Visual disturbance in patients with melanocytoma of the optic disk. Visual disturbance in 11 patients with melanocytoma of the optic disk was analyzed. Goldmann visual field examination showed enlargement of Mariotte's blind spot in 7 of 10 patients (70%) and visual field defect or depression in 7 patients (70%). In 6 of the 7 patients with visual field defect of depression (86%), the portion of visual field damage corresponded with the location of the tumor and retinal nerve fiber bundle defect. In 1 patient, sudden loss of visual acuity occurred, presumably due to anterior ischemic optic neuropathy induced by melanocytoma. 