The identifying characteristics of the monocular syndrome of incipient prechiasmal optic nerve compression are slowly progressive dimming of vision with near normal acuity, poor color perception, positive Marcus Gunn pupillary sign, and normal appearance of the optic disc. Associated visual field defects are subtle and nondescript, but progressive. Even the smallest prechiasmal tumors causing this syndrome can now be detected and defined anatomically with modern neuroradiologic techniques, the most informative of which are serial polytomography of the optic canals and pneumotomography of the prechiasmatic cisterns. Microsurgical resection of the compressive lesion greatly reduces operative trauma and ensures the chance for prompt restoration of vision. Problems in diagnostic and surgical management of patients with incipient optic nerve compression are exemplified in reports of six cases.
Knight CL, Hoyt WF, Wilson CB. Syndrome of Incipient Prechiasmal Optic Nerve CompressionProgress Toward Early Diagnosis and Surgical Management. Arch Ophthalmol. 1972;87(1):1-11. doi:10.1001/archopht.1972.01000020003001