Microcysts in the inner nuclear layer, a nonspecific SD-OCT sign of cystoid macular edema

Recently, many authors have propagated the notion that a specific form of "microcystic macular edema" occurs in patients with optic neuritis and optic atrophy of various etiology and is due to retrograde synaptic degeneration. The finding is isolated to the inner nuclear layer on spectral-domain optical coherence tomography in most cases, and is present in a parafoveal, circumferential, and central macular distribution. This perspective critically reviews the evidence and suggests that inner nuclear layer cystoid changes are an early and nonspecific indicator of typical cystoid macular edema of any cause, and that the finding is likely not a distinct entity.