Name a common cause of sudden painless monocular vision loss due to optic neuropathy and its distinguishing features.

• A. Anterior ischemic optic neuropathy; sudden vision loss with possible optic disc pallor and vascular risk factors.
• B. Ocular migraine; temporary visual aura.
• C. Retinal detachment; curtain of darkness.
• D. Glaucoma; gradual loss.

Answer: (A)