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[Increased threshold for detection of phase differences in pattern-induced color flicker fusion in patients with
1Institut für Zoologie der Johannes Gutenberg Universität, Mainz.
Background:
Pattern-induced flicker-colors are subjective colors produced by rotating disks with black-and-white arcs. Changing the direction of rotation results in a different color. Small variations in the temporal sequence (phase differences) of the black-and-white pattern cause the colors to vary and can be perceived as color differences.
Patients And Methods:
We investigated the thresholds for such phase differences in healthy (n = 11) and in glaucomatous (n = 19) eyes. Acuity and color vision were tested and in patients static visual field perimetry (Octopus G1) was carried out. The disks used for producing the pattern-induced flicker-colors were viewed from a distance of 2 m and had a luminance of 35 cd/m2. The phase difference thresholds were determined using a double staircase procedure.
Results:
In glaucomatous eyes the thresholds were significantly higher (33.9 +/- 4.8 for clockwise rotation) than in normal eyes (18.2 +/- 1.4), p < 0.005 and this was the case for anticlockwise as well as clockwise rotation. The difference between the two groups remained significant (p < 0.025) when the data for glaucomatous eyes was corrected for acuity losses.
Conclusions:
In the glaucomatous eyes the increase in phase difference threshold was correlated with raised visual field MD (r = 0.87 for clockwise rotation). The higher thresholds in glaucomatous eyes point to a loss in blue-yellow-sensitive, parvocellular retinal ganglion cells, which play an important part in the perception of pattern-induced flicker-colors. Pattern-induced flicker-colors are a new method for the clinical investigation of retinal function in the center of the visual field and have the advantage that fixation is unnecessary and the yellow filter properties of the refractive media and the macula are of no importance.