Visual therapy results for convergence insufficiency: a literature review

Interventions for convergence insufficiency: a network meta-analysis

BACKGROUND

Convergence insufficiency is a common binocular vision disorder in which the eyes have a strong tendency to drift outward (exophoria) with difficulty turning the eyes inward when reading or doing close work.

OBJECTIVES

To assess the comparative effectiveness and relative ranking of non-surgical interventions for convergence insufficiency through a systematic review and network meta-analysis (NMA).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PubMed and three trials registers up to 20 September 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) examining any form of non-surgical intervention versus placebo, no treatment, sham treatment, or other non-surgical interventions. Participants were children and adults with symptomatic convergence insufficiency.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. We performed NMAs separately for children and adults.

MAIN RESULTS

We included 12 trials (six in children and six in adults) with a total of 1289 participants. Trials evaluated seven interventions: 1) office-based vergence/accommodative therapy with home reinforcement; 2) home-based pencil/target push-ups; 3) home-based computer vergence/accommodative therapy; 4) office-based vergence/accommodative therapy alone; 5) placebo vergence/accommodative therapy or other placebo intervention; 6) prism reading glasses; and 7) placebo reading glasses. Six RCTs in the pediatric population randomized 968 participants. Of these, the Convergence Insufficiency Treatment Trial (CITT) Investigator Group completed four RCTs with 737 participants. All four CITT RCTs were rated at low risk of bias. Diagnostic criteria and outcome measures were identical or similar among these trials. The four CITT RCTs contributed data to the pediatric NMA, incorporating interventions 1, 2, 3 and 5. When treatment success was defined by a composite outcome requiring both clinical measures of convergence to be normal, and also show a pre-specified magnitude of improvement, we found high-certainty evidence that office-based vergence/accommodative therapy with home reinforcement increases the chance of a successful outcome, compared with home-based computer vergence/accommodative therapy (risk ratio (RR) 1.96, 95% confidence interval (CI) 1.32 to 2.94), home-based pencil/target push-ups (RR 2.86, 95% CI 1.82 to 4.35); and placebo (RR 3.04, 95% CI 2.32 to 3.98). However, there may be no evidence of any treatment difference between home-based computer vergence/accommodative therapy and home-based pencil/target push-ups (RR 1.44, 95% CI 0.93 to 2.24; low-certainty evidence), or between either of the two home-based therapies and placebo therapy, for the outcome of treatment success. When treatment success was defined as the composite convergence and symptom success outcome, we found moderate-certainty evidence that participants who received office-based vergence/accommodative therapy with home reinforcement were 5.12 (95% CI 2.01 to 13.07) times more likely to achieve treatment success than those who received placebo therapy. We found low-certainty evidence that participants who received office-based vergence/accommodative therapy with home reinforcement might be 4.41 (95% CI 1.26 to 15.38) times more likely to achieve treatment success than those who received home-based pencil push-ups, and 4.65 (95% CI 1.23 to 17.54) times more likely than those who received home-based computer vergence/accommodative therapy. There was no evidence of any treatment difference between home-based pencil push-ups and home-based computer vergence/accommodative therapy, or between either of the two home-based therapies and placebo therapy. One RCT evaluated the effectiveness of base-in prism reading glasses in children. When base-in prism reading glasses were compared with placebo reading glasses, investigators found no evidence of a difference in the three outcome measures of near point convergence (NPC), positive fusional vergence (PFV), or symptom scores measured by the Convergence Insufficiency Symptom Survey (CISS). Six RCTs in the adult population randomized 321 participants. We rated only one RCT at low risk of bias. Because not all studies of adults included composite success data, we could not conduct NMAs for treatment success. We thus were limited to comparing the mean difference (MD) between interventions for improving NPC, PFV, and CISS scores individually using data from three RCTs (107 participants; interventions 1, 2, 4 and 5). Compared with placebo treatment, office-based vergence accommodative therapy was relatively more effective in improving PFV (MD 16.73, 95% CI 6.96 to 26.60), but there was no evidence of a difference for NPC or the CISS score. There was no evidence of difference for any other comparisons for any outcomes. One trial evaluated base-in prism glasses prescribed for near-work activities and found that the prism glasses group had fewer symptoms compared with the placebo glasses group at three months (MD -8.9, 95% CI -11.6 to -6.3). The trial found no evidence of a difference with this intervention in NPC or PFV. No adverse effects related to study treatments were reported for any of the included studies. Excellent adherence was reported for office-based vergence/accommodative therapy (96.6% or higher) in two trials. Reported adherence with home-based therapy was less consistent, with one study reporting decreasing adherence over time (weeks 7 to 12) and lower completion rates with home-based pencil/target push-ups.

AUTHORS' CONCLUSIONS

Current research suggests that office-based vergence/accommodative therapy with home reinforcement is more effective than home-based pencil/target push-ups or home-based computer vergence/accommodative therapy for children. In adults, evidence of the effectiveness of various non-surgical interventions is less clear.

Comparison of Three Vision Therapy Approaches for Convergence Insufficiency

Purpose:

We compared the effectiveness of three active vision therapy approaches for convergence insufficiency (CI).

Methods:

This randomized clinical trial included patients meeting the eligibility criteria and with symptomatic CI, who were allocated into three groups. In the home-based vision orthoptic therapy (HBVOT) group, patients performed the pencil push-up procedure 15 min/day for 5 days/week. In the office-based vision orthoptic therapy (OBVOT) group, patients underwent 60-min orthoptic therapy using a major amblyoscope twice weekly with additional home orthoptic therapy. In the augmented office-based vision orthoptic therapy (AOBVOT) group, patients performed orthoptic exercises using 3-diopter over-minus lenses and a base-out prism in addition to major amblyoscope therapy, and additional home reinforcement was prescribed during the same time period.

Results:

All 84 subjects (mean age, 26.8 ± 8.3 years) showed a statistically significant improvement in near exophoria, positive fusional vergence (PFV) at near, near point of convergence (NPC), stereoacuity, and Convergence Insufficiency Symptom Survey (CISS) scores at follow-up. Exophoria decreased by 64%, 68%, and 85% in the HBVOT, OBVOT, and AOBVOT groups, respectively (P = 0.2). PFV increased by 68%, 100%, and 100% in the HBVOT, OBVOT, and AOBVOT groups, respectively (P < 0.001). NPC decreased (improved) by 86%, 89%, and 96% in the HBVOT, OBVOT, and AOBVOT groups, respectively (P = 0.4). The CISS scores decreased by 75%, 96%, and 100% in the HBVOT, OBVOT, and AOBVOT groups, respectively (P = 0.003).

Conclusion:

Our results showed that in adults with CI, the augmented office-based orthoptic treatment was relatively more effective than the other treatments.

Orthoptic Treatment of Convergence Insufficiency in Parkinson's Disease: A Case Series

Introduction: This study reports a case series of orthoptic treatment (OT) for convergence insufficiency (CI) in individuals with Parkinson's disease (PD). Method: We are reporting two cases of individuals with PD who completed OT for CI. Both had a confirmed diagnosis of CI, accompanied by CI-type symptomatology. They each underwent an OT program consisting of three office-based visits and 8 weeks of home-based exercises. Treatment outcome was based on the changes measured pre- versus post-OT on the near point of convergence, positive fusional vergences, and symptomatology score. Results: The two participants successfully completed therapy, gained ability to converge, had fewer symptoms, and were satisfied with the OT-induced changes they felt in their day-to-day lives. Conclusion: This case series show that OT for CI in PD is possible. Further research is required as these results demonstrate that OT has the potential to improve symptomatic CI in these patients. In the meantime, the positive results obtained in these two cases should encourage clinicians to consider OT (a therapy with no/minimal risk) for CI in patients with PD whose quality of life is affected by this binocular dysfunction.

Near Point of Convergence After a Sport-Related Concussion: Measurement Reliability and Relationship to Neurocognitive Impairment and Symptoms

BACKGROUND

Convergence insufficiency (CI) is a common binocular vision deficit after a sport-related concussion (SRC). CI may result in visual discomfort and vision-mediated functional difficulties such as slowed reading and compromised attention, leading to impaired academic, work, and sport performance.

PURPOSE

To test the reliability of repeated near point of convergence (NPC) measurements in a sample of athletes after an SRC; compare the symptoms and cognitive impairment of athletes with normal NPC to those with CI after an SRC; and explore the relationship among age, sex, learning disability, migraine history, and CI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 78 athletes (mean age, 14.31 ± 2.77 years) who were seen a mean 5.79 ± 5.63 days after an SRC were administered 3 trials of an NPC assessment, along with neurocognitive (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]) and symptom assessments. Patients were divided into normal NPC (NPC ≤ 5 cm; n = 45) and CI (NPC >5 cm; n = 33) groups. Intraclass correlation coefficients (ICCs) and repeated-measures analyses of variance (ANOVAs) assessed the consistency of NPC across the 3 trials. The ANOVAs were employed to examine differences on neurocognitive composites and symptoms between the normal NPC and CI groups. Stepwise regressions (controlling for age and symptom scores on the Post-Concussion Symptom Scale [PCSS]) were conducted to evaluate the predictive utility of the NPC distance for neurocognitive impairment.

RESULTS

Groups did not differ on demographic or injury characteristics. NPC differed between trial 1 and trials 2 (P = .02) and 3 (P = .01) for the CI group but not the normal NPC group. Internal consistency was high across NPC measurements (ICC range, 0.95-0.98). Patients with CI performed worse on verbal memory (P = .02), visual motor speed (P = .02), and reaction time (P = .001, η(2) = .13) and had greater total symptom scores (P = .02) after the injury. Results of hierarchical regression revealed that the NPC distance contributed significantly to the model for reaction time (P < .001).

CONCLUSION

CI was common (~42%) in athletes evaluated within 1 month after an SRC. Athletes with CI had worse neurocognitive impairment and higher symptom scores than did those with normal NPC. Clinicians should consider routinely screening for NPC as part of a comprehensive concussion evaluation to help inform treatment recommendations, academic accommodations, and referrals for vision therapy.

Increased onset of vergence adaptation reduces excessive accommodation during the orthoptic treatment of convergence insufficiency

This research tested the hypothesis that the successful treatment of convergence insufficiency (CI) with vision-training (VT) procedures, leads to an increased capacity of vergence adaptation (VAdapt) allowing a more rapid downward adjustment of the convergence accommodation cross-link. Nine subjects with CI were recruited from a clinical population, based upon reduced fusional vergence amplitudes, receded near point of convergence or symptomology. VAdapt and the resulting changes to convergence accommodation (CA) were measured at specific intervals over 15 min (pre-training). Separate clinical measures of the accommodative convergence cross link, horizontal fusion limits and near point of convergence were taken and a symptomology questionnaire completed. Subjects then participated in a VT program composed of 2.5h at home and 1h in-office weekly for 12-14 weeks. Clinical testing was done weekly. VAdapt and CA measures were retaken once clinical measures normalized for 2 weeks (mid-training) and then again when symptoms had cleared (post-training). VAdapt and CA responses as well as the clinical measures were taken on a control group showing normal clinical findings. Six subjects provided complete data sets. CI clinical findings reached normal levels between 4 and 7 weeks of training but symptoms, VAdapt, and CA output remained significantly different from the controls until 12-14 weeks. The hypothesis was retained. The reduced VAdapt and excessive CA found in CI were normalized through orthoptic treatment. This time course was underestimated by clinical findings but matched symptom amelioration.

Can vergence training improve reading in dyslexics?

BACKGROUND

Dyslexia affects 5%-8% of the population of the Western world. While reading, different eye movements are required. Compared to other persons, dyslexics have more and longer fixations, shorter saccade amplitude, a higher percentage of regression, and more fixation disparity when reading. In non-reading situations, dyslexics do not have more binocular problems than others. The aim of the present study was to investigate whether computerized orthoptic vergence training could improve reading ability for dyslexic children.

METHODS

The study was conducted at Ängkärrskolan, Solna, an elementary school exclusively for dyslexic children. Twelve subjects, aged 13-14 years, were trained with RetCorr, a computerized vergence training program. Reading speed was assessed before and after treatment. The results were compared with an age-matched control group.

RESULTS

The dyslexic subjects conducted on average 11.75 sessions (±2.53 SD) of orthoptic training over a 5-week period. On average, the number of words read per minute before training were 87.83 (±16.80 SD) and after training 95.58 words (±18.08 SD). The difference was statistically significant (p=0.0066). In the control group, the change was from 85.00 (±19.68 SD) words to 89.37 words (±19.71 SD) over the same time period. This difference was not significant (p=0.1235).

DISCUSSION

Most scientists agree that dyslexia is mainly a phonological impairment. Nevertheless, the results show that vergence treatment might help dyslexics. Larger studies are required to provide guidance in this area.

Task-modulated coactivation of vergence neural substrates

While functional magnetic resonance imaging (fMRI) has identified which regions of interests (ROIs) are functionally active during a vergence movement (inward or outward eye rotation), task-modulated coactivation between ROIs is less understood. This study tested the following hypotheses: (1) significant task-modulated coactivation would be observed between the frontal eye fields (FEFs), the posterior parietal cortex (PPC), and the cerebellar vermis (CV); (2) significantly more functional activity and task-modulated coactivation would be observed in binocularly normal controls (BNCs) compared with convergence insufficiency (CI) subjects; and (3) after vergence training, the functional activity and task-modulated coactivation would increase in CIs compared with their baseline measurements. A block design of sustained fixation versus vergence eye movements stimulated activity in the FEFs, PPC, and CV. fMRI data from four CI subjects before and after vergence training were compared with seven BNCs. Functional activity was assessed using the blood oxygenation level dependent (BOLD) percent signal change. Task-modulated coactivation was assessed using an ROI-based task-modulated coactivation analysis that revealed significant correlation between the FEF, PPC, and CV ROIs. Prior to vergence training, the CIs had a reduced BOLD percent signal change compared with BNCs for the CV (p<0.05), FEFs, and PPC (p<0.01). The BOLD percent signal change increased within the CV, FEF, and PPC ROIs (p<0.001) as did the task-modulated coactivation between the FEFs and CV as well as the PPC and CV (p<0.05) when comparing the CI pre- and post-training datasets. Results from the Convergence Insufficiency Symptom Survey were correlated to the percent BOLD signal change from the FEFs and CV (p<0.05).

Reduced vergence adaptation is associated with a prolonged output of convergence accommodation in convergence insufficiency

Convergence insufficiency (CI) is a developmental visual anomaly defined clinically by a reduced near point of convergence, a reduced capacity to view through base-out prisms (fusional convergence); coupled with asthenopic symptoms typically blur and diplopia. Experimental studies show reduced vergence parameters and tonic adaptation. Based upon current models of accommodation and vergence, we hypothesize that the reduced vergence adaptation in CI leads to excessive amounts of convergence accommodation (CA). Eleven CI participants (mean age=17.4±2.3 years) were recruited with reduced capacity to view through increasing magnitudes of base out (BO) prisms (mean fusional convergence at 40 cm=12±0.9Δ). Testing followed our previous experimental design for (n=11) binocularly normal adults. Binocular fixation of a difference of Gaussian (DoG) target (0.2 cpd) elicited CA responses during vergence adaptation to a 12Δ BO. Vergence and CA responses were obtained at 3 min intervals over a 15 min period and time course were quantified using exponential decay functions. Results were compared to previously published data on eleven binocular normals. Eight participants completed the study. CI's showed significantly reduced magnitude of vergence adaptation (CI: 2.9Δ vs. normals: 6.6Δ; p=0.01) and CA reduction (CI=0.21 D, Normals=0.55 D; p=0.03). However, the decay time constants for adaptation and CA responses were not significantly different. CA changes were not confounded by changes in tonic accommodation (Change in TA=0.01±0.2D; p=0.8). The reduced magnitude of vergence adaptation found in CI patients resulting in higher levels of CA may potentially explain their clinical findings of reduced positive fusional vergence (PFV) and the common symptom of blur.

The effect of visual therapy on the ocular motor control of seven- to eight-year-old children with developmental coordination disorder (DCD)

The aims of this study were to determine the extent of ocular, motor control problems and the effect of visual therapy on such problems, among seven- to eight-year-old children diagnosed with DCD. Thirty-two, children with a mean age of 95.66 months (SD ± 3.54) participated in the study. The MABC was used to classify children into DCD categories (<15th, percentile) while the Sensory Input Systems Screening Test and QNST-II, were used to evaluate ocular motor control. A two-group pre-test-post-test, cross-over design was followed with a retention test two years, thereafter to determine the lasting effect of the visual therapy, intervention. The 18-week visual therapy programme was executed once a week, for 40 min during school hours, after which the two groups were, crossed over. Percentages of ocular motor control problems ranging, between 6.25% and 93.75% were found in both the groups before participating, in the visual therapy programme, with the highest percentage problems found, in visual pursuit with the left eye. Visual therapy contributed to a, significant improvement of 75-100% in visual pursuit, fixation, ocular, alignment and convergence, with significant lasting effects (p<0.001). Visual therapy is recommended for children with DCD experiencing poor, ocular motor control.

Diagnostic validity of clinical signs associated with a large exophoria at near

Purpose. To analyze the diagnostic validity of accommodative and binocular tests in a sample of patients with a large near exophoria with moderate to severe symptoms. Methods. Two groups of patients between 19 and 35 years were recruited from a university clinic: 33 subjects with large exophoria at near vision and moderate or high visual discomfort and 33 patients with normal heterophoria and low visual discomfort. Visual discomfort was defined using the Conlon survey. A refractive exam and an exhaustive evaluation of accommodation and vergence were assessed. Diagnostic validity by means of receiver operator characteristic (ROC) curves, sensitivity (S), specificity (Sp), and positive and negative likelihood ratios (LR+, LR-) were assessed. This analysis was also carried out considering multiple tests as serial testing strategy. Results. ROC analysis showed the best diagnostic accuracy for receded near point of convergence (NPC) recovery (area = 0.929) and binocular accommodative facility (BAF) (area = 0.886). Using the cut-offs obtained with ROC analysis, the best diagnostic validity was obtained for the combination of NPC recovery and BAF (S  =  0.77, Sp = 1, LR+ = value tending to infinity, LR- = 0.23) and the combination of NPC break and recovery with BAF (S  =  0.73, Sp = 1, LR+ = tending to infinity, LR- = 0.27). Conclusions. NPC and BAF tests were the tests with the best diagnostic accuracy for subjects with large near exophoria and moderate to severe symptoms.

Ten-year changes in fusional vergence, phoria, and nearpoint of convergence in myopic children

PURPOSE

To identify longitudinal changes in fusional vergence ranges and their relationship to other clinical measures in young myopic subjects.

METHODS

Measurements were collected annually for 10 years on 114 subjects from the University of Houston Correction of Myopia Evaluation Trial cohort. Subject age was 7 to 13 years at year 1 of follow-up. Measurements included refractive error, distance and near phoria, interpupillary distance (IPD), prism bar fusional vergence ranges, and nearpoint of convergence (NPC). Multilevel modeling was used to determine baseline and rate of change for fusional vergence ranges and the impact of phoria, IPD, and NPC on these measures.

RESULTS

Year 1 mean distance base-out (BO) break was 20 prism diopters (pd) and decreased 5.6 pd over 10 years (p < 0.001). Mean near BO break was 30 pd at year 1 and decreased 9.4 pd over 10 years (p < 0.001). Greater esophoria was significantly related to greater BO break (p < 0.02) and receded NPC was significantly related to lower magnitude BO break at near (p < 0.001). Distance IPD increased 3 mm over 10 years (p < 0.001) but was unrelated to the magnitude of the BO ranges (p > 0.2). Mean distance base-in (BI) break was 7 pd at year 1 and increased 0.5 pd in 10 years (p = 0.04). Mean near BI break was 13 pd at year 1 and did not significantly change. Mean distance phoria was 0.1 pd exophoria at year 1 and did not change, whereas near phoria was 2.4 pd esophoria at year 1 and became more exophoric (4 pd in 10 years, p < 0.001).

CONCLUSIONS

These results suggest that for myopic children convergence ranges decrease for both distance and near viewing during the school years as near phoria becomes more exophoric. These findings could have clinical implications given that compensating convergence ranges decrease as near phoria becomes more divergent.

Vision therapy for basic exotropia in adults: 2 case studies

BACKGROUND

Basic exotropia accounts for approximately 50% of all intermittent exotropias. Many clinicians view treating these patients, especially adults with childhood-onset exotropia, as challenging. Conflicting opinions still exist regarding prescribing any treatment for adult strabismics, including surgical realignment and optometric vision therapy (VT).

CASE REPORTS

Two cases are discussed, both of which are adult patients with moderate-size intermittent exotropia of the basic type who presented with asthenopia, headaches, and/or diplopia. Twenty to 30 in-office VT sessions were recommended to reduce the magnitude and frequency of the deviation as well as improve their binocularity and decrease their symptoms. After completing VT, both patients became phoric for all distances, had normal vergence ability, and had normal near points of convergence. In the second case, the long-term outcome was evaluated 5 years post-therapy.

CONCLUSION

Optometric VT was highly successful in both patients with childhood intermittent exotropia of the basic type. Most important, optometric VT eliminated the patients' symptoms of asthenopia and diplopia without the need for surgery.

Treatment of symptomatic convergence insufficiency with a home-based computer orthoptic exercise program

PURPOSE

To determine the efficacy of a home-based computer orthoptic program to treat symptomatic convergence insufficiency.

METHODS

A retrospective review of consecutive patients with symptomatic convergence insufficiency treated with a home-based computer orthoptic program was performed. Symptomatic convergence insufficiency was defined as: near point of convergence (NPC) >6 cm, decreased positive fusional vergence, exophoria at near at least 4(Δ) greater than at far, and documented complaints of asthenopia, diplopia, or headaches with reading or near work. The Computer Orthoptics CVS program was used for this study. Before beginning the computer orthoptic program, patients with an NPC >50 cm were given 4 base-in prisms and push-up exercises (NPC exercises with an accommodative target) for 2 weeks.

RESULTS

A total of 42 patients were included. Mean treatment duration was 12.6 weeks; mean follow-up, 8.5 months. Of the 42 patients, 35 were treated with the home-based computer orthoptic program and push-up exercises; the remaining 7 only used the computer orthoptic program. Because of a remote NPC, 5 patients were given base-in Fresnel prism before starting treatment. Baseline mean NPC was 24.2 cm; posttreatment mean NPC improved to 5.6 cm: 39 patients (92.8%) achieved an NPC of ≤6 cm (p < 0.001). Positive fusional vergence improved in 39 patients (92.8%). Fourteen patients reduced their near exophoria by ≥5(Δ). A total of 27 patients (64.2%) reported resolution of symptoms after treatment.

CONCLUSIONS

In our study, home-based computer orthoptic exercises reduced symptoms and improved NPC and fusional amplitudes. The computer orthoptic program is an effective option for treating symptomatic convergence insufficiency.

Visual problems among video display terminal (VDT) users in Nepal

Purpose

To evaluate visual problems, major symptoms, and their associations among VDT users in Nepal.

Methods

Among 76 hospital attendees, assessment included visual acuity, retinoscopy, convergence, accommodation, fusional vergence and Schirmer's II. Subjects’ symptoms were recorded in the structured 5 point intensity scale questionnaire.

Results

Mean age of subjects was 25.8 ± 5 years with 6.9 ± 2.6 hours/day of computer use. Ocular changes were reported in 92.1% of the total subjects. The common ocular change was accommodative infacility. The most common symptoms (p < 0.001) were tired eye and headache. Reduced tear secretion as indicated by Schirmer's test II was found to have a little role in manifesting the symptoms as indicated by regression coefficient.

Conclusions

Accommodative infacility and tired eye were the most common abnormalities and symptom reported. Schirmer's test II was slightly correlated with some ocular, visual, and systemic symptoms.

Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures

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.

Non-surgical interventions for convergence insufficiency

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.

Convergence insufficiency and its current treatment

PURPOSE OF REVIEW

Considerable uncertainty and controversy has existed concerning the management of convergence insufficiency. Only recently there have been significant scientific studies published that compare the effectiveness of the commonly prescribed treatments. This paper reviews the most recent research and literature on convergence insufficiency and its treatment.

RECENT FINDINGS

The first large-scale placebo-controlled, randomized clinical trials to study the various treatments of convergence insufficiency have recently been published. Current research compares the effectiveness of base-in prism glasses, pencil push-ups, and vision therapy in reducing the signs and symptoms of convergence insufficiency and suggests that orthoptic therapy is the most efficacious treatment for convergence insufficiency.

SUMMARY

Intensive orthoptic therapy is the treatment of choice for convergence insufficiency. Pencil push-ups and use of accommodative targets have a role in the treatment of convergence insufficiency when used as part of a more intensive orthoptic program. Base-in prism glasses should be reserved for reduction of symptoms in the presbyopic population.

Treatment of accommodative and nonstrabismic binocular dysfunctions: a systematic review

BACKGROUND

The aim of this study was to analyze the scientific evidence available on the nonsurgical treatment of accommodative and nonstrabismic binocular dysfunctions, identifying the types of treatment used and their efficacy.

METHODS

A systematic review of reports published from 1986 to 2007 was completed using several health science databases: FRANCIS, Medline, Cinahl, and PsycINFO. Those papers that analyzed the treatment of accommodative and nonstrabismic binocular anomalies were included.

RESULTS

Of the 565 articles identified, 16 met the inclusion criteria. Only 3 were clinical trials. All analyzed treatment of convergence insufficiency. Results of clinical trials support the conclusion that vision therapy improves symptoms and signs for convergence insufficiency. Further, the evidence indicates that pencil push-up treatment is not as effective as vision therapy and that prism glasses are no more effective than placebo glasses. For the other nonstrabismic binocular conditions and accommodative disorders, there is a lack of published randomized, clinical trials that support the evidence for the efficacy of each treatment.

CONCLUSION

Scientific evidence exists for the efficacy of vision therapy for convergence insufficiency. Insufficient scientific evidence exists on the best therapeutic options for treatment of the other nonstrabismic binocular anomalies and accommodative disorders.

Treatment of convergence insufficiency in childhood: a current perspective

PURPOSE

To provide a current perspective on the management of convergence insufficiency (CI) in children by summarizing the findings and discussing the clinical implications from three recent randomized clinical trials in which we evaluated various treatments for children with symptomatic CI. We then present an evidence-based treatment approach for symptomatic CI based on the results of these trials. Finally, we discuss unanswered questions and suggest directions for future research in this area.

METHODS

We reviewed three multi-center randomized clinical trials comparing treatments for symptomatic (CI) in children 9 to 17 years old (one study 9 to 18 years old). Two trials evaluated active therapies for CI. These trials compared the effectiveness of office-based vergence/accommodative therapy, office-based placebo therapy, and home-based therapy [pencil push-ups alone (both trials), home-based computer vergence/accommodative therapy, and pencil push-ups (large-scale study)]. One trial compared the effectiveness of base-in prism reading glasses to placebo reading glasses. All studies included well-defined criteria for the diagnosis of CI, a placebo group, and masked examiners. The primary outcome measure was the Convergence Insufficiency Symptom Survey score. Secondary outcomes were near point of convergence and positive fusional vergence at near.

RESULTS

Office-based vergence/accommodative therapy was significantly more effective than home-based or placebo therapies. Base-in prism reading glasses were no more effective than placebo reading glasses for the treatment of symptomatic CI in children.

CONCLUSIONS

Recent clinical trials showed that office-based vision therapy was successful in about 75% of patients (resulting in normal or significantly improved symptoms and signs) and was the only treatment studied which was more effective than placebo treatments for children with symptomatic CI. Eye care providers who do not currently offer this treatment may consider referring these patients to a doctor who provides this treatment or consider expanding the treatment options available within their practice to manage this condition.

Are Orthoptic Exercises an Effective Treatment for Convergence and Fusion Deficiencies?

PURPOSE

To investigate whether orthoptic exercises are an effective way to influence the near point of convergence, fusion range and asthenopic symptoms.

METHODS

Seventy-eight patients met the inclusion criteria of visual acuity 6/9 or better, no history of orthoptic treatment, squint surgery or Meares Irlen syndrome/dyslexia. Information was collected from case records related to diagnosis, near point of convergence, fusion range, prism and cover test measurements and symptoms. Type, duration and frequency of exercises were also recorded. Non-parametric statistics were applied.

RESULTS

Patients ranged in age from 5 to 73 years (mean 11.9). Females outnumbered males (46:32). The diagnoses were: decompensating heterophoria (n = 50) or convergence insufficiency (n = 28: primary 27; secondary 1). Exophoria was more common (n = 65), than esophoria (n = 11) or orthophoria (n = 1). Treatments were aimed at improving near point of convergence and/or reduced fusional reserves. The mean treatment period was 8.2 months. Reduced near point of convergence normalized following treatment in 47/55 cases, and mean near point of convergence improved from 16.6 to 8.4 cm (p = 0.0001). Fusional reserves normalized in 29/50. Fusional convergence improved significantly for those with exodeviation (p > 0.0006). Asthenopic symptoms improved in 65 patients. A reduction in deviation of 5 pd or more occurred in 20 patients.

CONCLUSIONS

Orthoptic exercises are an effective means of reducing symptoms in patients with convergence insufficiency and decompensating exophoria, and appear to target the proximal and fusional components of convergence. Their role in esophoria is unclear and needs further study.

Preferred clinical practice in convergence insufficiency in India: a survey

Purpose

Convergence insufficiency (CI) is a common binocular vision disorder. However, there is a lack of consensus regarding the treatment most appropriate for CI. The aim of the study was to investigate the treatment for CI by surveying the ophthalmologists regarding the most common treatment modalities used in India.

Materials and Methods:

Four hundred questionnaires were distributed amongst ophthalmologists attending different sessions of the Delhi Ophthalmological Society annual conference held in April 2007. Two hundred and three ophthalmologists responded (response rate 50.75%). The responders included 109 private practitioners, 57 consultants attached to teaching institutes and 37 residents.

Results:

The majority of ophthalmologists (66.7%) claimed encountering >5% outpatient department patients with CI. Pencil push-ups therapy (PPT) was the most common first line of treatment offered by ophthalmologists (79%) followed by synoptophore exercises (18%). Only 3% referred the patients to optometrists. Thirty per cent ophthalmologists claimed good results with PPT, which was significantly higher in private practitioners (35%). Only 26% ophthalmologists explained physiological diplopia to patients on a regular basis and reported significantly higher percentage of patients (46.3%) with good results. Only 12.3% ophthalmologists needed to refer >30% patients for synoptophore exercises. For failure of PPT 86.7% considered lack of compliance as the major reason as perceived by ophthalmologists.

Conclusions:

This survey suggested that most ophthalmic practitioners prescribed PPT as the initial treatment for CI and had satisfactory results with PPT. The majority of the practitioners did not explain to the patient about physiological diplopia. Explaining physiological diplopia may improve outcome, as perceived from the survey.

The convergence insufficiency treatment trial: design, methods, and baseline data

OBJECTIVE

This report describes the design and methodology of the Convergence Insufficiency Treatment Trial (CITT), the first large-scale, placebo-controlled, randomized clinical trial evaluating treatments for convergence insufficiency (CI) in children. We also report the clinical and demographic characteristics of patients.

METHODS

We prospectively randomized children 9 to 17 years of age to one of four treatment groups: 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, 4) office-based placebo therapy. Outcome data on the Convergence Insufficiency Symptom Survey (CISS) score (primary outcome), near point of convergence (NPC), and positive fusional vergence were collected after 12 weeks of active treatment and again at 6 and 12 months posttreatment.

RESULTS

The CITT enrolled 221 children with symptomatic CI with a mean age of 12.0 years (SD = +2.3). The clinical profile of the cohort at baseline was 9Delta exophoria at near (+/- 4.4) and 2Delta exophoria (+/-2.8) at distance, CISS score = 30 (+/-9.0), NPC = 14 cm (+/- 7.5), and near positive fusional vergence break = 13 Delta (+/- 4.6). There were no statistically significant nor clinically relevant differences between treatment groups with respect to baseline characteristics (p > 0.05).

CONCLUSION

Hallmark features of the study design include formal definitions of conditions and outcomes, standardized diagnostic and treatment protocols, a placebo treatment arm, masked outcome examinations, and the CISS score outcome measure. The baseline data reported herein define the clinical profile of those enrolled into the CITT.

Eyelid Squint Response to Asthenopia-Inducing Conditions

PURPOSE

To study the orbicularis oculi muscle response to asthenopia-inducing conditions.

METHODS

Twenty subjects (18-36 years) screened for 20/20 vision in each eye participated in the study. Subjects read passages under different asthenopia-inducing conditions. The inducing conditions were glare, low contrast, small font size, refractive error, up gaze, accommodative stress and convergence stress. Surface electromyography (EMG) was used to study the orbicularis oculi response from the right eye. Palpebral fissure height was measured from recorded video images of the right eye. At the end of each condition subjects were asked to rate the severity and type of visual discomfort experienced.

RESULTS

Outcome measures for the asthenopia-inducing conditions were compared with their respective nonstress controls. Repeated measures analysis of variance was used to analyze the data. Refractive error (p = 0.0001), glare (p = 0.0001), low contrast (p = 0.007), small font (p = 0.034), and up gaze (p = 0.001) resulted in a significant increase in EMG power. Refractive error (p = 0.0001) and glare (p = 0.0001) also caused significant reduction in aperture size. Reading a low contrast text caused a reduction in blink rate (p = 0.035), whereas refractive error (p = 0.005) and glare (p = 0.01) caused an increase in blink rate. All conditions induced significant visual discomfort (p < 0.001).

CONCLUSION

Refractive error and glare, which reduce image quality and benefit from eyelid squint, caused increased EMG power, eyelid squint response and increased blink rate. Low contrast and small font, which reduce image quality but do not benefit from eyelid squint, resulted in increased EMG power without changes in aperture size and reduced blink rate (for low contrast). Accommodative and convergence stress (in subjects with normal accommodative and vergence abilities) did not cause changes in EMG power, aperture size or blink rate. These results suggest that contraction of the orbicularis oculi is a part of the asthenopia mechanism related to compromised image quality.

A prospective study of the EYEPORT vision training system

BACKGROUND

The purpose of this study was to determine if vision training with the EYEPORT system affects vision and reading performance. (Subsequent to this study, the "E.Y.E." has been renamed "EYEPORT")

METHODS

College students with normal vision (n = 31) participated in a blind, crossover study to assess within-subject and between-group effects of EYEPORT training. Half the subjects initially underwent training (10 minutes per day, 6 days a week for 3 weeks), and then crossed over to the no-train control condition (3 weeks); the other half underwent the reverse sequence. Vision and reading performance were assessed at baseline, 3 weeks, and 6 weeks.

RESULTS

Multivariate analyses (Hotelling's T2) found small improvements in vergence and accommodative facility, reading performance, and stereopsis response time after EYEPORT training (P < 0.025). Enhancements in reading performance and vergence facility were still present 3 weeks after cessation of training (P < 0.001).

CONCLUSIONS

The EYEPORT training system shows potential to enhance visual performance and reading ability. Studies are underway to assess its efficacy in symptomatic populations.

A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults

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.

A systematic review of the applicability and efficacy of eye exercises

PURPOSE

To examine the current scientific evidence base regarding the efficacy of eye exercises as used in optometric vision therapy.

METHODS

A search was performed of the following databases: Allied and Complementary Medicine Database, Cochrane Database of Systematic Reviews, Cochrane Register of Controlled Trials, EMBASE, and MEDLINE. Relevant articles were reviewed and analyzed for strengths and weaknesses. Pertinent sections of classic texts were studied to provide a historical basis and to serve as a source for additional early references.

RESULTS

Forty-three refereed studies were obtained. Of these, 14 were clinical trials (10 controlled studies), 18 review articles, 2 historical articles, 1 case report, 6 editorials or letters, and 2 position statements from professional colleges. Many of the references listed by the larger reviews were unpublished or published in obscure or nonrefereed sources and therefore were not accessible.

CONCLUSIONS

Eye exercises have been purported to improve a wide range of conditions including vergence problems, ocular motility disorders, accommodative dysfunction, amblyopia, learning disabilities, dyslexia, asthenopia, myopia, motion sickness, sports performance, stereopsis, visual field defects, visual acuity, and general well-being. Small controlled trials and a large number of cases support the treatment of convergence insufficiency. Less robust, but believable, evidence indicates visual training may be useful in developing fine stereoscopic skills and improving visual field remnants after brain damage. As yet there is no clear scientific evidence published in the mainstream literature supporting the use of eye exercises in the remainder of the areas reviewed, and their use therefore remains controversial.

Convergence insufficiency: a treatable cause of problems in microsurgery

Microsurgical training concentrates on the practical mechanisms of performing vessel anastomoses, with little attention given to medical problems that may adversely affect the trainee's performance. Undiagnosed vision problems are rarely considered in microsurgical training, and may not be manifested until other limiting factors, such as basic instrument and suture handling, are mastered. While vision problems tend to be diagnosed and treated immediately among ophthalmology trainees, visual and ocular pathology is poorly understood outside of that specialty. We present a case of a surgeon who had been performing microsurgery for 10 years with an undiagnosed binocular vision problem that consistently affected microsurgical proficiency. Once diagnosed, the problem responded to therapeutic exercises within weeks. We suggest ophthalmologic referral of any surgeon who has unexplained problems with microsurgical technique (especially problems involving stereoscopic vision) to exclude a treatable visual cause.

Is all asthenopia the same?

PURPOSE

Any of several conditions can cause asthenopia. The purpose of this study was to determine whether the particular sensations or their location vary dependent on the symptom-inducing condition.

METHODS

Twenty subjects with good vision performed eight reading tasks in random order during different conditions. Each condition used different stimuli to induce asthenopia. The eight conditions were mixed astigmatism, close viewing distance, upward gaze, dry eyes, lens flipper, small font, glare, and flickering light. Subjects were asked to read until attaining a level of discomfort self-defined as "barely tolerable." After each task, subjects rated the magnitude of several symptom descriptors (burning, ache, strain, irritation, tearing, blurred vision, double vision, dryness, and headache) and their location.

RESULTS

Analysis of variance with repeated measures was used to determine that all of the individual symptom sensation measures (except blur) were significantly related (p values ranged from 0.003 to <0.0001) to the inducing condition. Principal factor analysis with orthogonal varimax rotation was used to test symptom by condition relationships and determined two latent factors, designated external and internal symptom factors (ESF and ISF), that related symptoms to inducing condition. The ESF pattern comprises burning, irritation, tearing, and dryness located in the front and bottom of the eye. ESF is caused by holding the eyelid open, glare, up gaze, small font, and flickering. ESF seems highly related to dry-eye symptoms. The ISF pattern comprises ache, strain, and headache located behind the eyes. ISF is caused by the close viewing distance, lens flipper, and mixed astigmatism conditions and is likely related to accommodative and vergence stress.

CONCLUSIONS

Symptom descriptors and locations were able to distinguish discomfort on the basis of causative condition. Results support two different symptom constellations and, hence, at least two different afferent pathways for symptoms of asthenopia.

Nearpoint of convergence: test procedure, target selection, and normative data

BACKGROUND

The purpose of this study was to help determine the most appropriate target to be used for the assessment of the nearpoint of convergence, normative data for the break and recovery in adults, and the diagnostic value of the red-glass modification and repetition of the nearpoint of convergence.

METHODS

A total of 175 subjects with normal binocular vision and 38 subjects with convergence insufficiency were evaluated. The nearpoint of convergence was measured three ways, with an accommodative target, a penlight, and a penlight with red and green glasses. The nearpoint of convergence was also measured using a penlight for 10 repetitions.

RESULTS

Results suggest a clinical cutoff value of 5 cm for the nearpoint of convergence break and 7 cm for the nearpoint of convergence recovery with either an accommodative target or a penlight with red and green glasses.

CONCLUSION

This study establishes normative data for the nearpoint of convergence break and recovery in the adult population and supports the value of various test modifications when other testing is equivocal.

Efficacy of treatment for convergence insufficiency using vision therapy

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.

The effectiveness of pencil pushups treatment for convergence insufficiency: a pilot study

PURPOSE

To study the effectiveness of pencil pushups treatment (PPT) for the treatment of convergence insufficiency in a clinical situation.

METHODS

PPT was prescribed for use at home for 6 weeks for 25 subjects with convergence insufficiency.

RESULTS

Twelve of the subjects returned for follow-up. Seven of 12 (58%) subjects showed a clinically significant improvement in nearpoint of convergence and positive fusional vergence, and 11 of 12 reported improvement in symptoms. Only one subject became asymptomatic.

CONCLUSIONS

PPT resulted in some improvement in both objective findings and symptoms for some subjects. Compliance with the recommended home therapy protocol was poor.

A survey of treatment modalities for convergence insufficiency

BACKGROUND

Convergence insufficiency (CI) is a common and distinct binocular vision disorder. However, there is a lack of consensus regarding the treatment most appropriate for Cl. Possible treatment modalities include base-in prism, pencil pushup therapy (PPT), reading glasses, home-based vision therapy/orthoptics (HBVT), and office-based vision therapy/orthoptics (OBVT). The purpose of this study was to investigate the care process for Cl by surveying eyecare professionals regarding the most common treatment modalities used by both optometrists and ophthalmologists across the United States.

METHODS

Surveys requesting doctors to indicate which treatment(s) they prescribed and believed to be most effective for symptomatic CI patients were mailed to 863 optometrists and 863 ophthalmologists in the United States.

RESULTS

Fifty-eight percent of the optometrists responded to the survey; the most common treatment prescribed was PPT (36%) followed by HBVT (22%) and OBVT (16%). For the ophthalmologists (who had a 23% response rate), the most common treatment prescribed was PPT (50%) followed by HBVT (21 %) and base-in prism (10%).

CONCLUSIONS

This survey suggests that most eyecare practitioners prescribe PPT as the initial treatment for CI.

Medial rectus resection(s) with adjustable suture for intermittent exotropia of the convergence insufficiency type

BACKGROUND

The surgical results for intermittent exotropia of the convergence insufficiency type have been reported to be of varying success. The purpose of this study is to evaluate the surgical results of medial rectus muscle (MR) resection(s) with adjustable suture for this condition.

METHODS

Twenty-one consecutive patients with intermittent exotropia of the convergence insufficiency type were included in this retrospective study. All patients had a history of prolonged difficulties at near work unrelieved by nonsurgical treatment. Unilateral or bilateral MR resection(s) were done with the adjustable suture, which was tied at the first postoperative day. The target angle was an esotropia of 10 to 20 PD at distance and an esotropia of 5 to 10 PD at near. Postoperatively Fresnel prisms were used temporarily in patients manifesting a consecutive esotropia with diplopia at distance. Postoperative follow-up period was between 6 months and 24 months with a mean of 9.1 months.

RESULTS

MR resection(s) with the adjustable suture reduced the mean exodeviation at near from 25.7 to 3 PD. It also reduced the exodeviation at distance from 11.4 to -2 PD (esodeviation). The mean near-distance difference was collapsed from 14.3 PD preoperatively to 5 PD postoperatively.

CONCLUSIONS

MR resection(s) with adjustable suture combined with intentional postoperative aggressive overcorrection and the use of Fresnel prisms is useful in intermittent exotropia of the convergence insufficiency type. The intentional overcorrection during the immediate postoperative period at distance and near is required to prevent long-term undercorrection.

Abnormal supranuclear eye movements in the child: a practical guide to examination and interpretation

Abnormal eye movements in the infant or voting child can be congenital or acquired. They may be a result of abnormal early visual development or a sign of underlying neurologic or neuromuscular disease. It is important to be able to detect these abnormalities and to distinguish them from normal but immature eye movements. The spectrum of disease in children differs from that in adults. Serious, potentially fatal but treatable disorders can be acquired in infancy, and abnormal eye movements in a sometimes apparently well child should never be labeled as congenital or benign without careful investigation. Eye movement analysis can indicate the presence of an underlying condition and help the clinician to classify different neurologic diseases. It is important to carefully examine the ocular motor system in any children at risk of neurologic disease. This review provides a practical guide to the examination and interpretation of eye movements in the child and includes recent literature on eye movement disorders of childhood. We describe supranuclear abnormalities of the ocular motor system in the order in which we would normally examine it: saccades, pursuit, convergence, vestibulo-ocular reflex, and optokinetic nystagmus. Nystagmus, internuclear ophthalmoplegia, cranial nerve abnormalities, and "miswiring" phenomena (such as Duane's syndrome and synergistic divergence) are not discussed.

Gaze-shift dynamics in subjects with and without symptoms of convergence insufficiency: influence of monocular preference and the effect of training

We studied gaze-shift dynamics during several gaze-shift tasks and during reading, in five subjects with convergence insufficiency (C.I., a diminished ability to converge), and in ten subjects without C.I. Furthermore, we studied the effect of vergence training in order to verify previous claims that orthoptic exercises can improve vergence performance. We recorded binocular eye movements with the scleral coil technique. Subjects switched fixation between nearby and distant light emitting diodes (LEDs) arranged in isovergence arrays (distances 35 and 130 cm) in a dimly lit room. In both the C.I. and non-C.I. group, two classes of subjects occurred: vergence responders and saccadic responders. During pure vergence tasks, saccadic responders made saccades with no or little vergence; vergence responders made vergence movements with no or small saccadic components. In saccadic responders, fixation of nearby targets was monocular. Subjects with a preferred eye, according to our determination, used the preferred eye. The five C.I. subjects showed idiosyncratic responses with insufficient vergence during most trials. They all had a tendency to alternate fixation between the left and right eye. Vergence-version tasks always elicited larger vergence components than pure vergence tasks. During a reading task, vergence angles were more accurate than during gaze-shifts between LEDs. After the pre-training sessions, nine subjects (one of which had C.I.) practised a pure vergence task three times a day for at least 2 weeks. Vergence amplitudes of four of these subjects were larger after training. We conclude that vergence training can change oculomotor performance. Although C.I. is often associated with abnormal vergence dynamics, there are no typical C.I. vergence dynamics. Unstable monocular preferences may play a role in the aetiology of C.I.

Slanted lateral rectus recession for exotropia with convergence weakness

OBJECTIVE

To evaluate the efficacy of slanted recession of the lateral rectus (LR) muscle for exotropia (XT) with convergence weakness.

DESIGN

Predesigned, nonrandomized, comparative trial.

PARTICIPANTS

Twelve study patients and six control subjects with XT greater at near than at distance by > or =10 prism diopters (PD).

INTERVENTION

Twelve consecutive patients underwent slanted LR recession, and six consecutive control subjects underwent standard LR recession.

MAIN OUTCOME MEASURES

Between-groups comparison of the postoperative ocular alignment at distance and near, and the difference between them, as well as the stereopsis.

RESULTS

Slanted LR recession reduced the XT to <8 PD in all patients at distance and in 11/12 patients at near. Additionally, the mean difference between the distance and near exodeviation was reduced from 14+/-4.5 PD preoperatively to 2.9+/-2.4 PD postoperatively. All patients in the control group demonstrated postoperative deviations of <8 PD at distance, but all had residual exodeviations >8 PD at near. Three of the study patients gained gross stereopsis postoperatively.

CONCLUSIONS

Slanted recession of the LR is superior to standard recession in reducing both distance and near XT and in collapsing the difference between them. This technique may also have a positive impact on gross stereopsis.