CLINICAL MEASUREMENT OF ECCENTRIC CHROMATIC CONTRAST SENSITIVITY IN PATIENTS WITH GLAUCOMA

William Swanson

Abstract

PURPOSE. We have previously used measurement of eccentric chromatic contrast sensitivity in patients with glaucoma to documented modest (6-9 dB) improvements in visual function following glaucoma surgery (Fellman et al., American Academy of Ophthalmology, 1999). However, the size and complexity of the xenon-arc-based apparatus made this system impractical for routine clinical use. Therefore we have developed a small, inexpensive clinical testing station for measuring eccentric chromatic contrast sensitivity. METHOD. An iMac computer, mounted on an examining chair, was calibrated and programmed to produce stimuli modulated from equal-energy white along three cardinal directions in color space: equiluminant red-green and tritan axes, and the luminance axis. Stimuli were 500 msec pulses presented at five locations: at the fovea and at 12° eccentricity along the four diagonal meridia. The stimuli were squares, 0.6° on a side in the fovea and 3° on a side at the eccentric locations. Subjects were tested twice, in sessions one week apart, to assess test-retest variability.

RESULTS. Test-retest variability in patients and normal subjects was similar to that obtained with the xenon-arc-based system, with 99% confidence limits for test-retest variability less than 6 dB. Patient acceptance was good, with testing time typically less than 5 minutes. Blind-spot testing showed that the stimulus configuration encouraged proper fixation. Decrease in stimulus duration fro 500 msec to 50 msec had little effect on luminance sensitivity and a dramatic effect on chromatic sensitivity, showing that chromatic channels were successfully isolated.

CONCLUSIONS. Low test-retest variability makes this system suitable for detecting modest changes function in response to treatment for glaucoma

Details

Year: 2001

Program Number: Poster 50

Author Affiliation: State University of New York

Co-Authors: Mitchell Dul, Fei Pan, Ngoc Ly

Co-Author Affiliation: State University of New York, State University of New York, State University of New York

Room: Exhibit Hall C