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Michelle Liu, Jason C Park, J Jason McAnany; Clinically-applicable paradigms and normative data for classic psychophysical measures. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4612.
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© ARVO (1962-2015); The Authors (2016-present)
Although classic psychophysical measures of spatial summation (SS), temporal summation (TS), and threshold vs adapting illuminance (TvI) provide important information about the health and function of the visual system, these measures are not readily performed with clinical instruments. This study sought to expand the translational potential of these measures by developing and applying SS, TS, and TvI protocols using a commercially available perimeter.
Perimetry was performed with an Octopus 900 (Haag-Streit) in 9 visually-normal subjects (age 23 to 42 years). Threshold was measured at 15 locations on the horizontal meridian from 60o temporal to 45o nasal. These locations were grouped into foveal, parafoveal, perifoveal, and peripheral areas. Three protocols were performed: 1) SS: target duration was 100 ms and size varied from 0.1o to 1.7o (Goldmann sizes I to V). 2) TS: target size was 0.43o and duration varied from 12 to 800 ms. 3) TvI: target duration was 100 ms, size was 0.43o, and adaptation level varied from 0 to 50 cd/m2. SS and TS measures were performed with achromatic targets on a 50 cd/m2 adapting field, whereas TvI measures were performed with short wavelength targets after 30 min of dark adaptation. Critical values for TS and SS were derived from piecewise linear fits. TvI data were fit with conventional functions to derive absolute threshold, slope, and eigengrau.
The mean critical area for SS, beyond which threshold was independent of size, ranged from 0.4 deg2 at the fovea to 0.7 deg2 in the periphery. Repeated measures ANOVA indicated significant differences among field locations (p = 0.04). The mean critical duration for TS, beyond which threshold was independent of duration, ranged from 64 ms at the fovea to 91 ms in the periphery; differences among field location were statistically significant (p = 0.04). Dark-adapted absolute threshold measured from the TvI curves decreased with eccentricity (p = 0.003). The slope of the TvI functions increased with eccentricity (p < 0.001), whereas eigengrau was independent of location (p = 0.64).
We provide approaches to perform and interpret classic psychophysical measures with a commercially available perimeter. Normal ranges for young healthy subjects were obtained that will be essential for future clinical studies of juvenile x-linked retinoschisis and other retinal disorders.
This is a 2020 ARVO Annual Meeting abstract.
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