Reduced Mesopic and Photopic Foveal Contrast Sensitivity in Glaucoma

OBJECTIVE: To demonstrate differences in foveal contrast sensitivity (CS) between glaucomatous and nonglaucomatous eyes using a simple, rapid computerized test. METHODS: This study included consecutive patients with glaucoma (35 eyes) and age-matched control participants (23 eyes) with visual acuity of 20/30 or better. Patients with any other ocular disease, including cataract, were excluded. All participants underwent a comprehensive ocular examination, perimetry, and CS. Contrast sensitivity was examined by means of 2 computerized psychophysical tests. The transient method included the presentation of a target in a temporal, 2-alternative, forced-choice procedure, and the static method involved 4 forced-choice procedures. The targets were Gabor patches with spatial frequencies of 1.5 to 9.0 cycles per degree. The tests were conducted under photopic and mesopic conditions. RESULTS: Significantly lower foveal CS was found in glaucomatous eyes under photopic and mesopic conditions for all spatial frequencies (P < .01). The transient and static methods yielded similar results and were significantly correlated (P < .001). All transient photopic and mesopic CSs were significantly correlated with cup to disc ratio (P < .05). The static photopic spatial frequency of 6 cycles per degree was significantly correlated with the severity of the glaucomatous damage. CONCLUSIONS: The results indicate that foveal CS is impaired in glaucoma despite good visual acuity, suggesting that central visual function damage occurs in glaucoma. The similarity between the 2 methods of testing implies that the static method, being the shorter and easier one, may be used in future research. Further research is necessary to establish a CS testing role in the screening and monitoring of glaucoma.