The relationship between stereopsis and visual acuity after occlusion therapy for amblyopia

Abstract

Purpose: To investigate the relationship between visual acuity (VA) and stereoacuity after occlusion therapy in patients with various types of amblyopia. Design: Retrospective noncomparative case series. Participants: Sixty-one children with amblyopia caused by anisometropia with no strabismus (26 children), small angle ( 8 prism diopters) or intermittent strabismus (20), or both (15). Methods: All were treated with occlusion therapy. Visual acuity and near stereopsis using the Titmus test (Stereo Optical Inc., Chicago, IL) were measured at each clinic visit. Main Outcome Measure: The change in near stereopsis relative to distance VA after occlusion therapy. Results: Mean age at initiation of therapy was 5.1 years (range 3.5– 8) and mean follow-up 52.3 weeks (range 13–192). Mean duration of occlusion was 36 weeks (range 12–102). After occlusion treatment, mean VA of all children improved from 0.43 to 0.78 (P 0.0001), whereas mean stereoacuity improved from 1167.4 seconds of arc to 101 (P 0.0001). By the last visit, 85.2% (52 of 61) of patients demonstrated at least 2 lines of improvement in VA. There was a significant linear relationship between VA and stereoacuity (P 0.001). The 26 anisometropic patients without strabismus enjoyed improvement in VA and stereopsis (P 0.0001) similar to that of the 35 with small-angle or intermittent strabismus (P 0.0001). Conclusions: When employing occlusion therapy for amblyopia (due to anisometropia, small-angle or intermittent strabismus, or a combination), as VA improves, stereopsis generally also improves. Ophthalmology 2003;110:2088–2092