Inverse occlusion, a binocularly motivated treatment for amblyopia

Abstract

Purpose : Recent laboratory finding suggest that short-term patching the amblyopic eye (i.e., inverse occlusion) results in a larger and more sustained improvement in the binocular balance compared with normal controls. In this study, we investigate the cumulative effects of the short-term inverse occlusion in adults and old children with amblyopia.

Methods : A prospective cohort study of 18 amblyopes (10-35 years old; 3 with strabismus) who have been subjected to 2 hours/day of inverse occlusion for 2 months. Patients who required refractive correction or whose refractive correction needed updating were given a 2-month period of refractive adaptation. The primary outcome measure was the binocular balance which was measured using a phase combination task, the secondary outcome measures were the best corrected visual acuity which was measured with a Tumbling E acuity chart and convert to logMAR units and the stereo acuity which was measured with the Random-dot preschool stereotest.

Results : The averaged binocular gain was 0.11 in terms of the effective contrast ratio (z = -2.344, p= 0.019, 2-tailed Related samples Wilcoxon Signed Ranks Test). The average acuity gain was 0.13 logMAR equivalent (t(17) = 4.76, p< 0.001, 2-tailed paired samples t-test). The averaged stereo acuity gain was 339 arc seconds (z = -2.533, p= 0.011).

Conclusions : Based on more recent research concerning adult ocular dominance plasticity, we conclude that inverse occlusion in adults and old children with amblyopia does produce long term gains to binocular balance and that acuity and stereopsis can improve in some subjects.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.