Cupping of the optic disc with compressive lesions of the anterior visual pathway.

Cupping of the optic nerve, classically a sign of glaucoma, was demonstrated in 16 patients with lesions compressing the anterior visual pathway. Color contrast determinations of the cup/disc ratio demonstrated a ratio greater than 0.49 in 31 eyes. Further evaluation by stereobiomicroscopy showed cavernous degeneration by contour changes in 25 of the optic nerves. None of the patients had intraocular pressures greater than 22, and seven had normal tonography. Visual fields demonstrated bitemporal field defects in most patients and none were typical of glaucoma. Snellen acuity loss, out of proportion to the extent of optic disc cupping was found in 12 patients. This study indicates that diseases other than glaucoma can cause significant cupping of the optic nerves. Detailed evaluation of the disc changes and the visual fields will prevent confusion between compressive lesions of the optic nerves or chiasm and glaucoma.