Most ischemic optic neuropathies are attributed to interference of blood flow originating within the posterior ciliary circulation. In patients with the most common type of ischemic optic neuropathy, nonarteritic anterior ischemic optic neuropathy (NAION), the microvascular ischemia predominantly affects the intraocular portion of the optic nerve. NAION most commonly occurs in eyes with small, "crowded" optic disks and usually does not result in optic disk excavation. We report a patient who presented with NAION and subsequently developed optic disc excavation typical of glaucomatous optic neuropathy.