Standard Amblyopia Therapy in Adults with Longstanding Amblyopia Improves Visual Acuity and Contrast Sensitivity

Abstract

Purpose

Perceptual learning or dichoptic training may result in improved acuity in adult amblyopes. However, for amblyopic children (<18 years), most clinicians recommend standard part-time patching. The purpose of this study was to determine if standard amblyopia therapy results in an enhancement in vision in the amblyopic eye of adults.

Patients and Methods

Fifteen amblyopes (20/30 or worse) were recruited and nine (age (SD) 32.9 (16.31)) with anisometropia or anisometropia and strabismus (ie, combined mechanism amblyopia) completed the study. Previous therapy did not exclude subjects. The subjects received a comprehensive eye exam and wore their best correction for at least four weeks prior to baseline testing. The non-amblyopic eye was patched for 2 hours per day (Amblyopia iNET training for 30 minutes and near/distance activities for 1.5 hours). The subjects had a baseline amblyopia evaluation followed by one visit per week for 12 weeks. At 12 weeks, the treatment was tapered off over one month and the subjects had a final amblyopia evaluation at 24 weeks. Contrast sensitivity was measured at baseline and 12 weeks with the Quick CSF system.

Results

The subjects had a significant improvement in visual acuity across the weeks (p < 0.001). At baseline, weeks 12 and 24, the average logMAR acuities (SE) were 0.55 (0.09), 0.41 (0.08), and 0.38 (0.09), respectively. Weeks 4 to 24 were significantly different (p < 0.001) from baseline. The average acuity improvement over the 24 weeks was 1.7 logMAR lines. There was a significant increase in the area under the log contrast sensitivity function (p = 0.002) and its estimated acuity (p = 0.036) from baseline to 12 weeks.

Conclusion

Standard amblyopia treatment can result in an improvement in visual acuity and contrast sensitivity in adults with longstanding anisometropic or combined mechanism amblyopia even if they had prior therapy.

Keywords:

• amblyopia
• anisometropia
• strabismus
• contrast sensitivity
• visual acuity

Abbreviations

A, anisometropia; ANOVA, analysis of variance; AULCSF, area under the log of the contrast sensitivity function; C, constant; cpd, cycles per degree; CSF, contrast sensitivity function; E-ETDRS, electronic-early treatment diabetic retinopathy study visual acuity tester; ET, esotropia; XT, exotropia; HyperT, hypertropia; I, intermittent; logMAR, Logarithm of the Minimum Angle of Resolution; S, strabismus; SD, standard deviation; SE, standard error.

Data Sharing Statement

The data for visual acuity and contrast sensitivity are in Table 2. The stereopsis data are in Table 3.

Statement of Ethics

Research was conducted ethically in accordance with the Declaration of Helsinki. For better efficiency, the study protocol was reviewed and approved by a commercial IRB company externally from the University (Sperling Institutional Review Board, Atlanta, Georgia). Written informed consent was obtained from all participants in the study.

Acknowledgments

The authors thank Apoorva Karsolia for collecting some of the data and Loc Nguyen, PhD (California State University) for the statistical analysis. This paper was presented at the Association for Research in Vision and Ophthalmology as an abstract presentation with preliminary findings. The poster’s abstract was published in “Poster Abstracts” in Investigative Ophthalmology & Visual Science July 2018, Vol.59, 4112.

Author Contributions

All authors met the IMCJE authorship guidelines for inclusion. All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

Ursula Staubli is a prior employee and Yong-Xin Li is a current employee of AbbVie. Inc. (formerly Allergan, Inc.). Ursula Staubli is currently affiliated with Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, USA. The authors have no other conflict of interest in this work.

Additional information

Funding

This project was partially funded by Allergan (prior to acquisition by AbbVie). They had no role in study design or manuscript development.