Abstract
Abstract: :
Purpose: To determine the relationship between dynamic visual field perimetry (a test of how well the visual field is scanned) and a self–report assessment of everyday function (VA–28) in people with restricted visual fields. Methods: Dynamic Visual Field Perimetry and SLO Macular Perimetry were performed binocularly and monocularly, respectively, in 16 people with visual fields 20 degrees or less due to RP (retinitis pigmentosa). Dynamic Visual Fields were determined by randomly presenting targets in a radial pattern (targets at 4, 8, and 12 degrees on 8 radial lines) while subjects scanned the visual field to find the targets. The targets were left on until the subject indicated the direction of the target (relative to the center of the visual field). Subjects also rated (four levels) their abilities, independence, and satisfaction of 28 everyday functional tasks using the VA–28. The VA–28 is a reliable and valid self–report questionnaire used for the evaluation of vision rehabilitation services for people who are legally blind. Visual acuity was measured with the ETDRS Chart and contrast sensitivity was measured with the Peli–Robson chart. Results: Subjects had median visual acuity of 0.48 logMAR (range: –0.24 to 0.88) and median contrast sensitivity of 0.95 logcontrast (range: 0.15 to 1.75). All subjects had some visual deficits in the central 20 degrees as well as restricted visual field loss. Dynamic visual field times ranged from 0.60 to 8.2 seconds (95% of normally sighted subjects have times of 1.0 second or less). Subject’s self–reported ratings of abilities, independence and satisfaction of the 28 everyday functional tasks were not significantly related (contingency table analysis). Ordinal logistic regression analysis found that the VA–28 ability and independence rating responses are significantly related to the dynamic visual field times (ChiSqaure; p > 0.05) but not to visual acuity, contrast sensitivity, or central visual field loss. Satisfaction of everyday functional tasks was not related to any measure. The dynamic visual field pattern locations with longer–than–normal times (1.0 second) were not comparable to the extent of the central visual field within the restricted visual field. Further analysis of the 28 individual everyday functional tasks will be presented. Conclusions: Ability and independence of doing everyday functional tasks are related to the ability to scan the visual field quickly and efficiently. Dynamic Visual Fields may be a better outcome measure of the effect of visual field loss on everyday function than standard flash perimetry, visual acuity, or contrast sensitivity.
Keywords: perimetry • visual search • visual fields