Subnormal binocular vision with special reference to peripheral fusion

Abstract

An analysis has been made of the state of binocular vision of 200 consecutive and unselected patients with convergent squint treated during the period 1950/54 by operation and/or orthoptic treatment and occlusion. The patients were divided into three groups: (1) Those with binocular single vision. (2a) Those with subnormal binocular vision. (2b) Those with grossly defective binocular vision. To discover whether visual judgement was better in patients with " subnormal binocular vision " than in those with a gross defect of binocular vision, twenty patients from each group were examined on the Livingston rotating depth perception apparatus. All the patients in Groups 2a and 2b gave a poor performance as compared with those in Group 1, and, if anything, the performance of those in Group 2a was slightly worse than that of those in Group 2b. A series of the patients with subnormal binocular vision was examined to determine the presence of peripheral fusion. Twenty patients with subnormal binocular vision (and fifty controls with binocular single vision) were examined by the screen test, and thirty patients with subnormal binocular vision (and twenty controls with binocular single vision) were examined by the stereoscopic test. The results are varied and inconclusive owing to the subjective nature of the tests, but peripheral fusion with a varying intensity of peripheral suppression could be demonstrated in all cases in which normal retinal correspondence was present.