Diffuse loss of sensitivity in early glaucoma

PURPOSE. TO establish whether there is significant diffuse loss of sensitiv ity in a population of patients with early glaucoma. METHODS. The differential light sensitivities at the 10 most sensitive loca tions from within the central 24 degrees of program 30-2 of the Humphrey Fi eld Analyzer(Humphrey Instruments, San Leandro, CA) were compared in 38 pai rs of age-matched subjects, one of each pair with early primary open-angle glaucoma (POAG) and the other with normal eyes. All subjects had had experi ence with automated perimetry and had clear media, visual acuity of 20/25 o r better, and one or fewer false-positive or false-negative responses to ca tch trials. RESULTS. The mean difference in age between the subjects with glaucoma and normal subjects was 29 days (P = 0.44, maximum 1.42 years). The mean paired difference in pupil size was 0.16 nun (P = 0.26), and visual acuity was hi gher in the glaucoma-affected subjects (P = 0.044). The 10 highest sensitiv ity measurements in the POAG-affected subjects were found to be lower by a median of between 1.0 and 2.0 dB than those in the normal pair members (0.0 001 < P < 0.012, sign test). In 60% of the pairs the sensitivity at the sev enth most sensitive location was 2 dB or more lower in the POAG-affected ey es. CONCLUSIONS. Early glaucomatous visual field loss frequently involves a dif fuse component that includes the 10 most sensitive locations. These finding s suggest that purely localized visual field loss in glaucoma is rare. Thes e observations could not be explained by factors of pupil size and media op acity.