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J. Lamparter, A. Schulze, A.-C. Schuff, N. Pfeiffer, E. M. Hoffmann; Learning Curve of Flicker Defined Form Perimetry. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5512.
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Flicker defined form perimetry (FDF-perimetry) is a new technique which was designed to investigate early glaucomatous damage by targeting magnocellular retinal ganglion cells similar to FDT-perimetry. Randomly positioned stimuli of black and white dots flicker at high temporal frequency in counterphase. They create the illusion of an edge of a gray circle against a background which can be perceived by the patient. It is the aim of this study to analyze the learning curve of this new technology, and to evaluate possible fatigue effects when examining one eye immediately after the other eye.
150 eyes of 75 healthy subjects aged between 20-80 years were included in this prospective study. The left eye was examined immediately after the right eye with a rest of less than 60 seconds. Every subject was measured three times on three different days. The differences of MD-values were calculated for days 1 and 2 (I= MD2-MD1), days 2 and 3 (II=MD3-MD2), and days 1 and 3 (III=MD3-MD1). To assess the affect of fatigue, differences of MD-values between left and right eyes were calculated. Statistical analysis was performed by means of paired t-tests, 99%-confidence-intervals, and sign tests.
MD was improving significantly between all tests for each, right eyes and left eyes (I; II; III) with mean differences of +0,06 p<0,001 (I); +0,11 p<0,001 (II); +0,18 p<0,001 (III) and 99%-CI-(I) [0.02; 0.11], 99%-CI-(II) [0.07; 0.16], 99-CI-(III) [0.12; 0,23]. Compared to the right eyes, MD of left eyes was significantly smaller when examining the left eye immediately after the right eye (mean difference = -0,57 p<0,001 and 99%-CI [-0,61; -0,52]).
For repeated FDF peimetry there is a significant learning curve between measures 1 and 2, measures 2 and 3, and measures 1 and 3 in right and left eyes. In contrast to other perimetry methods there is a significant fatigue effect which should be considered when examining one eye immediately after the other eye. For good and reliable results on flicker defined form perimetry, at least 3 tests should be performed in an individual. Between the tests of both eyes, a rest should be offered. For a better appraisement it would be interesting to examine both, OHT and glaucoma patients, and to evaluate if there exists a learning curve, too.
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