Ophthalmoscopic observation of the retinal nerve fiber layer.

Alterations of the retinal nerve fiber layer occur as a result of diseases affecting the anterior visual pathway. Optimal viewing conditions, familiarity with the appearance of the normal nerve fiber layer, precise focus, and a high index of suspicion are necessary for the ophthalmoscopic observation of pathologic alteration in the nerve fiber layer. The observer must learn to differentiate pseudodefects (reflexes) from true defects (areas of nerve fiber layer atrophy). Nerve fiber layer changes appear ophthalmoscopically as generalized attrition, slit defects, sector defects (all types of atrophic change), or changes in the appearance of the nerve fiber layer itself. These alterations, which occur in numerous conditions including congenital hemianopia, ocular hypertension and glaucoma, multiple sclerosis, acute Leber optic neuropathy, trauma, severe hypertension, congenital and heredity optic atrophy, toxic amblyopia, papilledema, retinochoroiditis, and following photocoagulation, may be of critical diagnostic importance.