When acute or subacute blindness occurs in adult life, meningeal carcinomatosis should be included in the differential diagnosis, even in the absence of other symptoms. Blindness occurs in about one third of cases of meningeal carcinomatosis. Spinal fluid filtration (Millipore) examination and spinal fluid glucose are the most useful diagnostic tests in meningeal carcinomatosis, but results of both may be normal. Meningeal tumor-cuffing around the optic nerves, chronic papilledema, and infiltration of optic nerve parenchyma by tumor cells are the three likeliest causes for blindness in meningeal carcinomatosis, either acting alone or in combination. Some cases of meningeal carcinomatosis, however, are not adequately explained by any of these mechanisms.
Altrocchi PA, Reinhardt PH, Eckman PB. Blindness and Meningeal Carcinomatosis. Arch Ophthalmol. 1972;88(5):508-512. doi:10.1001/archopht.1972.01000030510007