The differential diagnosis of retinal disease from optic nerve disease.

Patients complaining of reduced acuity in the absence of a clearcut diagnosis present a challenge to the eye care practitioner. It is important to differentiate retinal disease from optic nerve disease as the etiology of the decrease in vision. This differentiation can have significant ramifications and must be determined for patient welfare and management. Several procedures may be used in making the differential diagnosis of macular or retinal from optic nerve disease. Some of these procedures are easy to perform and include Amsler grid, color vision testing, pupillary reflexes, light-brightness comparison, and macular dazzle. Other procedures require a greater degree of sophistication and include fluorescein angiography, the Visual Evoked Potential (VEP) and simultaneous VEPs and ERGs (Electroretinograms). The clinician should be aware of all of these procedures and how each may be useful in this differential diagnosis.