SEP 26, 2016
Optic nerve pallor can be a false localizing sign because not all cases of optic nerve pallor are due to primary optic nerve pathology. Retinal dystrophies (in particular cone dystrophies), retinal degenerations (ie, retinitis pigmentosa), and retinal artery occlusions can all result in secondary optic nerve pallor.
When interpreting an OCT, review not only the retinal nerve fiber layer, but the macular thickness maps and the individual cross-sectional images. Certain disease processes have a predilection for particular layers of the retina, eg, retinal artery occlusion (RAO) causes thinning of the inner layers whereas acute macular neuroretinopathy (AMNR) affects the outer layers. Macular OCT findings can also aid in differentiating postacute RAO from nonacute optic neuropathies. Macular thinning is more profound in eyes with RAO than in eyes with nonarteritic anterior ischemic optic neuropathy (NAION).