Comparison of the effect of an untreated and successfully treated unilateral macular hole on sensory and motor binocular function

Abstract

Abstract: : Purpose: To study the effect of a unilateral macular hole on stereopsis before and after successful surgical treatment. Methods: Stereopsis was measured using the Titmus test, which utilizes contours, and the TNO random dot stereotest in 15 patients before and two to seven months after successful surgery for a unilateral macular hole (as defined by anatomical closure and improved acuity). Motor fusion was assessed by orthoptic methods. Results: In the presence of an untreated macular hole, stereopsis was reduced to a median of 3000 seconds of arc as measured by the Titmus stereotest and 1700 seconds of arc using the TNO stereotest. Following successful surgical closure, best corrected Snellen acuity improved from a median of 6/60 to 6/18 in the affected eye of this group of patients. Stereoacuity measured by the Titmus stereotest improved to a median of 800 seconds of arc (P=0.016; Wilcoxon rank–sum test). Median stereoacuity measured by the TNO stereotest was unchanged. Motor fusion range was significantly reduced at both 1/3 and 6 metres in the presence of a macular hole, with only limited improvement after surgery. Most patients were not subjectively aware of a problem with depth perception before surgery or of improvement afterwards. Conclusions: In the presence of a macular hole, the size and nature of the stimulus used to measure stereopsis greatly affect the results obtained and indicate that stereopsis mediated by foveal and extra–foveal areas are tested differentially by different stereotests. The stimuli used in the TNO stereotest project onto retinal areas well outside the macular hole and it is likely that abnormal motor fusion plays a part in the reduction in stereoacuity when measured by this test.

Keywords: binocular vision/stereopsis • macular holes