Monocular vernier acuity in normally binocular, monocular, and amblyopic subjects.

Previous experiments that have compared monocular vernier acuity in amblyopic, monocularly blind, and normal binocular subjects have been confined to the center of the retina. Based on brain changes that accompany the early disruption of form vision in one eye, monocularly blind subjects (that is, those who have completely lost the ability to process form vision in one eye) and amblyopic subjects are expected to have better vernier acuity in their normally functioning eye than subjects with normal binocular vision. Results from such studies have been ambiguous. This experiment was set up to study monocular vernier acuity in the central and peripheral retina of the three groups of subjects mentioned above. The results show that, at the center, monocularly blind subjects have the best vernier acuity followed by the amblyopic subjects and, finally, the normal binocular subjects have the worst acuity. In the peripheral retina, no significant differences were found between the three groups. A possible explanation has been provided for this finding.