Fundoscopy of the retinal nerve fiber layer in neurosurgical practice.

Abstract

The retinal nerve fiber layer surrounding the optic discs provides a unique clinical opportunity to view directly pathologic changes in the neural components of a major sensory pathway in the brain. Minute changes in this neural tissue are best seen in bright red-free light of a direct ophthalmoscope. This report, stressing the neurosurgical significance of peripapillary retinal signs, illustrates and discusses 1) how incipient papilledema obliterates the normally glistening highlights and striations of the nerve fiber layer before any recognizable change is seen in the optic disc, 2) how focal axon degeneration from acute and insidious forms of optic neuropathy causes multiple slit-like thinnings in the arcuate nerve fibers before any recognizable signs of pallor or functional change occurs in the optic nerve, 3) how atrophy, direct or transsynaptic, of an optic tract causes diagnostic homonymous patterns of axon loss in the peripapillary nerve fiber layer and optic disc of the two eyes, and 4) how recognition of fundoscopic signs of hemiretinal and optic hypoplasia allows the neurosurgeon to differentiate the bitemporal or homonymous hemianopias of developmental origin from the acquired effects of brain tumor.