Regional extent of peripheral suppression in amblyopia

TitleRegional extent of peripheral suppression in amblyopia
Publication TypeJournal Article
Year of Publication2017
AuthorsBabu, R., S. Clavagnier, W. Bobier, B. Thompson, and R. Hess
JournalInvestigative Ophthalmology and Visual Science
Keywordsadult, Amblyopia, anisometropia, Article, Binocular, binocular vision, clinical article, complication, Contrast sensitivity, controlled study, eccentricity, female, human, Humans, interocular suppression, male, middle aged, pathophysiology, perceptive threshold, peripheral suppression, Periphery, Photic Stimulation, photostimulation, physiology, porta test, priority journal, procedures, sensory system parameters, Sensory Thresholds, stereoacuity, Strabismic amblyopia, strabismus, Suppression, Vision, Visual acuity, visual angle, visual field, Visual Fields, visual stimulation

PURPOSE. Previously, we have mapped amblyopic eye suppression within the central 20º of the visual field and observed a gradient of suppression that is strongest in central vision and weakens with increasing eccentricity. In this study, using a large dichoptic display, we extend our novel suppression mapping approach further into the periphery (from 20º–60º) to assess whether suppression continues to decline with eccentricity or plateaus. METHODS. Sixteen participants with amblyopia (10 with strabismus, 6 with anisometropia without strabismus; mean age: 37.9 ± 11 years) and six normal observers (mean age: 28.3 ± 5 years) took part. The visual stimulus (60º diameter), viewed from 57 cm, was composed of four concentric annuli (5º radius) with alternate contrast polarities starting from an eccentricity of 10º. Each annulus was divided into eight sectors subtending 45º of visual angle. Participants adjusted the contrast of a single sector presented to the fellow eye to match the perceived contrast of the remaining stimulus elements that were presented to the amblyopic eye. A matching contrast that was lower in the fellow eye than the amblyopic eye indicated suppression. RESULTS. Patients with strabismus exhibited significantly stronger interocular suppression than controls across all eccentricities (P ¼ 0.01). Patients with anisometropia did not differ from controls (P ¼ 0.58). Suppression varied significantly with eccentricity (P ¼ 0.005) but this effect did not differ between patient groups (P ¼ 0.217). CONCLUSIONS. In amblyopia, suppression is present beyond the central 10º in patients with strabismus. Suppression becomes weaker at greater eccentricities and this may enable peripheral fusion that could be used by binocular treatment methods. © 2017 The Authors.