Purchase this article with an account.
M Belkin, D Zur, L Liu, S Ullman; New Functional Assessment Test for AMD based on the Filling-in of the Retinal scotomas . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3912.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To find a visual field defect assessment that can faithfully reflect Age-related Macular Degeneration (AMD) patient's perceived disability in daily activities due to central scotomas. Methods: According to four years ongoing research on the AMD patient's perception we hypothesize that a more realistic measurement of visual field defects can be obtained by using stimuli that facilitate, not inhibit, perceptual filling-in. To test the hypothesis, we presented regular and irregular dot arrays and line gratings to four AMD patients and analyzed their perception. The density of the eight regular dot arrays varied from 0.13 to 1.16 dots/degree, and the two irregular dot arrays had fixed average density of 0.87 dots/degree with maximum irregularity of 26.5% and 79.5% of the inter-dot average distance. The seven line gratings had spatial frequency varied from 0.26 to 6.28 cycles/degree. The patients were asked to rate the uniformity of the perceived stimuli in numbers between zero and five, and to specify the number of the missing dots, and the type of the perceived non-uniformity in terms of continuity, straightness, contrast, and blur. Results: For the linear patterns, the perceptual uniformity in the scotoma region increased with the gratings frequency up to 6.28 cycles/degree. For the two-dimensional dot patterns, perceived uniformity increased with the density and regularity of the arrays. All the patients reported some missing dots at the low densities. Only one patient with the most severe damage, worse than 20/300, reported missing dots at the high densities of the regular arrays, and discontinuity at the high frequencies of the gratings. Conclusion: We found high correlation between the pattern's density and frequency, and its perceived uniformity. We believe that quantified uniformity perception, like the measurement of the number of the missing dots, can be converted to an assessment of the extent of perceived field defects, and to different typical functions for different level of defects. Unlike traditional perimetry outcomes, such assessment has taken perceptual filling-in into consideration, due to the properties of the stimuli, thus it is more realistic assessment of the patient's visual impairment in the daily life.
This PDF is available to Subscribers Only