We examined two groups of patients with primary open-angle glaucoma with distinctly different patterns of early visual field loss using two visual field indices: mean defect and loss variance. Patients were selected on the basis of visual field criteria only. Eight patients were selected for diffuse depression of the differential light sensitivity without localized scotomas (mean defect > 3.0 decibels, loss variance < 10.0 decibels2). Seven patients were selected for localized scotomas without diffuse depression of the differential light sensitivity (mean defect ≤ 3.0 decibels, loss variance ≥ 20.0 decibels2). Patients with diffuse depression manifested intraocular pressures that were higher (mean peak pressure ± S.E.M., 27.6 ± 1.2 mm Hg) than those with localized defects (22.4 ± 1.4 mm Hg). The optic disk rim area of the localized loss group (mean ± S.E.M., 1.02 ± 0.15 mm2) was significantly smaller (P < .05) than the disk rim area of the diffuse loss group (1.33 ± 0.07 mm2). This difference was largely because of thinner temporal disk rims in the localized loss group. Different patterns of visual field loss may be caused by different mechanisms of glaucomatous optic nerve damage.
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