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.