Peripheral color contrast. A new screening test for preglaucomatous visual loss.
A new test of peripheral color contrast is described. A high-definition color monitor driven by a personal computer with a graphics interface card displays an annulus subtending 25 degrees at the eye. The color contrast between the annulus and the background can be varied. Forty-five degrees of the annulus is randomly removed in one of four quadrants. Patients are asked to identify the position of the gap while fixating a central spot. The minimum color contrast between annulus and background at which the identification is possible is between 13-16% for the protan, deuteran, and tritan axis in normal subjects. This threshold value changes little with age, refractive error, or pupillary aperture, and test-retest variability is low. Testing one eye takes only 1-2 min. The test was applied to ocular-hypertensive and glaucomatous patients. All patients with glaucoma had thresholds greater than two standard deviations (SD) above the normal mean. In addition, 97% of glaucoma patients had thresholds greater than four SDs, and 95% had thresholds more than five SDs above the normal mean. Most patients with ocular hypertension and clinical signs indicating a low or medium risk of conversion to glaucoma had thresholds under the upper limit of normal. High-risk patients with ocular hypertension fell into two groups. One approximated to normal; the other had elevated thresholds, which in many cases were more than four SDs above the normal mean. The epidemiologic consequences of this test are discussed.
Yu
T C
TC
Department of Clinical Ophthalmology, University of London, United Kingdom.
Falcao-Reis
F
F
Spileers
W
W
Arden
G B
GB
D000328:Adult; D000368:Aged; D003119:Color Perception Tests; D015350:Contrast Sensitivity; D005260:Female; D005901:Glaucoma / Q000517:prevention & control*; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000517:prevention & control*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds; D015351:Vision Screening / Q000379:methods*; D014794:Visual Fields