Abstract
Abstract: :
Purpose: "Filling-in" is a common physiological effect that has important clinical implications in conditions of visual field loss such as glaucoma. Our aim was to look at the speed with which different parts of the visual field fill-in, in comparison to contrast detection sensitivity. Methods: A computer-generated artificial scotoma spot (0.5° diameter) was projected onto different locations of the visual fields of five subjects under monocular viewing. The time taken for the spot to disappear was recorded when viewing a higher contrast spot at 5°, 10° and 20° (peripheral field) and a lower contrast spot at 1.25°, 2.5° and 3.75° (central field) in the temporal, nasal, upper and lower visual fields. The subjects also fixated the spot directly (central fixation). The trials were repeated 10 times. Detection threshold was measured at the same locations by projecting a 0.5° spot of varying contrast, using a technique similar to automated perimetry. Results: Vertical visual fields filled-in significantly faster in comparison to horizontal fields for both central and peripheral paradigms (P<0.05); similarly, detection thresholds were lower in vertical fields. All subjects were able to fill-in a low contrast spot if fixating centrally for a prolonged period. Conclusions: Filling-in occurs faster in the vertical visual field than the horizontal visual field. The vertical visual field also has a lower contrast detection sensitivity compared to horizontal fields. Filling-in can be elicited in any part of the visual field provided a spot of sufficiently low contrast is used. This may have clinical implications in the detection of glaucoma.
Keywords: temporal vision • visual fields