Visual functions in amblyopia as determinants of response to treatment

Longitudinal Evaluation of Accommodation During Treatment for Unilateral Amblyopia

Purpose

Retinal image quality is dependent on accommodative performance. This longitudinal observational study of children with unilateral amblyopia evaluated the accommodative performance of the amblyopic eye during treatment.

Methods

Twenty-six participants with unilateral amblyopia and 10 participants with typical vision aged 3 to 10 years participated. Accommodative response was measured using modified Nott retinoscopy in monocular and binocular viewing conditions for target distances of 50, 33, and 25 cm, at enrollment and each follow-up visit.

Results

Participants with amblyopia accommodated less accurately when viewing with their amblyopic eye in monocular than in binocular conditions. Over the course of amblyopia treatment, accommodative performance improved with amblyopic eye visual acuity (VA) improvement, although this was not consistent across individual participants. A linear mixed model showed that accommodative error worsened with increasing depth of amblyopia for monocular viewing with the amblyopic eye (0.14 diopter [D] per line of acuity loss, P = 0.001), with an interaction between VA and stimulus demand (0.09 D of additional lag per diopter of stimulus, per line of acuity loss, P < 0.001). Participant age, patching duration, length of time in the study, history of strabismus, and stereoacuity were not significant predictors of accommodative performance.

Conclusions

Overall, poor monocular accommodative performance of the amblyopic eye was associated with worse amblyopia and improved simultaneously with VA improvement, although there was variability across the study cohort. Further research is needed to determine the causal relationship between amblyopic eye VA and accommodation and its impact on amblyopia treatment.

Amblyopia in High Accommodative Convergence/Accommodation Ratio Accommodative Esotropia. Influence of Bifocals on Treatment Outcome

PURPOSE

To study the influence of bifocal use on amblyopia treatment outcome in high accommodative convergence/accommodation (AC/A) ratio accommodative esotropia with deviation only at near.

DESIGN

Retrospective comparative case series.

METHODS

Setting: Tertiary referral center.

PATIENTS

Children with high AC/A ratio accommodative esotropia aged 3-8 years old, with deviation only at near with glasses, neutralized with bifocal lenses (follow-up 1 year).

INTERVENTION

Amblyopia was treated with patching. We compared bifocal and single-vision glasses users at 6 months and 1 year, with control of potential confounding variables (multiple regression).

MAIN OUTCOME MEASURES

LogMAR lines of improvement in visual acuity of the amblyopic eye, and improvement in stereoacuity.

RESULTS

Of 78 children, 61 were eligible. All patients wore single-vision glasses for 2 months (baseline visit), 46 of them changed to bifocals. Of 27 initially amblyopic children, 21 remained amblyopic at 2-month baseline (13 of them changed to bifocals). After adjustment for initial deviation, refraction, age, and amblyopia, improvement of visual acuity in the amblyopic eye was larger in the bifocal vs single-vision group at 6 months (mean 2.6 [95% confidence interval (CI): 1.9-2.9] logMAR lines vs mean 1.9 [95% CI: 0.5-2.2] logMAR lines, respectively, P = .01), but not at 1 year (mean 2.7 [95% CI: 2.2-3.1] logMAR lines vs mean 2.3 [95% CI: 1.6-3.1] logMAR lines, respectively, P = .3). Improvement of stereoacuity was not significantly different between the 2 groups.

CONCLUSIONS

Use of bifocals may provide a transient advantage, but improvement in visual acuity and stereopsis is equal with single-vision glasses over time.

Accommodative performance of children with unilateral amblyopia

PURPOSE

The purpose of this study was to compare the accommodative performance of the amblyopic eye of children with unilateral amblyopia to that of their nonamblyopic eye, and also to that of children without amblyopia, during both monocular and binocular viewing.

METHODS

Modified Nott retinoscopy was used to measure accommodative performance of 38 subjects with unilateral amblyopia and 25 subjects with typical vision from 3 to 13 years of age during monocular and binocular viewing at target distances of 50, 33, and 25 cm. The relationship between accommodative demand and interocular difference (IOD) in accommodative error was assessed in each group.

RESULTS

The mean IOD in monocular accommodative error for amblyopic subjects across all three viewing distances was 0.49 diopters (D) (95% confidence interval [CI], ±1.12 D) in the 180° meridian and 0.54 D (95% CI, ±1.27 D) in the 90° meridian, with the amblyopic eye exhibiting greater accommodative errors on average. Interocular difference in monocular accommodative error increased significantly with increasing accommodative demand; 5%, 47%, and 58% of amblyopic subjects had monocular errors in the amblyopic eye that fell outside the upper 95% confidence limit for the better eye of control subjects at viewing distances of 50, 33, and 25 cm, respectively.

CONCLUSIONS

When viewing monocularly, children with unilateral amblyopia had greater mean accommodative errors in their amblyopic eyes than in their nonamblyopic eyes, and when compared with control subjects. This could lead to unintended retinal image defocus during patching therapy for amblyopia.

A 1-Year Review of Amblyopia and Strabismus Research

PURPOSE

This current review highlights some of the literature published in the past year from April 2013 to May 2014.

DESIGN

Literature Review.

METHODS

The present review is based on an extended search for pertinent articles on amblyopia and strabismus published during the specified period.

RESULTS

Many articles are often not very comparable to one another because of a lack of randomized clinical trials with most of the studies being retrospective in nature. There is often disagreement on some terminology. Typically, the definition of binocular vision is rarely related to the tests used for evaluating it.

CONCLUSIONS

The authors conclude that adult strabismus patients seem to gain benefits from corrective surgery not only for their ocular misalignment, but also for social anxiety levels that may be associated with improvements in their quality of life and disability levels.