Abstract
Purpose :
Previous work has established amblyopes experience broad foveal vision deficits including loss of acuity, binocular vision, and stereopsis. We examine differences in peripheral stereoacuity and ocular dominance in subjects with anisometropic amblyopia, strabismus, and normal binocular vision to determine if there are systematic patterns of deficits across the visual field.
Methods :
Stimuli were presented on a LG passive 3D television (57 x 32 deg) and a Tobii EyeX eye tracker was used to enforce fixation compliance. Stereoacuity and ocular dominance were tested at 0, 4 and 8° eccentricities (4 angular locations each). To measure stereoacuity, observers indicated which of three randomly-selected band-pass filtered rings (3 cycles per degree) appeared in front depth. Stereoacuity thresholds were calculated as the disparity at which the subject identified the front-depth ring with 80% accuracy. Ocular dominance was assessed with band-pass filtered optotypes (3 cycles per degree) dichoptically presented with different contrast to each eye. The interocular contrast ratio was adjusted until the subject reported each optotype with equal frequency (Kwon et al, 2015).
Results :
This prospective pilot study recruited 2 subjects with anisometropic amblyopia, 4 with strabismus and 4 controls (age range 20-40 years). Both strabismic and anisometropic subjects showed reduced ocular dominance (a more balanced contrast ratio) at 4° and 8° eccentricities as compared to central vision. Mean difference between peripheral (8°) and central ocular dominance was larger for anisometropic than strabismic subjects (20% ± 14% vs. 10% ± 8% contrast). Normally-sighted individuals had lower disparity thresholds compared with binocularly abnormal subjects at all locations (494.7 vs 1149.6 arcsec). Relative stereoacuity deficit (binocularly abnormal/control) decreased with increasing eccentricity (Pearson’s r= -0.94, p = 0.23).
Conclusions :
There is evidence of decreased relative stereoacuity and binocularity deficits, or reduced ocular dominance, in the periphery in anisometropic amblyopia and strabismus. This difference in peripheral binocular function highlights relatively spared binocular visual function in subjects with compromised central binocularity.
This is a 2020 ARVO Annual Meeting abstract.