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Matt J Chapin, Divya Narayanan, John David Rodriguez, Garrick Wallstrom, Donna Welch, Mark B Abelson; Variable Contrast Flicker Tests in Early Dry Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1211. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Flickering stimuli have potential to detect underlying visual dysfunction of the retina. The goal of the current study was to test a series of variable contrast flicker (VCF) stimuli in early dry AMD subjects and age-matched normals.
Twenty seven subjects with early dry AMD (mean age: 74.8±6.5 years) and thirty four normal subjects (73.9±5.3 years) were included in the study. The VCF stimuli were presented on a computer monitor. The stimuli comprised of a series (6 combinations) of flashing lights presented at three temporal frequencies; low (<10Hz), mid (10 to 20Hz) and high (>20Hz) and two background luminance levels in the upper mesopic range. Each stimulus varied in contrast with the background and the contrast at which a subject can no longer perceive the stimulus for a given combination was identified as the threshold. The contrast threshold can range from 0 to 1, with 0 being best possible response and 1 being worst possible response.
Overall, all combinations of the VCF test showed that contrast thresholds were worse in the AMD group than normals. The mean VCF was significantly worse in the early AMD group when compared to the normal group (0.26 ± 0.02 in AMD vs 0.19 ± 0.02 in normals, p= 0.007). The VCF total sum showed a sensitivity of 74% with 80% specificity. There was no significant difference in the ETDRS VA between the early AMD (0.06±0.02 logMAR) and normal group (0.04±0.02 logMAR) (p=0.28).
Our variable contrast flicker test was able to detect significant visual dysfunction in early AMD group compared to age-matched normal controls. The VCF test shows promise as a potential surrogate endpoint in early AMD clinical trials.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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