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Connie Slocum, Keith Jeffrey Lane, John David Rodriguez, Aron Shapiro, Mark Abelson, David Hollander; Use of a Computer-based Critical Flicker Fusion Test Discriminates between Young, Old, and Dry AMD Patients. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2347.
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We have developed a simplified computer-based critical flicker fusion (CFF) test to rapidly assess visual function in a patient population for implementation in clinical trials. The test utilizes the PsychoPy toolkit, a software library written in the Python language, which is specifically designed for use in visual psychophysics. The aim of this study was to validate the computer-based CFF test by comparing differences in CFF scores between younger and older normal subjects and subjects with dry AMD.
This study enrolled 23 normal subjects with a mean (SD) age of 44.7 (9) years, 17 older normal subjects with a mean (SD) age of 74.5 (4) years, and 9 subjects with dry AMD with a mean (SD) age of 77.8 (6.8) years. Dry AMD was defined by signs of pigmentary changes, mottling and/or the presence of some drusen, and a potential acuity measurement (PAM) between 20/30 and 20/80. After a 45-minute dark adaptation period, CFF was measured twice in each eye, 5 minutes apart, with stimulus presented using a staircase design with test frequencies set at 20, 24, 30, 40 and 60 Hz. The stimulus used a single circular blob (Goldmann size 5) presented centrally.
Older subjects had reduced CFF relative to younger subjects with 42.9% of eyes in younger subjects perceiving flicker frequencies greater than 30 Hz compared 21.2% of eyes in older subjects. CFF scores for dry AMD subjects showed a reduction in CFF relative to older normal subjects, with 31% of dry AMD subjects having a CFF threshold of 24 Hz relative to 6% for older normal subjects.
A computer-based CFF test may be a valuable tool to discriminate patient populations and may be readily employed for multi-centered trials.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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