The combination of vision loss, an RAPD, and optic atrophy is nonspecific and might represent the chronic phase of any of the optic neuropathies described in this chapter. When historical features and clinical signs do not suggest a specific cause, baseline studies of optic nerve function and a screening workup for treatable causes are usually undertaken. The level of optic nerve function is established by visual acuity determination, color vision testing, and quantitative perimetry testing. Fundus photography, preferably in stereoscopic views, can be used to document the degree and pattern of atrophy, helping the clinician detect subtle changes in contour over time. RNFL thickness can be monitored using OCT.
Neuroimaging, preferably MRI of the brain and orbits with use of gadolinium contrast and fat suppression, is warranted in any case of optic atrophy without a clear cause. In the appropriate clinical or historical setting, the clinician should pursue laboratory evaluation. Screening for syphilis, vitamin B12 deficiency, folate deficiency, vasculitis, sarcoidosis, and heavy-metal toxicity should be performed for patients without a history or examination finding suggestive of a specific disease. Observation remains reasonable for patients with negative results from testing. However, if the condition worsens or new findings develop, reassessment of the initial testing or additional testing becomes necessary.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.