of the vergence response and the magnitude of the fusion initiating component (FIC) from an independent component analysis (ICA) were calculated. A linear regression analysis was conducted studying the vergence peak velocity as a function of the near dissociated phoria where the Pearson correlation coefficient was computed.
RESULTS:
Before vergence therapy, the average with one standard deviation FIC magnitude of convergence responses from CI subjects was 0.29° ± 0.82 and significantly less than the FIC magnitude of 1.85° ± 0.84 for BNC (p < 0.02). A paired t-test reported that the FIC and near dissociated phoria before vergence therapy for CI subjects significantly increased to 1.49° ± 0.57 (p < 0.04) and became less exophoric to 3.5Δ ± 1.9 exo (p < 0.02) after vergence therapy. A significant correlation (r = 0.87; p < 0.01) was observed between the near dissociated phoria and the vergence ratio of convergence peak velocity divided by divergence peak velocity.
CONCLUSION:
The results have clinical translational impact in understanding the mechanism by which vergence therapy may be changing the vergence system leading to a sustained reduction in visual symptoms.
Vision therapy in adults with convergence Insufficiency: clinical and functional Magnetic resonance imaging measures.
Abstract
PURPOSE:
This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI).
METHODS:
Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects.
RESULTS:
Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated.
CONCLUSIONS:
Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes.
Abstract
SIGNIFICANCE:
Prior studies have demonstrated the effectiveness of vergence-accommodative therapy in the treatment of convergence insufficiency (CI). These results show the changes in brain activation following therapy through the use of functional magnetic resonance imaging (fMRI).
PURPOSE:
The purpose of this study was to investigate changes in brain activation following office-based vergence-accommodative therapy versus placebo therapy for CI using the blood oxygenation level-dependent signal from fMRI.
METHODS:
Adults (n = 7, aged 18 to 30 years) with symptomatic CI were randomized to 12 weeks of vergence-accommodative therapy (n = 4) or placebo therapy (n = 3). Vergence eye movements were performed during baseline and outcome fMRI scans.
RESULTS:
Before therapy, activation (z score ≥ 2.3) was observed in the occipital lobe and areas of the brain devoted to attention, with the largest areas of activation found in the occipital lobe. After vergence-accommodative therapy, activation in the occipital lobe decreased in spatial extent but increased in the level of activation in the posterior, inferior portion of the occipital lobe. A new area of activation appeared in the regions of the lingual gyrus, which was not seen after placebo therapy. A significant decrease in activation was also observed in areas of the brain devoted to attention after vergence-accommodative therapy and to a lesser extent after placebo therapy.
CONCLUSIONS:
Observed activation pre-therapy consistent with top-down processing suggests that convergence requires conscious effort in symptomatic CI. Decreased activation in these areas after vergence-accommodative therapy was associated with improvements in clinical signs such as fusional vergence after vergence-accommodative therapy. The increase in blood oxygen level-dependent response in the occipital areas following vergence-accommodative therapy suggests that disparity processing for both depth and vergence may be enhanced following vergence-accommodative therapy.
Abstract
OBJECTIVE:
To evaluate two cases of intermittent exotropia treated by vision therapy the efficacy of the treatment by complementing the clinical examination with a 3D videooculography to register and to evidence the potential applicability of this technology for such purpose.
METHODS:
We report the binocular alignment changes occurring after vision therapy in a woman of 36 years with an intermittent exotropia of 25 prism diopters at far and 18 PD at near and a child of 10 years with 8 PD of intermittent exotropia in primary position associated to 6 PD of left eye hypotropia. Both patients presented good visual acuity with correction in both eyes. Instability of ocular deviation was evident by VOG analysis, revealing also the presence of vertical and torsional components. Binocular vision therapy was prescribed and performed including different types of vergence, accommodation, and consciousness of diplopia training.
RESULTS:
After therapy, excellent ranges of fusional vergence and a to-the-nose near point of convergence were obtained.The 3D VOG examination confirmed the compensation of the deviation with a high level of stability of binocular alignment. Significant improvement could be observed after therapy in the vertical and torsional components that were found to become more stable. Patients were very satisfied with the outcome obtained by vision therapy.
CONCLUSION:
3D-VOG is a useful technique for providing an objective register of the compensation of the ocular deviation and the stability of the binocular alignment achieved after vision therapy in cases of intermittent exotropia, providing a detailed analysis of vertical and torsional improvements.
REDUCTION OF SYMPTOMS IN BINOCULAR ANOMALIES USING COMPUTERIZED HOME THERAPY-HTS.
Abstract
BACKGROUND:
Asthenopic symptoms often are associated with various accommodative/vergence disorders. Recent studies have found that symptoms associated with convergence insufficiency are reduced by in-office vision therapy with supplemental home therapy. No studies have used standardized symptom questionnaires to evaluate the effectiveness of either in-office or home-based vision therapy in binocular anomalies other than convergence insufficiency. This retrospective study was designed to evaluate the changes in symptoms using an automated, home computer vision therapy program (HTS) in accommodative/vergence disorders.
METHODS:
A retrospective study of 43 prepresbyopic patients who completed the HTS was performed. Before and immediately after treatment all patients in this study completed a 15-question symptom questionnaire (Convergence Insufficiency Symptom Survey). Treatment consisted of various accommodative and vergence activities.
RESULTS:
Initial symptoms scores on the scaled questionnaire were 32.8 (SD = 8.1); after therapy they were 20.6 (SD = 11.5). These changes were both clinically and statistically significant. Forty percent were «normalized» and 55% improved. Convergence amplitude improved from 22Delta to 53Delta after treatment, and divergence amplitudes improved from 15Delta to 25Delta. These findings were clinically significant. Lastly, more than 75% of the patients finished the program by 40 sessions (equivalent to 8 weeks).
CONCLUSION:
Automated vision therapy delivered by the HTS system improved convergence and divergence amplitudes with a concomitant reduction in symptoms. The HTS system should be used on those patients with symptoms associated with an accommodative/vergence anomaly when in-office vision therapy supplemented with home therapy is not practical.
DYSLEXIA
1. Eden GF, Stein JF, Wood HM, Wood, FB. Differences In Eye Movement And Reading Problems In Dyslexic And Normal Children. Vision Research 34 (10): 1345-1358, 1994.
It has been suggested that eye movement abnormalities seen in dyslexics are attributable to their language problems. In order to investigate this claim, we studied eye movements in dyslexic children during several non-reading tasks.
Dyslexic children were compared to normal and backward readers on measures of fixation, vergence amplitude, saccade and smooth pursuit. The results were compared to the children’s phonological ability. Dyslexic children (n = 26) had significantly worse eye movement stability during fixation of small targets tan normal children (n = 30). Vergence amplitudes were lower for dyslexics than for controls. A qualitative assessment of saccadic eye movements revealed that dyslexics exhibit fixation instability at the end of saccades. Assessment of smooth pursuit revealed poor smooth pursuit in the dyslexic group, particularly when pursuing a target moving from left to right. Dyslexic children also performed significantly worse than normal children on a test of phonological awareness (Pig Latin). Eye movement results were studied in the light of the findings on phonological awareness: dyslexics with small vergence amplitudes also always have poor phonemic awareness. However, poor fixation control is found in dyslexics with or without poor phonological ability. The backward Reading children performed similar to the dyslexics on all tests, suggesting that the deficiencies observed in this study are not specific to children with dyslexia.
The problems experienced by the children (revealed by a questionnaire) are in agreement with those measured in terms of eye movement recording sand phonemic awareness. Sex, handedness, IQ or the presence of attention déficit disorder (ADD) did not appear to influence the children’s performances on any of the eye movement tasks. The presence of oculomotor abnormalities in a nonreading task strongly suggest that the underlying deficit in the control of eye movements seen in dyslexics is not caused by language problems alone.
2. Fischer B, Hartnegg K. Instability Of Fixation In Dyslexia: Development – Deficits – Training. Optom Vis Dev 2009; 40: 221-228.
BACKGROUND: While eye movements as a necessary prerequisite for natural viewing become more and more important as a part of the neurological diagnostic evaluation, the utilization of fixation is not as well established. This paper discusses two different and independent types of instability of fixation which can only be recognized by recording and analyzing specific movements of the eyes that include: (i)binocular instability (slow movements of the two eyes with different velocities mostly of opposite sign) and (ii) simple instability (small involuntary conjugate saccades (intrusions) during periods of fixating a stationary fixation point).
METHODS: A prosaccade task with overlap conditions is utilized which requires periods of stationary fixation as well as saccades to a new stimulus target. This allows the quantitative determination of the appropriate variables.
RESULTS: The diagnostic data from children diagnosed with dyslexia are compared with those of age-matched control subjects. An optomotor therapy procedure with one eye covered reduced the binocular instability by 50%, while the simple instability was reduced by 20%.
CONCLUSION: The results indicate that the two types of fixation instability are independent from each other. Both may contribute to problems of visual processing of those with dyslexia and possible other learning problems.
1. Franklin, A, Sowden, P, Notman, L, Et. Al. Reduced Chromatic Discrimination In Children With Autism Spectrum Disorders. Dev Sci 2010:13;188-200.
Children with autism spectrum disorders often exhibit atypical perception. This paper investigated chromatic discrimination in children, of the same age and non-verbal cognitive ability, with autism spectrum disorders compared to children with typical development. Two experiments were performed.
Experiment one measured the chromatic discrimination of fourteen children with high functioning autism (HFA) and fourteen children, average age 14, with typical development (TD). Participants were given the Farnsworth-Munsell 100 hue test and an achromatic control test.
Experiment two measured the chromatic threshold of 34 children with high functioning autism and 33 children with typical development. Participants were shown a circle with a color boundary created by having a different color on each half of the circle. Participants were then asked which direction the color boundary was tilting, left or right. The chromatic difference between the two halves of the circle was increased or decreased based on participant responses to estimate the just-noticeable difference (JND). The same test was performed using a circle with different luminance on each half to assess the participants’ luminance threshold as a control measure.
Experiment one showed that the HFA group made more errors in chromatic discrimination than the TD group. Comparing normative test values, the HFA group performed at a level similar to children with typical development three years younger. Both groups made similar errors on the achromatic control test. Experiment two showed that chromatic thresholds were elevated for the HFA group compared to the TD group. There was no difference between groups on the luminance task. Both experiments show that reduced chromatic discrimination was caused by a general reduction in chromatic sensitivity instead of difficulty with either the red-green or blue-yellow color vision system. Moreover, because both groups performed equally well on all control testing, the study supports true differences in chromatic sensitivity rather than differences in overall testing ability. Therefore, this study provides evidence that chromatic discrimination is reduced in children with high functioning autism.
Study authors suggest that reduced chromatic discrimination could be due to atypical processing at the retinal level, over-functioning of neurons in V1, or reduced synchrony of V1 and other cortical areas.
2. Milne E, Griffiths H, Buckley A And Scope A. Vision In Children And Adolescents With Autistic Spectrum Disorder: Evidence For Reduced Convergence. J Autism Dev Disord 2009:39(7):965-75.
Prior studies have found conflicting results as to whether or not those affected by autistic spectrum disorder (ASD) experience a higher prevalence if vision disorders than the normal population. The “Vision in children and adolescents with autistic spectrum disorder: evidence for reduced convergence” study attempted to identify and better describe visual disturbances in ASD through a wide array of clinical tests. The study sample included 51 individuals with ASD and 44 typically developing (TD) controls with no history of developmental or neuropsychiatric disorders. The autistic group consisted of 25 with autistic disorder, 10 with Asperger’s disorder and 16 with PPD-NOS. Subtests from Weschler Abbreviated Scale of intelligence were used to determine low functioning ASD (LF ASD) individuals from high functioning ASD individuals (HF ASD).
The clinical and laboratory tests used to evaluate all subjects were administered by orthoptists and included visual acuity, stereoacuity, convergence/divergence (prism fusion range at near, near point of convergence [NPC]), presence of strabismus, ocular motility (pursuits), and optokinetic response (OKR). Each of these tests were performed once with the exception of NPC, which was completed three times.
The results were as follows-
Visual acuity: ASD group showed statistically poorer visual acuity in both right and left eyes compared to the TD group, however, the difference was not statistically significant.
Stereoacuity/Divergence/Ocular Motility/OKR: There were no statistical differences between the groups.
Convergence: Base out fusion range of ASD group was significantly lower than that of the TD group. The participants with ASD had significantly receded NPC compared to the TD group. All of the participants with reduced (>10.5cm) or abnormal (>12cm) NPC were low functioning.
Presence of strabismus: 10.6% of ASD individuals and 0% of TD group exhibited strabismus, a difference which was not statistically significant. Those subjects who were diagnosed with strabismus were not included in the testing/analysis.
The total incidence of abnormal vision was 11.4% in the TD group and 31.3% in the ASD group, indicating a significant difference between groups and visual system function. The authors note that the total incidence of abnormal vision experienced by those with ASD was lower than previously reported by various studies.
Additionally, the authors note that others have suggested that the receded NPC in ASD individuals may be explained by ASD participants’ becoming uncomfortable with a stranger close to their face, however the authors note that patients would likely have difficulties with base in/divergence measurements. As divergence measurements were normal, the findings provide support for a convergence abnormality in ASD.
3. Carmody DP, Kaplan M, Gaydos AM. Spatial Orientation Adjustments In Children With Autism In Hong Kong. Child Psychiatry Hum Dev. 2001 Spring;31(3):233-47.
Abnormal spatial orientation and body postures in children with autism often interfere with visual abilities to attend tasks and social interactions. Twenty-four children diagnosed with autism from Kowloon, Hong Kong were assessed for spatial orientation and spatial management abilities. Positive changes in spatial orientation were evident when the children wore ambient prism lenses and included changes in posture from slanted to erect. Adjustments in spatial management were evident in improved ball catching ability, a task requiring visual tracking and eye-hand coordination. The findings suggest that alterations to the sensory systems may lead to behavioral change in some children.
1. Altinas O. Etus V, Etus H, Et Al. Risk Of Strabismus And Amblyopia In Children With Hydrocephalus. Graefe’s Arch Clin Exp Ophthalmol 2005; 243: 1213-1217.
The purpose of this study was to establish whether children with hydrocephalus who were treated with operation have a higher probability of developing amblyopia or strabismus. Subjects included 25 children, ages 3 months to 18 years. Evaluation included visual acuity testing (tumbling “E” chart), determination of strabismus (alternating cover test and Hirschberg test) determination of refractive error (cycloplegic refraction), and ocular health assessment.
The study found that 40% of patient had a manifest strabismus and 20% had amblyogenic refractive errors. Eight percent (8%) of children had temporal disc pallor. Overall 56% were at risk for amblyopia (strabismic or refractive). Surgery increased the risk of amblyopia: 88% of those patients with shunt revision and 41% of those without shunt revision surgery had amblyopia. Similarly, 75% of children who underwent surgery, compared with 24% of those who had not had surgery were strabismic.
2. Ciuffreda Kj, Ludlum D, Thiagarajan P. Oculomotor Diagnostic Protocol For The Mtbi Population. Optometry 2011; 82:61-3.
As a result of increased numbers of soldiers returning from war with traumatic injuries and more thorough investigations of professional athletes post-concussion, there is a heightened awareness of TBI. Some of the ocular conditions resulting from a TBI are easily detected, while others, particularly in cases of mild TBI (mTBI), are more difficult to definitively diagnose. Patients who have had a mTBI often seem complicated and intimidating due to the vast array of visual, as well as behavioral, symptoms they report. These patients most often complain of difficulty reading, and also may complain of having difficulty functioning in visually complex environments, due to problems with scanning, tracking, and/or focusing. In addition, mTBI patients can experience diplopia, eye strain, vertigo, nausea, decreased visual memory, motion and light sensitivity, poor attention, and fatigue.
The most common oculomotor related issues occurring in mTBI patients are convergence insufficiency, accommodative insufficiency, and saccadic dysmetria. The diagnostic protocol for any TBI patient should consist of the tests which address vergence ranges, accommodation, and versions, including near point of convergence (NPC) break and recovery repeated several times, positive fusional vergence (PFV) ranges, vergence facility, horizontal dissociated and associated near phorias, accommodation convergence (AC/A) ratio, stereoacuity, accommodative amplitude and facility, negative and positive relative accommodation (NRA/PRA), fixational stability, saccades, pursuits, and the Developmental Eye Movement Test (DEM) or a Visagraph. Abnormalities in the findings from these tests occur in high frequency with patients who have mTBI. Once specific oculomotor and/or accommodative diagnoses are concluded, the patient can be successfully treated with vision therapy, including use of lenses and prisms. Tints can be utilized to decrease photosensitivity, and binasal occlusion may help in patients with motion sensitivity. Patients with visual field defects or difficulty with spatial localization may benefit from the use of prism.
3. Rowe F. The Profile Of Strabismus In Stroke Survivors. Eye. 2010; 24:682-5
AIM: To evaluate the profile of strabismus that occurs in stroke survivors and determine the relationship between site of stroke and symptom of diplopia.
METHODS: Prospective multi-centre cohort trial involving 16 recruiting centres (Vision In Stroke (VIS) Group). Standardised referral and investigation protocol used by local investigators. Each patient underwent assessment of ocular alignment, motility, and binocular vision. Results were evaluated with non-parametric statistical tests.
RESULTS: In all, 512 patients were recruited with a mean age of 69 years: SD 15 over a 2-year period (59% male patients, 41% female patients). Median duration from onset to vision assessment was 19 days (range 0-1140 days). About 19% of the patients had strabismus detected on orthoptic investigation after the onset of stroke. Of these strabismic patients 12.5% had strabismus that pre-existed the onset of stroke (that could be determined from case history). A total of 70% had strabismus associated with ocular motility abnormalities and 30% were in isolation. About 24% were associated with brain stem, cerebellar, thalamus or basal ganglia strokes, and 73% with cortical strokes. Around 36% complained of diplopia and the remainder had no symptoms related to their strabismus.
CONCLUSIONS: Strabismus was found to occur in 16.5% of patients after their stroke. Strabismus with diplopia was always associated with other ocular motility abnormalities, whereas strabismus without associated ocular motility abnormalities did not result in the symptom of diplopia.
1. Rouse M, Borsting E, Et Al. Academic Behaviors In Children With Convergence Insufficiency With And Without Parent-Reported ADHD. Optom Vis Sci. 2009 October; 86: 1169–1177.
PURPOSE: To determine if children with symptomatic Convergence Insufficiency (CI) without the presence of parent reported Attention Deficit Hyperactivity Disorder (ADHD) have higher scores on the academic behavior survey (ABS).
METHODS: The Academic Behavior Survey (ABS) is a 6-item survey that evaluates parent concern about school performance and the parents’ perceptions of the frequency of problem behaviors that their child may exhibit when reading or performing schoolwork (such as: difficulty completing work, avoidance, and inattention). Each item is scored on an ordinal scale from 0 (Never) to 4 (Always) with a total score ranging from 0 to 24. The survey was administered to the parents of 212 children 9-17 years old (mean age 11.8 yrs.) with symptomatic CI prior to enrolling into the Convergence Insufficiency Treatment Trial and to 49 children with normal binocular vision (NBV) (mean age 12.5 years). The parents reported whether the child had ADHD and this information was used to divide the symptomatic CI group into the CI with parent-report of ADHD or CI with parent-report of no ADHD groups.
RESULTS: Sixteen percent of the CI group and 6% of the NBV group were classified as ADHD by parental report. An analysis of covariance showed that the total ABS score for the symptomatic CI with parent-report of ADHD group (15.6) was significantly higher than the symptomatic CI with parent-report of no ADHD group (11.7, p=0.001) and the NBV group (8.7, p<0.0001). Children with CI with parent-report of no ADHD scored significantly higher on the ABS than the NBV group (p=0.036).
CONCLUSIONS: Children with symptomatic CI with parent-report of no ADHD scored higher on the ABS when compared to children with NBV. Children with parent-report of ADHD or related learning problems may benefit from comprehensive vision evaluation to assess for the presence of CI.
1. O’Connor Ar, Birch EE, Anderson A, Draper H. Relationship Between Binocular Vision, Visual Acuity, And Fine Motor Skills. Optom Vis Sci, 2010; 87: 942-7.
PURPOSE: The aims of this study were to analyze the relationship between the performance on fine motor skills tasks and peripheral and bifoveal sensory fusion, phasic and tonic motor fusion, the level of visual acuity (VA) in the poorer seeing eye, and the interocular VA difference.
METHODS: Subjects aged 12 to 28 years with a range of levels of binocular vision and VA performed three tasks: Purdue pegboard (number of pegs placed in 30 s), bead threading task (with two sizes of bead to increase the difficulty, time taken to thread a fixed number of beads), and a water pouring task (accuracy and time to pour a fixed quantity into five glass cylinders). Ophthalmic measures included peripheral (Worth 4 dot) and bifoveal (4 prism diopter) sensory fusion, phasic (prism bar) and tonic (Risley rotary prism) motor fusion ranges, and monocular VA.
RESULTS: One hundred twenty-one subjects with a mean age of 18.8 years were tested; 18.2% had a manifest strabismus. Performance on fine motor skills tasks was significantly better in subjects with sensory and motor fusion compared with those without for most tasks, with significant differences between those with and without all measures of fusion on the pegboard and bead task. Both the acuity in the poorer seeing eye (highest r value of all motor tasks = 0.43) and the interocular acuity difference were statistically significantly related to performance on the motor skill tasks.
CONCLUSIONS: Both sensory and motor fusion and good VA in both eyes are of benefit in the performance of fine motor skills tasks, with the presence of some binocular vision being beneficial compared with no fusion on certain sensorimotor tasks. This evidence supports the need to maximize fusion and VA outcomes.
1. Holmes JM, Leske DA, Hatt SR, Et Al. Stability Of Near Stereoacuity In Childhood Intermittent Exotropia. J Am Academy Ped Ophthalmol Strab 2011;15:462-7.
This study investigated near stereoacuity in children previously untreated for intermittent exotropia. Subjects included 95 children, ages 2-16, with intermittent exotropia. Stereoacuity was measured using the Preschool Randot (PSR) test for 2 successive examinations.
Results found that deterioration of intermittent exotropia was not frequent. When looking at 3 octave changes (3 doublings of stereoacuity value, such as 100 seconds to 800 seconds), 2% of children showed deterioration at 1 year and 7% at 2 years. When looking at 2 octave changes, 8% deteriorated at 1 year and 12% at 2 years. Although the sample size was small, all children who deteriorated and had subsequent stereopsis measurement, 71% improved to normal levels of stereoacuity.
The authors acknowledge that stereoacuity thresholds are variable, and deterioration of stereoacuity in intermittent exotropia at 1-2 years is infrequent. The authors do not recommend surgery for intermittent exotropia to prevent stereoacuity loss.
2. Silbert AL, Matta NS, Silbert DI. Incidence Of Strabismus And Amblyopia In Preverbal Children Previously Diagnosed With Pseudoesotropia. J Am Acad Ped Ophthal Strab 16:2:118-119
The purpose of this retrospective study was to determine how many children previously diagnosed with pseudoesotropia before 3 years of age actually developed strabismus or amblyopia.
Records from January 1, 2001 to February 26, 2010 were reviewed for all children diagnosed with pseudoesotropia seen by the same pediatric ophthalmologist. Inclusion criteria were normal refractive error and ocular alignment (according to American Association for Pediatric Ophthalmology and Strabismus criteria), and age <36 months at the time of the first exam. A comprehensive examination was performed on all children including cycloplegic refraction and a routine follow-up was scheduled in 6 months and again at 3 years of age.
Out of a total 1,249 charts coded as esotropia, 394 (32%) of them were coded as pseudoesotropia but only 306 met the inclusion criteria. Of the 306 children, 201 (66%) returned for their scheduled follow-up. A total of 25 children (12%) were found to have strabismus or refractive amblyopia at their follow-up: 20 children (10%) developed strabismus (15 esodeviation, 3 exodeviation, 1 duanes, 1 Prader-Willi syndrome + esotropia) and 5 children (2%) developed mild refractive amblyopia. Results of this study were similar to a previous study by Pritchard and Ellis that showed 12% of patients with pseudostrabismus develop a true strabismus.
The prevalence of strabismus in those diagnosed with pseudoesotropia (10%) is significantly higher than the prevalence in the general population (2.1- 3.3%). Hence, it is extremely important to perform closer follow-up on all children diagnosed with pseudoesotropia because of their higher risk to developing strabismus and amblyopia at a later age.
1. Barnes G., Lli X., Thompson B Et Al. Decreased Gray Matter Concentrations In The Lateral Geniculate Nuclei In Human Ambliopes. Invest Ophthal Vis Sci 2010; 51:1432-8
PURPOSE: In a group of humans with strabismic amblyopia, the relationship was examined between the structure and function of different brain regions. Three question were addressed: (1) Is the lateral geniculate nucleus (LGN) in humans with amblyopia structurally as well as functionally abnormal? (2) Do structural anomalies in the visual cortex correlate with the previously reported cortical functional losses? (3) Is there a link between the functional anomalies in the visual cortex and any structural anomalies in the geniculate?
METHODS: The structure was compared by using voxel-based morphometry (VBM) and the function by functional magnetic resonance imaging (fMRI).
RESULTS: The results showed that the geniculate is structurally abnormal in humans with strabismic amblyopia.
CONCLUSIONS: These findings add further weight to the role of the LGN in the cortical deficits exhibited in human strabismic amblyopes.
2. Niechwiej-Szwedo E, Goltz Hc, Chandrakumar M, Et Al. Effects Of Anisometropic Amblyopia On Visuomotor Behavior, I: Saccadic Eye Movements. Invest Ophthal Vis Sci 2010; 51:6348-6354
PURPOSE: Impairment of spatiotemporal visual processing is the hallmark of amblyopia, but its effects on eye movements during visuomotor tasks have rarely been studied. Here the authors investigate how visual deficits in anisometropic amblyopia affect saccadic eye movements.
METHODS: Thirteen patients with anisometropic amblyopia and 13 control subjects participated. Participants executed saccades and manual reaching movements to a target presented randomly 5° or 10° to the left or right of fixation in three viewing conditions: binocular, amblyopic, and fellow eye viewing. Latency, amplitude, and peak velocity of primary and corrective saccades were measured.
RESULTS: Initiation of primary saccades was delayed and more variable when patients viewed monocularly with their amblyopic eye. During binocular viewing, saccadic latency exhibited increased variability and no binocular advantage in patients (i.e., mean latency was similar to that during fellow eye viewing). Mean amplitude and peak velocity of primary saccades were comparable between patients and control subjects; however, patients exhibited greater variability in saccade amplitude. The frequency of corrective saccades was greater when patients viewed with their fellow eye than it was with binocular or amblyopic eye viewing. Latency, amplitude, and peak velocity of corrective saccades in patients were normal in all viewing conditions.
CONCLUSIONS: Saccades had longer latency and decreased precision in amblyopia. Once saccades were initiated, however, the dynamics of saccades were not altered. These findings suggest that amblyopia is associated with slower visual processing in the afferent (sensory) pathway rather than a deficit in the efferent (motor) pathway of the saccadic system.
3. Kanonidou E, Proudlock Fa, Gottlob I. Reading Strategies In Mild To Moderate Strabismic Amblyopia: An Eye Movement Investigation. Invest Ophthal Vis Sci. 2010; 51:3502-3508.
The purpose of this study was to evaluate, the oculomotor characteristics associated with decreased reading performance in adult strabismic amblyopia during both monocular and binocular reading.
Twenty adults with unilateral strabismic amblyopia were compared to a control group of twenty normal adult volunteers. The subjects were required to silently read paragraphs of continuous text while their gaze position was measured with an infrared, video-based pupil-tracking system. Two comparisons were made during monocular reading. The amblyopic eye was compared to the nondominant eye of the control subjects while the nonamblyopic eye was compared to the dominant eye of the control subjects. A comparison between amblyopes and control subjects was also made under binocular reading conditions.
Fixation duration, mean reading speed, number of progressive and regressive saccades per line and saccadic amplitude (of progressive saccades) were estimated. Mean reading speeds were significantly slower in the amblyopes compared to the control subjects for all three conditions. Mean reading speed in the amblyopes was 55% of that in the control subjects for amblyopic/nondominant eye viewing, 72% for nonamblyopic/dominant eye viewing, and 67% for binocular viewing. Fixation duration and the number of regressive saccades per line were the oculomotor parameters most associated with these changes in reading speed. No significant differences were apparent for the number of progressive saccades per line or the amplitude of progressive saccades.
In conclusion, this study showed impaired reading in both the amblyopic and non-amblyopic eye, and during binocular viewing, in amblyopic patients. These reading deficits are associated with saccadic and fixation patterns and may be the result of crowding and suppression scotomas experienced by amblyopes. This study suggests that there may be value in including reading charts, in addition to using high-contrast visual acuity charts, in the assessment of visual function in patients with strabismic amblyopia.
4. Hess RF, Thompson B. Amblyopia And The Binocular Approach To Its Therapy. Vision Res. 2015 Sep;114:4-16.
There is growing evidence that abnormal binocular interactions play a key role in amblyopia. In particular, stronger suppression of the amblyopic eye has been associated with poorer amblyopic eye visual acuity and a new therapy has been described that directly targets binocular function and has been found to improve both monocular and binocular vision in adults and children with amblyopia. Furthermore, non-invasive brain stimulation techniques that alter excitation and inhibition within the visual cortex have been shown to improve vision in the amblyopic eye. The aim of this review is to summarize this previous work and interpret the therapeutic effects of binocular therapy and non-invasive brain stimulation in the context of three potential neural mechanisms; active inhibition of signals from the amblyopic eye, attenuation of information from the amblyopic eye and metaplasticity of synaptic long term potentiation and long term depression.
5. Suttle Cm, Melmoth Dr, Finlay Al, Et Al.Eye Hand Coordination Skills In Children With And Without Amblyopia. Invest Ophthal Vis Sci. 2011;52:1851-64.
This study was designed to investigate whether binocular vision affects eye-hand coordination in children with and without amblyopia.
This study compared performances of non-amblyopic patients (36 children, ages of five and 11, and 11 adults, ages 20-42 years) to 21 children with strabismic or anisometropic amblyopia. Each participant was seated at a table, asked to reach out with his or her preferred hand and grasp an object by its middle, transplant the object on the table, and return his or her hand to starting position. Infrared markers, on the patients’ hands and objects, and cameras, captured aspects of the task, including reaction time, velocity, trajectory, grip adjustments, and overall execution time.
Patients were tested under binocular, non-dominant monocular, and dominant monocular viewing conditions.
The amblyopic patients’ performance was more poorly controlled under all viewing conditions than age-matched peers in the control group. These patients took longer to reach the object and made more frequent errors. The deficiencies in performance were more obvious when amblyopic patients with poor/absent stereopsis—not necessarily poor visual acuity—were tested under binocular conditions. In particular, amblyopic patients performed equally poorly when viewing monocularly with either eye, supporting the belief that the “good,” or dominant, eye of a patient with amblyopia is not the same as the dominant eye of a patient with normal vision.
Children in both groups showed normal developmental changes in visuomotor control. Young children (ages 5-8) show strong tendencies to use a “feed forward” system of processing—spending most time and energy on gathering information about the subject and environment before action, then making ballistic movements to execute the task. Children aged 7-8 years showed signs of transition, as they divided time between pre-action data collection and “online” or live-action feedback to make corrective movements when reaching. At this age, children began to incorporate visual feedback. Improvements in reach-grasp deficits may be accelerated with improvements in stereopsis.
6. The Pediatric Eye Disease Investigator Group (Pedig). Risk Of Amblyopia Recurrence After Cessation Of Treatment. Jaapos. 2004;8:420-8.
BACKGROUND: Although amblyopia can be successfully treated with patching or atropine, there have been few prospective studies of amblyopia recurrence once treatment is discontinued.
METHODS: We enrolled 156 children with successfully treated anisometropic or strabismic amblyopia (145 completed follow-up), who were younger than 8 years of age and who received continuous amblyopia treatment for the previous 3 months (prescribed at least 2 hours of daily patching or prescribed at least one drop of atropine per week) and who had improved at least 3 logMAR levels during the period of continuous treatment. Patients were followed off treatment for 52 weeks to assess recurrence of amblyopia, defined as a 2 or more logMAR level reduction of visual acuity from enrollment, confirmed by a second examination. Recurrence was also considered to have occurred if treatment was restarted because of a nonreplicated 2 or more logMAR level reduction of visual acuity.
RESULTS: Recurrence occurred in 35 (24%) of 145 cases (95% confidence interval 17% to 32%) and was similar in patients who stopped patching (25%) and in patients who stopped atropine (21%). In patients treated with moderately intense patching (6 to 8 hours per day), recurrence was more common (11 of 26; 42%) when treatment was not reduced prior to cessation than when treatment was reduced to 2 hours per day prior to cessation (3 of 22; 14%, odds ratio 4.4, 95% confidence interval 1.0 to 18.7).
CONCLUSIONS: Approximately one fourth of successfully treated amblyopic children experience a recurrence within the first year off treatment. For patients treated with 6 or more hours of daily patching, our data suggest that the risk of recurrence is greater when patching is stopped abruptly rather than when it is reduced to 2 hours per day prior to cessation. A randomized clinical trial of no weaning versus weaning in successfully-treated amblyopia is warranted to confirm these observational findings.
7. Hess RF, Thompson B, Baker DH. Binocular Vision In Amblyopia: Structure, Suppression And Plasticity. Ophthalmic Physiol Opt. 2014 Mar;34(2):146-62.
The amblyopic visual system was once considered to be structurally monocular. However, it now evident that the capacity for binocular vision is present in many observers with amblyopia. This has led to new techniques for quantifying suppression that have provided insights into the relationship between suppression and the monocular and binocular visual deficits experienced by amblyopes. Furthermore, new treatments are emerging that directly target suppressive interactions within the visual cortex and, on the basis of initial data, appear to improve both binocular and monocular visual function, even in adults with amblyopia. The aim of this review is to provide an overview of recent studies that have investigated the structure, measurement and treatment of binocular vision in observers with strabismic, anisometropic and mixed amblyopia.
READING
1. Atzmon D, Nemet P, Ishay A, Karni E. A Randomized Prospective Masked And Matched Comparative Study Of Orthoptic Treatment Versus Conventional Reading Tutoring Treatment For Reading Disabilities In 62 Children. Binocular Vision And Eye Muscle Surgery Quarterly 8 (2): 91-106, 1993.
Schools need better and economical methods of treating reading disabilities. Controversies remain whether orthoptics and/or “visual training” can remedy reading disabilities. Therefore, and to extend our prior studies, we undertook a comparative and controlled study. 120 children with reading disability were tested extensively, matched and randomly divided into three groups: orthoptic, conventional (reading tutoring) and no-treatment control. Unfortunately, participants in the control group were unable to adhere to no treatment and were deleted. Each of the 40 children in the first two groups had 40 sessions, 20 minutes daily. Orthoptic treatment was directed to markedly increase fusional convergence amplitudes for both near and distance to 60 The two treatments were also carefully matched in time and effort. Examination of subjects revealed that 100% had poor fusional convergence amplitudes by our standards and 60% had 20 or less: two-thirds had a normal near point of convergence of 5 cm or less; many had a subjective reading and asthenopic symptoms in the presence of fusional convergence amplitudes said to be normal by other authorities.
Sixty-two children in 31 matched pairs completed the course of treatment and testing. The results were: equal and statistically significant (P<.05) marked improvement in reading performance in both treatment groups on essentially all tests.
Orthoptic treatment, to increase convergence amplitudes to 60 is as effective as conventional in-school reading tutoring treatment of reading disabilities. An advantage of orthopic treatment was that subjective reading and asthenopic symptoms virtually disappeared after orthoptics. We recommend orthoptic treatment as: 1) an effective alternate primary treatment: 2) adjunctive treatment for those who do not respond well to standard treatment: and 3) as primary treatment in any case with asthenopic symptoms of/or convergence inadequacy.
2. Fischer, Hartnegg, Klaus. Effects Of Visual Training On Saccade Control In Dyslexia. Perception 29: 531-542, 2000.
This study reports the effects of daily practice of three visual tasks on the saccadic performance of the 85 dyslexic children in the age range of 8 to 15 years. The 9 children were selected from among other dyslexics because they showed déficits in their eye-movement control, especially in fixation stability and/or voluntary saccade control. The eye movements were measured in an overlap prosaccade and a gap antisaccade task before and after the training. The three tasks used for the training included a fixation, a saccade, and a distractor condition. In any of these tasks, the subject had to detect the last orientation of a small pattern which rapidly changed its orientation between up, down, right, and left, before it disappeared after some time. The task was to press one of four keys corresponding to the last orientation. The visual pattern was presented on and LCD display of a small handheld instrument given to the children for daily used at home. The results indicate that daily practice improved not only the perceptual capacity, but also the voluntary saccade control, within 3 to 8 weeks. After the training, the group of dyslexics was no longer statistically different from the control group.
3. Halliwell, J., Solan, H., The Effect Of A Supplemental Perceptual Training Program On Reading Achievement. Exceptional Children 38: 613-22, 1972.
At the beginning of the first grade, 105 students designated as potential Reading problems were divided into three groups of 35 children each: experimental I, which received supplementary perceptual training in addition to the regular reading program; experimental II, which received traditional supplementary reading instruction in addition to the regular reading program; and the control group, which received no supplementary instruction. The Metropolitan Achievement Test (MAT) was administered at the end of May. The statistical analysis of the data indicated that, of all the groups, only the experiment I total group and the experimental I boys read significantly better than the respective control groups on the reading subtest of the MAT.
4. Harris P. Learning-Related Visual Problems In Baltimore City: A Long-Term Program. Journal Of Optometric Vision Development 33 (2): 75-115, 2002.
A longitudinal, single-masked, random sample study of children at a Baltimore City Public Elementary school documents the prevalence of learning-related visual problems in the inner city of Baltimore and tests the effectiveness of visión therapy. Vision therapy was provided to one of the randomly selected groups and data were collected on optometric tests, visual performance tests, and standardized achievement tests before and after treatment was provided. Data presented show that the vision therapy program has made a significant difference in the demand level of reading that could be read for understanding, in math achievement on standardized testing, and in reading scores on standardized testing, as well as on infrared eye-movement Visagraph recordings, which show significant changes on nearly all mechanical aspects of the reading process.
5. Mckane F, Et Al. A Comparison Of Auditory/ Language Therapy With School Visual Support Procedures In A Public School Setting. Journal Of Optometric Vision Development 32 (2): 83-92, 2001.
Some hold that poor reading eye movements are caused by poor language skills and if the auditory/ language skills were improved that reading and eye movements during reading would also improve. Twenty-nine third grade children who had previously been identified as being below average in some academic area were the subjects of this study. The experimental group contained 18 subjects, equally distributed between genders. After screening evaluations, all children were enrolled in an auditory/language enrichment program and the experimental group also received school based vision techniques which were individually programmed and administered by school personnel, in the school setting daily for 30 minutes a day for 3.5 months. Both groups improved significantly over pre-test scores on the reading aspect of the WRAT and Reading rate with comprehension as measured by the –Visagraph. The experimental group also demonstrated a significant improvement in reading eye movements as measured by the Visagraph, but the control group did not. The authors concluded that both visual and auditory/language intervention has a positive effect on the reading WRAT scores as well as the reading rate with comprehension. Reading eye movements, however, were significantly improved only with visual intervention and not with auditory/language therapy.
6. Orfield A, Basa F, Yun J. Vision Problems Of Children In Poverty In An Urban School Clinic: Their Epidemic Numbers, Impact On Learning, And Approaches To Remediation. Journal Of Optometric Vision Development 32 (3): 114- 141, 2001.
The Mather School pilot study explores the relationship between vision and learning by analyzing clinical vision data gathered in an urban school eye clinic from fall 1993 to spring 1999, and relating the vision findings with available standardized test scores and teacher grades. There were 1544 vision evaluations on 801 students, 226 extended functional vision exams on students who failed the initial evaluation, 79 children who received some vision therapy and 116 who received glasses, mostly for close work, and another 85 who received prescription for glasses. Our in-school evaluations found a higher incidence of vision problems than reported in previous studied. Without counting the visual tracking test, 41% failed: adding the tracking test, 53% failed. The majority of the vision problems we found were related to near vision, including a great deal of hyperopia, and were associated with lower average test scores. Our treatments of reading glasses and vision therapy improved visual function on specific tests, with those who had the poorest findings on individual measures improving the most. Correlated with these treatments are improvements in teacher grades, percentiles, and grade equivalents on standardized tests in reading and mathematics. Even with our limited study, the data suggests that there is a high incidence of these problems, that some of these problems are correlated with lower scores in reading and math, that they can be treated in a school setting, that school screenings should be expanded to include more near point tests, that detailed functional vision exams should be required of all children falling behind in school, and that The Developmental Eye Movement test, which 24.5% of the children failed, is an excellent predictor of a significant percent of reading failure risk and should be administered to all school children in the early grades so that help can be given early. Remediation for poor visual skills is as important as remediation for learning failure, because lack of many of these skills correlate with learning problems.
7. Rounds BB, Manley CW, Norris RH. The Effect Of Oculomotor Training On Reading Efficiency. Journal Of American Optometric Association 62 (2): 92-99, 1991.
The purpose of this study was to record and measure, by means of a microcomputer, the reading eye movements and reading efficiency of a sample of “poor readers” from an adult, professional school population. A program of oculomotor skill enhancement training was given to 10 students who also failed the reading test, but received no such training. All subjects’ eye movements were monitored and recorded individually while reading, using a Visagraph eye-Movement Recording System. The subjects were split into and experimental group (Receiving training) and a control group (receiving no training). Following a 12-hour program of “in office” and “home” training, the group receiving oculomotor training showed trends toward improved reading eye movement efficiency (number of regressions, number of fixations and span of recognition), compared to that of the untrained group.
8. Seiderman A. Optometric Vision Therapy- Results Of A Demonstration Project With A Learning Disabled Population. Journal Of American Optometric Association 51(5): 489-492, 1980.
Thirty-six children attending a private school for learning disabled children were diagnosed as having visual and /or perceptual disorders. The experimental group received individual programming in visual and perceptual development at their appropriate developmental levels. The control group received instruction in physical education, art or music classes. Both groups received individualized reading assistance. Statistical analysis of the two year demonstration project, which included nine months of actual training, indicated that the experimental group made significant gains in reading as compared to the control group. The improvement in basic instructional level of The Informal Reading Inventory (Temple University), and the Word Reading and Paragraph Meaning subtests of the Stanford Achievement Tests, and the actual classroom reading levels were all statistically significant. The Informal Word Recognition Invention (Daniels) and the spelling subtest of the Stanford Achievement Tests showed a definite trend approaching statistical significance.
9. Sigler G, Wylie T. The Effect Of Vision Therapy On Reading Rate: A Pilot Study. Journal Of Behavioral Optometry 5 (4): 99-102, 1994.
Three subjects, two aged 8 and one age 10, with identified visual system disorders were selected as subjects to evaluate the effects of vision therapy on Reading efficiency as measured by reading rate. Reading rate measures were taken prior to initiation, at the conclusion, and 90 days post-visual therapy. The results were that all subjects had accelerated reading rate gains during the period of vision therapy and that the reading rates for two of the three subjects continued to increase in the post-therapy (maintenance) period. All three subjects experienced positive gains over the period (180 days) of the study.
10. Solan, H., Shelley-Tremblay, J., Et Al. Effect Of Attention Therapy On Reading Comprehension. Journal Of Learning Disabilities 36(6): 556-563, 2003.
This study quantified the influence of visual attention therapy on the Reading comprehension of Grade 6 children with moderate reading disabilities (RD) in the absence of specific reading remediation. Thirty students with below-average reading scores were identified using standardized reading comprehension tests.
Fifteen children were placed randomly in the experimental group and 15 in the control group. The Attention Battery of the Cognitive Assessment System was administered to all participants. The experimental group received 12 one-hour sessions of individually monitored, computer-based attention therapy programs; the control group received no therapy during their 12-week period. Each group was retested on attention and reading comprehension measures. In order to stimulate selective and sustained visual attention, the vision therapy stressed various aspects of arousal, activation, and vigilance. At the completion of attention therapy, the mean standard attention and reading comprehension scores of the experimental group had improved significantly. The control group, however, showed no significant improvement in reading comprehension scores after 12 weeks. Although uncertainties still exist, this investigation supports the notion that visual attention is malleable that the attention therapy has significant effect on reading comprehension in this often neglected population.
11. Solan H, Larson S, Shelley-Tremblay J, Ficarra A, Silverman M. Role Of Visual Attention In Cognitive Control Of Oculomotor Readiness In Students With Reading Disabilities. Journal Of Learning Disabilities 34 (2): 107-118, 2001.
This study investigated eye movement and comprehension therapy in Grade 6 children with reading disabilities (RD). Both order of therapy and type of therapy were examined. Furthermore, the implications of visual attention in ameliorating reading disability are discussed. Thirty-one students with RD were identified using standardized reading comprehension tests. Eye movements were analyzed objectively using an infared recording device. Reading scores of participating children were 0.5 to 1 SD below the national mean. Testing took place before the start of therapy (T1) and was repeated after 12 weeks (T2) and 24 weeks (T3) of therapy. One group of students had eye movement therapy first, followed by comprehension therapy; in the other group, the order was reversed. Data were evaluated using a repeated measures MANOVA and post hoc tests. At T1, mean reading grade was 2 years below grade level, and eye movement scores were at about Grade 2 level. Mean growth in reading comprehension for the total simple was 2.6 years at T3: equally significant improvement was measured in eye movements. Learning rate in reading comprehension improved from 60% (T1) to 400% (t3). Although within group differences were statistically significant at T2 and T3. Eye movement therapy improved eye movements and also resulted in significant gains in reading comprehension. Comprehension therapy likewise produced improvement both in eye movement efficiency and in Reading comprehension. The results support the notion of a cognitive link among visual attention, oculomotor readiness, and reading comprehension.
ACOMMODATION
1. Sterner B, Abrahamsson M, Sjöström A. Accommodative Facility Training With A Long Term Follow Up In A Sample Of School Aged Children Showing Accommodative Dysfunction. Documenta Ophthalmologica 99: 93-101, 1999.
The primary aim of this project was to study the effect of flip lens-training on the accommodative function in a group of children with accommodative dysfunction and subjective symptoms such as asthenopia, headache, blurred vision, and avoidance of near activity. We also wanted to measure the accommodative facility among the children in comparison with a control group. Another aim of the study was whether flip lens-training increased accommodative facility, and to find out if it also had a positive effect on their asthenopia and related problems also in long term. Following the training period the accommodative facility and accommodative function significantly increased and two years after finishing the training period no child had regained any subjective symptoms and the objective findings were almost the same as at the end of facility training period. These results suggest that accommodative facility training is an efficient method built on loss of symptoms among children with accommodative infacility.
2. Scheiman M, Cotter S, et al . Treatment of Accommodative Dysfunction in Children: Results from an Random Clinical Trial. Optom Vis Sci. 2011 Nov; 88(11): 1343–1352.
PURPOSE To report the effectiveness of various forms of vision therapy/orthoptics in improving accommodative amplitude and facility in children with symptomatic convergence insufficiency (CI) and co-existing accommodative dysfunction.
METHODS In a randomized clinical trial, 221 children 9 to 17 years with symptomatic CI were assigned to one of four treatments. Of the enrolled children, 164 (74%) had accommodative dysfunction; 63 (29%) had a decreased amplitude of accommodation with respect to age, 43 (19%) had decreased accommodative facility, and 58 (26%) had both. Analysis of variance models were used to compare mean accommodative amplitude and accommodative facility for each treatment group after 4, 8, and 12 weeks of treatment.
RESULTS After 12 weeks of treatment, the increases in amplitude of accommodation [office-based vergence/accommodative therapy with home reinforcement group (OBVAT) 9.9D, home-based computer vergence/accommodative therapy group (HBCVAT+) 6.7D, home-based pencil push-up therapy group (HBPP) 5.8D] were significantly greater than in the office-based placebo therapy group (2.2D) (p-values ≤ 0.010). Significant increases in accommodative facility were found in all groups (OBVAT: 9cpm, HBCVAT+: 7cpm, HBPP: 5cpm, OBPT: 5.5cpm); only the improvement in the OBVAT group was significantly greater than that found in the OBPT group (p = 0.016). One year after completion of therapy, reoccurrence of decreased accommodative amplitude was present in only 12.5% and accommodative facility in only 11%.
CONCLUSIONS Vision therapy/orthoptics is effective in improving accommodative amplitude and accommodative facility in school-age children with symptomatic CI and accommodative dysfunction.
PERFORMANCE IN POPULATION OF INFANT EDUCATION AGE GROUP
1. Streff JW, Poynter HL, Jinks B, Wolff B. Changes In Achievement Scores As A Result Of A Joint Optometry And Education Intervention Program. Journal Of The American Optometric Association 61 (6): 475-81, 1990.
This study tested the effect of a visually directed intervention program on changes in standardized test results of intelligence quotient and achievement during kindergarten. Two groups of 19 kindergarten children from equivalent schools were matched for intelligence quotient, age, and sex. Fall and Spring measurements were made in the following areas: intelligence quotient, academic achievement tests, and paper and pencil perceptual tests. A visually based intervention program involving both optometry and education was provided for the experimental group. Kindergarten children in the experimental group who received the visually directed optometry and education intervention program showed significant differences in the rate of change in four of the eight tested areas when matched to the control group.
AMBLYOPIA
1. Hess R, Mansouri B, Thompson B.A Binocular Approach To Treating Amblyopia: Antisuppression Therapy. Opt Vis Sci 2010;87:697-704
The most common form of treatment for amblyopia is to patch the good eye to improve the function of the amblyopic eye. This study proposes a new way to treat amblyopic patients utilizing a binocular method to treat amblyopia. The theory behind the study is that recent research has shown that amblyopes have intact, but suppressed, binocular systems.
These researchers developed a novel approach of quantifying and treating the amblyopic suppression. Using random dot kinematograms and a coherence motion discrimination task, they found that they can determine how much binocularity a patient has. The subject would look at a “signal” consisting of dots that move in the same direction in 1 eye while looking at “noise” consisting of random movement in the other eye. The “noise” in one makes it harder to see the “signal” in the other. In a normal binocular patient, it does not matter which eye sees the signal and which sees noise. However, in amblyopes there is an imbalance; if the fixating eye sees the signal and the amblyopic eye sees noise, performance is at a ceiling. If the fixating eye sees the noise and the amblyopic eye sees the signal, performance is at chance. However, a balance can be found showing that eyes can work binocularly.
In this case report 3 patients underwent the treatment procedure. All patients had decreased best corrected visual acuity (BCVA) in the amblyopic eye from 20/63 to 20/400, intermittent fusion or no fusion on Worth 4 Dot, and no Randot. Two had strabismic amblyopia and one had anisometropic amblyopia. All three showed improvements in BCVA and Randot stereopsis at the end of treatment.
The researchers also note an improvement in 8/10 adult amblyopes treated to date and suggests a new method of treatment for amblyopes.
2. Pediatric Eye Disease Investigator Group Writing Committee. A Randomized Trial Comparing Bangerter Filters And Patching For The Treatment Of Moderate Amblyopia In Children. Ophthalmology 2010; 117:998-1004
The purpose of this study was to determine whether visual acuity improvement with Bangerter filters is similar to improvement with patching as initial therapy for children with moderate amblyopia. To determine this, the investigators incorporated a randomized clinical trial with 186 children, from ages 3 to <10 years, with moderate amblyopia (20/40-20/80).
The authors noted that potential advantages of using Bangerter filters versus patching include: the ability to change the density of the filter to alter levels of deprivation, the possibility of better compliance due to the filter being placed on the patients actual glasses, the possibility of less disruption of binocular vision, and better acceptance because the filter is not readily apparent to casual observers.
To participate in the study, participants had to meet the following criteria: age 3 to <10 years, visual acuity of 20/40 to 20/80 in the amblyopic eye, visual acuity of 20/40 or better in the fellow eye, and an interocular acuity difference >3 lines. The participants must also be currently wearing glasses and have the presence or history of an amblyogenic factor meeting study-specified criteria for strabismus and/or anisometropia.
Patients were seen for follow-up visits at 6, 12, 18, and 24 weeks. 81 of 89 (91%) Bangerter participants and 88 of 97 (91%) patching participants completed their 24 week primary outcome examination. Visual acuity in the Bangerter group was improved from baseline by an average of 1.9 lines, while the patching group improved by 2.3 lines. The rate of amblyopic eye improvement, time to 20/25 or better amblyopic eye acuity, and improvement of visual acuity by 3 or more lines were not statistically different between treatment groups. Therefore, the authors could not conclude that either patching or Bangerter treatment is superior to the other. Parent reported negative impact of treatment with respect to adverse effects, compliance, and social stigma was lower with the Bangerter filters than with patching based on the Parental Amblyopia Treatment Index completed by parents.
Bangerter foils remain an option for treating amblyopia in children.
3. Mansouri B1, Singh P, Globa A, Pearson P. Binocular Training Reduces Amblyopic Visual Acuity Impairment. Strabismus. 2014 Mar;22(1):1-6.
Amblyopia is the most common cause of monocular visual impairment. Patching, which is modestly effective, is the current treatment of amblyopia in children. There is no clinically approved treatment for adults. The present study is a clinical trial (non-sham controlled and non-randomized) that assessed the efficacy of binocular training for improvement of the visual acuity in children and adults with amblyopia. Twenty-two amblyopic subjects ranging in age from 5 to 73 (mean: 36.2) years for whom patching and/or surgical treatments did not correct their visual impairment completed an average of 14.5 sessions of binocular training over a period of 4 to 6 weeks. Random dot kinematograms were presented dichoptically to the two eyes and the participants’ task was to identify the direction of motion of the targets. Mean visual acuity improvement was 0.34 LogMAR (range: 0.1-0.58 LogMAR) and was shown to persist 6 months following the cessation of binocular training. Our study provides results in a large number of patients that confirm the clinical effectiveness of binocular training as a treatment for amblyopia in improving visual acuity in both children and adults. Moreover, this study is the first to demonstrate that the improvements in visual function were maintained for 6 months in the absence of any additional treatment.
4. Yalcin E, Balci O. Efficacy Of Perceptual Vision Therapy In Enhancing Visual Acuity And Contrast Sensitivity Function In Adult Hypermetropic Anisometropic Amblyopia. Clin Ophthalmol. 2014;8:49-53
BACKGROUND: The purpose of this study was to evaluate the efficacy of neural vision therapy, also termed perceptual vision therapy, in enhancing best corrected visual acuity (BCVA) and contrast sensitivity function in amblyopic patients.
METHODS: This prospective study enrolled 99 subjects previously diagnosed with unilateral hypermetropic amblyopia aged 9-50 years. The subjects were divided into two groups, with 53 subjects (53 eyes) in the perceptual vision therapy group and 46 subjects (46 eyes) in the control group. Because the nature of the treatment demands hard work and strict compliance, we enrolled the minimal number of subjects required to achieve statistically significant results. Informed consent was obtained from all subjects. Study phases included a baseline screening, a series of 45 training sessions with perceptual vision therapy, and an end-of-treatment examination. BCVA and contrast sensitivity function at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies were obtained for statistical analysis in both groups. All subjects had follow-up examinations within 4-8 months. With the exception of one subject from the study group and two subjects from the control group, all subjects had occlusion during childhood. The study was not masked.
RESULTS: The results for the study group demonstrated a mean improvement of 2.6 logarithm of the minimum angle of resolution (logMAR) lines in visual acuity (from 0.42 to 0.16 logMAR). Contrast sensitivity function improved at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies. The control group did not show any significant change in visual acuity or contrast sensitivity function. None of the treated eyes showed a drop in visual acuity. Manifest refractions remained unchanged during the study.
CONCLUSION: The results of our study demonstrate the efficacy of perceptual vision therapy in improving visual acuity. The 2.6 logMAR lines improvement in visual acuity is encouraging, and is consistent with the results of previous studies. However, long-term follow-up and further studies are needed.
5. Hess RF, Mansouri B, Thompson B.Restoration Of Binocular Vision In Amblyopia. Strabismus. 2011 Sep;19(3):110-8
PURPOSE: To develop a treatment for amblyopia based on re-establishing binocular vision.
METHODS: A novel procedure is outlined for measuring and reducing the extent to which the fixing eye suppresses the fellow amblyopic eye in adults with amblyopia. We hypothesize that suppression renders a structurally binocular system, functionally monocular.
RESULTS: We demonstrate that strabismic amblyopes can combine information normally between their eyes under viewing conditions where suppression is reduced by presenting stimuli of different contrast to each eye. Furthermore we show that prolonged periods of binocular combination leads to a strengthening of binocular vision in strabismic amblyopes and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Additionally, stereoscopic function was established in the majority of patients tested. We have implemented this approach on a headmounted device as well as on a handheld iPod.
CONCLUSION: This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.
6. Li RW, Young KG, Hoenig P, Levi DM.Perceptual Learning Improves Visual Performance In Juvenile Amblyopia. Invest Ophthalmol Vis Sci. 2005 Sep;46(9):3161-8.
PURPOSE: To determine whether practicing a position-discrimination task improves visual performance in children with amblyopia and to determine the mechanism(s) of improvement.
METHODS: Five children (age range, 7-10 years) with amblyopia practiced a positional acuity task in which they had to judge which of three pairs of lines was misaligned. Positional noise was produced by distributing the individual patches of each line segment according to a Gaussian probability function. Observers were trained at three noise levels (including 0), with each observer performing between 3000 and 4000 responses in 7 to 10 sessions. Trial-by-trial feedback was provided.
RESULTS: Four of the five observers showed significant improvement in positional acuity. In those four observers, on average, positional acuity with no noise improved by approximately 32% and with high noise by approximately 26%. A position-averaging model was used to parse the improvement into an increase in efficiency or a decrease in equivalent input noise. Two observers showed increased efficiency (51% and 117% improvements) with no significant change in equivalent input noise across sessions. The other two observers showed both a decrease in equivalent input noise (18% and 29%) and an increase in efficiency (17% and 71%). All five observers showed substantial improvement in Snellen acuity (approximately 26%) after practice.
CONCLUSIONS: Perceptual learning can improve visual performance in amblyopic children. The improvement can be parsed into two important factors: decreased equivalent input noise and increased efficiency. Perceptual learning techniques may add an effective new method to the armamentarium of amblyopia treatments.
7. FitzGerald DE, Krumholtz I. Maintenance of improvement gains in refractive amblyopia: a comparison of treatment modalities. Optometry. 2002 Mar;73(3):153-9.
BACKGROUND: In June of 1999, an initial study reported on the effect of differing treatment modalities in improving visual acuity and stereoacuity in patients with unilateral refractive amblyopia. This study reports on the patients’ visual maintenance of acuity gains for each specified treatment modality. Patients were re-evaluated over a 1- to 2-year period after cessation of treatment.
METHODS: Records of patients who participated in the initial study were retrospectively reviewed 1 to 2 years after cessation of therapy to determine whether visual acuity gains were maintained.
RESULTS: Patients were divided according to treatment modalities. Results for the three patient groups were as follows: 50% of patients with optical correction alone maintained visual acuity improvement; 60% of patients with optical correction and occlusion maintained visual acuity gains; and 100% of patients with optical correction, occlusion, and vision therapy had maintained visual acuity gains. Of the three age groups–4 years to 6 years, 11 months; 7 years to 9 years, 11 months; and 10 to 14 years–the oldest age group maintained the highest percentage of visual acuity gains.
CONCLUSIONS: In our sample, at least 50% of the unilateral anisometropic amblyopic patients, who initially experienced visual acuity gains after treatment (regardless of treatment modality or age) maintained those acuity gains at 1- to 2-year followup. One hundred percent of those patients who received the vision therapy modality of treatment retained the improvement at followup-a statistically significant difference when compared with the other two groups.
BRAIN INJURY
1. Ciuffreda Kj, Kapoor N. Oculomotor Dysfunctions, Their Remediation, And Reading-Related Problems In Mild Traumatic Brain Injury. Journal of Behavioral Optometry 2007; 18:72-77.
In patients with mild traumatic brain injury (TBI), symptoms of oculomotor-based reading problems are common. This review examines the most common reading-related problems patients with mild TBI, and the effects of simple oculomotor training on these symptoms.
The first retrospective study examined the most common categories of oculomotor dysfunction and their frequency amongst 160 patients with TBI. Vergence, saccade, and accommodative dysfunctions had the highest frequency of occurrence. 90% of patients in this TBI sample manifested a deficit in one or more of the following: vergence (56.3%), version (51.3%), accommodation (41.1%), strabismus (25.6%), and cranial nerve palsy (6.9%).
The second retrospective study showed the treatment success of conventional optometric vision therapy for 33 patients with mild TBI. These patients received between 10 and 30 in-office vision therapy sessions coupled with 10-40 hours of home training. The most common symptom related to near work was oculomotor difficulty when reading (~80%), and the most common signs were receded near point of convergence and abnormal saccadic tracking (~70%). 90% of patients in this study showed improvement or normalization of at least one symptom and one sign following treatment.
The third study aimed to show whether simple versional oculomotor techniques could improve reading ability, both objectively and subjectively, for patients with mild TBI. In this small group (n=9), every patient had symptoms and signs of poor reading ability. Reading rate and eye movements were assessed objectively using the Visagraph.
Training consisted of two 36 minute sessions a week, for eight weeks using computer-controlled stimuli; including fixation, saccade, pursuit, and simulated reading protocols. Following oculomotor training, each individual could read for a longer time and with greater comfort. Reading rates increased 10-33% in five patients. All improvements were maintained at the three-month follow-up.
These three studies show the frequency of oculomotor dysfunction, the symptoms experienced while reading, and the improvements following vision therapy both subjectively and objectively, for patients with mild TBI. The combinations of these studies, along with brain imaging techniques to show neural changes produced by optometric vision therapy, will be used to design an oculomotor training protocol for individuals with mild TBI.
2. Ciuffreda KJ, Rutner D, Kapoor N, Suchoff IB, Craig S, Han ME. Vision Therapy For Oculomotor Dysfunctions In Acquired Brain Injury: A Retrospective Analysis. Optometry. 2008 Jan; 79(1):18-22.
BACKGROUND: Oculomotor dysfunctions are among the most common abnormalities found in the brain-injured population. The purpose of the current study was to determine retrospectively the effectiveness of conventional optometric vision therapy for oculomotor disorders of vergence and version in a sample of ambulatory, visually symptomatic, predominantly adult outpatients who had either mild traumatic brain injury (TBI) or cerebrovascular accident (CVA).
METHODS: A computer-based query for acquired brain injury patients examined between the years of 2000 and 2003 was conducted in our clinic. This yielded 160 individuals with mild TBI and 60 with CVA. Of these patients, only those for whom vision therapy was prescribed and who completed an optometric vision therapy program for remediation of their oculomotor dysfunctions were selected. This included 33 with TBI and 7 with CVA. The criterion for treatment success was denoted by marked/total improvement in at least 1 primary symptom and at least 1 primary sign.
RESULTS: Ninety percent of those with TBI and 100% of those with CVA were deemed to have treatment success. These improvements remained stable at retesting 2 to 3 months later.
CONCLUSION: Nearly all patients in the current clinic sample exhibited either complete or marked reduction in their oculomotor-based symptoms and improvement in related clinical signs, with maintenance of the symptom reduction and sign improvements at the 2- to 3-month follow-up. These findings show the efficacy of optometric vision therapy for a range of oculomotor abnormalities in the primarily adult, mild brain-injured population. Furthermore, it shows considerable residual neural plasticity despite the presence of documented brain injury.
3. Thiagarajan P, Ciuffreda KJ.Effect Of Oculomotor Rehabilitation On Accommodative Responsivity In Mild Traumatic Brain Injury. J Rehabil Res Dev. 2014;51(2):175-91
Accommodative dysfunction is a common oculomotor sequelae of mild traumatic brain injury (mTBI). This study evaluated a range of dynamic (objective) and static (subjective) measures of accommodation in 12 nonstrabismic individuals with mTBI and near vision-related symptoms before and after oculomotor training (OMT) and placebo (P) training (6 wk, two sessions per week, 3 h of training each). Following OMT, the dynamics of accommodation improved markedly. Clinically, there was a significant increase in the maximum accommodative amplitude both monocularly and binocularly. In addition, the near vision symptoms reduced along with improved visual attention. None of the measures were found to change significantly following P training. These results provide evidence for a significant positive effect of the accommodatively based OMT on accommodative responsivity. Such improvement is suggestive of oculomotor learning, demonstrating considerable residual brain-visual system plasticity in the adult compromised brain.
CONVERGENCE INSUFFICIENCY
1. Scheiman, M, Kulp, M, Cotter, S, Et. Al. Vision Therapy/ Orthoptics For Symptomatic Convergence Insufficiency In Children: Treatment Kinetics. Optom Vis Sci. 2010; 87: 593-603.
PURPOSE: To evaluate the kinetics of change in symptoms and signs of convergence insufficiency (CI) during 12 weeks of treatment with commonly prescribed vision therapy/orthoptic treatment regimens.
METHODS: In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic CI were assigned to home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), or office-based placebo therapy with home reinforcement (OBPT). Symptoms and signs were measured after 4, 8, and 12 weeks of treatment. The outcome measures were the mean CI Symptom Survey (CISS), near point of convergence (NPC), positive fusional vergence (PFV), and proportions of patients who were classified as successful or improved based on a composite measure of CISS, NPC, and PFV.
RESULTS: Only the OBVAT group showed significant improvements in symptoms between each visit (p < 0.001). Between weeks 8 and 12, all groups showed a significant improvement in symptoms. Between-group differences were apparent by week 8 (p = 0.037) with the fewest symptoms in the OBVAT group. For each group, the greatest improvements in NPC and PFV were achieved during the first 4 weeks. Differences between groups became apparent by week 4 (p < 0.001), with the greatest improvements in NPC and PFV in the OBVAT group. Only the OBVAT group continued to show significant improvements in PFV at weeks 8 and 12. The percentage of patients classified as “successful” or “improved” based on our composite measure increased in all groups at each visit.
CONCLUSIONS: The rate of improvement is more rapid for clinical signs (NPC and PFV) than for symptoms in children undergoing treatment for CI. OBVAT results in a more rapid improvement in symptoms, NPC and PFV, and a greater percentage of patients reaching pre-determined criteria of success when compared with HBPP, HBCVAT+, or OBPT.
2. Alvarez Tl, Vicci Vr, Alkan Y, Kim Eh, Et Al. Vision Therapy In Adults With Convergence Insufficiency: Clinical And Functional Magnetic Resonance Imaging Measures. Optom Vis Sci. 2010; 87: E985-E1102.
This pilot study aimed to provide data about vergence system changes in patients undergoing vision therapy for convergence insufficiency (CI), by measuring neural changes with functional magnetic resonance imaging (fMRI) scans. The study included four CI patients undergoing vision therapy, consisting of 18 hours of in-office and at-home therapy. There were 13 controls who did not receive therapy.
The fMRI scans were taken before and after vision therapy by measuring the activation extent of five different regions of interest (ROIs) of the brain: dorsolateral prefrontal cortex, frontal lobe, parietal lobe, cerebellum, and the brain stem. The researchers found there was an increase in extent of activation of several of the ROIs (frontal lobes, cerebellum and brainstem) after vision therapy compared to before vision therapy.
Five different static clinical parameters, stereopsis, NPC break value, recovery point of convergence (RPC), near fusional vergence amplitude, and dissociated near phoria, were measured before, midway, after, and 1 year post-vision therapy. These parameters positively correlated with the changes in cortical activity seen on fMRI. After vision therapy, the static parameters (except for stereopsis) and vergence dynamics significantly improved.
These results support that increased functional activity on fMRI after vision therapy may represent a correlation between clinical and physiological modifications of the visual system.
3. Randomized Clinical Trial Of Treatments For Symptomatic Convergence Insufficiency In Children. Arch Ophthalmol 2008:126:1336-49
The purpose of this study was to compare the efficacy of different therapeutic treatments for convergence insufficiency (CI) in children. In this randomized clinical trial, 221 children aged 9 to 17 with symptomatic CI were assigned to one of four 12 week treatments. Therapies compared included home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), and office-based placebo therapy with home reinforcement (OBPT).
Outcomes were measured using a standardized 15 question symptom survey, the convergence insufficiency symptom survey (CISS), administered before and after 12 weeks of a randomly-assigned therapy. Secondarily, outcomes were measured by comparing pre and post-therapy near point of convergence (NPC) and positive fusional vergence (PFV) values.
After 12 weeks of treatment, the OBVAT group demonstrated the most improvement in both the CISS and in NPC/positive fusional vergence measurements. A successful or improved outcome based on pre-determined success criteria was found in 73% of the OBVAT group, 43% of the HBPP, 33% of the HBCVAT+, and 35% of the OBPT groups, respectively.
The results of this study are directly applicable to clinical practice in the treatment of convergence insufficiency. Results clearly indicate that a 12 week regimen of OBVAT with home reinforcement is more effective in improving signs and symptoms associated with CI than a 12 week program of HBPP or HBCVAT+.
4. Borsting E, Mitchell GL et al., Improvement in academic behaviors after successful treatment of convergence insufficiency. Optom Vis Sci. 2012 Jan;89(1):12-8
PURPOSE: To determine whether treatment of symptomatic convergence insufficiency (CI) has an effect on Academic Behavior Survey (ABS) scores.
METHODS: The ABS is a six-item survey developed by the Convergence Insufficiency Treatment Trial Group that quantifies the frequency of adverse school behaviors and parental concern about school performance on an ordinal scale from 0 (never) to 4 (always) with total scores ranging from 0 to 24. The ABS was administered at baseline and after 12 weeks of treatment to the parents of 218 children aged 9 to 17 years with symptomatic CI, who were enrolled in the Convergence Insufficiency Treatment Trial and randomized into (1) home-based pencil push-ups; (2) home-based computer vergence/accommodative therapy and pencil push-ups; (3) office-based vergence/accommodative therapy with home reinforcement; and (4) office-based placebo therapy with home reinforcement. Participants were classified as successful (n = 42), improved (n = 60), or non-responder (n = 116) at the completion of 12 weeks of treatment using a composite measure of the symptom score, nearpoint of convergence, and positive fusional vergence. Analysis of covariance methods were used to compare the mean change in ABS between response to treatment groups while controlling for the ABS score at baseline.
RESULTS: The mean ABS score for the entire group at baseline was 12.85 (SD = 6.3). The mean ABS score decreased (improved) in those categorized as successful, improved, and non-responder by 4.0, 2.9, and 1.3 points, respectively. The improvement in the ABS score was significantly related to treatment outcome (p < 0.0001), with the ABS score being significantly lower (better) for children who were successful or improved after treatment as compared to children who were non-responders (p = 0.002 and 0.043, respectively).
CONCLUSIONS: A successful or improved outcome after CI treatment was associated with a reduction in the frequency of adverse academic behaviors and parental concern associated with reading and school work as reported by parents.
BINOCULAR PROBLEMS
1. Hussaindeen JR, Shah P, Ramani KK, Ramanujan L .Efficacy of vision therapy in children with learning disability and associated binocular vision anomalies. J Optom. 2018 Jan-Mar; 11(1): 40–48.
Purpose: To report the frequency of binocular vision (BV) anomalies in children with specific learning disorders (SLD) and to assess the efficacy of vision therapy (VT) in children with a non-strabismic binocular vision anomaly (NSBVA).
Methods: The study was carried out at a centre for learning disability (LD). Comprehensive eye examination and binocular vision assessment was carried out for 94 children (mean (SD) age: 15 (2.2) years) diagnosed with specific learning disorder. BV assessment was done for children with best corrected visual acuity of ≥6/9 – N6, cooperative for examination and free from any ocular pathology. For children with a diagnosis of NSBVA (n = 46), 24 children were randomized to VT and no intervention was provided to the other 22 children who served as experimental controls. At the end of 10 sessions of vision therapy, BV assessment was performed for both the intervention and non-intervention groups.
Results: Binocular vision anomalies were found in 59 children (62.8%) among which 22% (n = 13) had strabismic binocular vision anomalies (SBVA) and 78% (n = 46) had a NSBVA. Accommodative infacility (AIF) was the commonest of the NSBVA and found in 67%, followed by convergence insufficiency (CI) in 25%. Post-vision therapy, the intervention group showed significant improvement in all the BV parameters (Wilcoxon signed rank test, p < 0.05) except negative fusional vergence.
Conclusion: Children with specific learning disorders have a high frequency of binocular vision disorders and vision therapy plays a significant role in improving the BV parameters. Children with SLD should be screened for BV anomalies as it could potentially be an added hindrance to the reading difficulty in this special population.
PRESCRIPTION
1. Berntsen Da, Mutti Do, Zadnik K. The Effect Of Bifocal Add On Accommodative Lag In Myopic Children With High Accommodative Lag. Invest Ophthal Vis Sci 2010; 51(12):6104-6110.
Bifocal adds and progressive addition lenses (PALs) have been found to decrease accommodative lag and reduce hyperopic blur during near work, possibly delaying myopia progression. This study investigates how a bifocal add influences accommodative lag in children with myopia and a high accommodative lag.
Subjects included eighty-three (83) children between 6 to 11 years of age who fit the following criteria: myopia ranging from -0.75 diopter (D) to -4.50 D in either eye, accommodative lag of at least 1.30 D when presented with a 4 D stimulus, and near esophoria if the cycloplegic spherical equivalent refractive error was greater than -2.25 D. The children received either single vision spectacles or PALs with a +2.00 D add. The accommodative lag to a 4 D Badal stimulus was measured with both the child’s habitual correction and manifest correction in place.
Results of this study showed that a +2.00 D bifocal add does not eliminate a lag of accommodation, but can reduce accommodative lag by about 25% of the bifocal power. These results indicate that children with a higher accommodative lag had a greater reduction in the lag with a bifocal. There was a floor effect for every 1 (D) of lag (i.e. the +2.00 Add had no effect) but approximately a 50% reduction in lag for every diopter of lag great than 1. The authors recommend that future studies obtain data through both habitual and manifest correction in order to gain an appropriate measure of a myopic child’s accommodative lag.
2. Al-Bagdady M, Stewart Re, Watts P, Et Al. Bifocals And Down’s Syndrome: Correction Or Treatment? Ophthalmic And Physiol Optics 2009; 29: 416-21
This study looked at the effectiveness of bifocals in improving accommodation in children with Down’s Syndrome, since approximately 75% of these children have reduced accommodation. The author reviewed the clinical records of 40 children with Down’s Syndrome (ages 4.96-14.64) who were prescribed bifocals, and the effects these bifocals had on their accommodation at three different distances (10, 16.7, and 25 cm). Changes in accommodation with bifocals or after bifocals were discontinued was also assessed.
With bifocal treatment, 95% of the children achieved accurate accommodation when looking through their bifocal segment. When looking through the distance portion, 65% of the children had improvement in accommodation. Thirty five percent (35%) of the total study participants were able to discontinue bifocal lenses. All of the children who discontinued bifocals were reassessed at a later date, and all maintained accurate accommodation. Age, gender, visual acuity, presence of strabismus, and refractive error did not affect these results. Bifocals as a treatment for reduced accommodation in children with Down’s Syndrome can be considered a temporary treatment in at least one-third of children.