Diseases causing sudden uni- or bilateral visual disturbance

1. Big picture

Sudden visual disturbance is a neurological and ophthalmological emergency until proven otherwise. In the exam, the first task is not to list every eye disease, but to answer three questions:

1. Is it monocular or binocular?

   • Monocular visual loss usually localizes anterior to the optic chiasm: eye, retina, optic nerve, ophthalmic artery, internal carotid artery.

   • Binocular visual field loss usually localizes behind the chiasm: optic tract, optic radiation, occipital cortex.

2. Is it transient or persistent?

   • Seconds to minutes, “curtain descending” → think amaurosis fugax / retinal transient ischemic attack.

   • Persistent sudden painless monocular blindness → think central retinal artery occlusion, central retinal vein occlusion, ischemic optic neuropathy, retinal detachment.

   • Hours to days, painful eye movement, central scotoma in a young patient → think optic neuritis.

3. Is there pain, headache, or systemic danger?

   • Eye pain/red eye → glaucoma, keratitis, uveitis.

   • Age >50 + new temporal headache/jaw claudication → giant cell arteritis, treat immediately.

   • Homonymous hemianopia or cortical blindness → stroke pathway, especially posterior circulation.

The lecture’s core message is: young patient + acute unilateral visual acuity loss over hours = retrobulbar optic neuritis; elderly patient + seconds/minutes monocular darkness = retinal/ophthalmic artery ischemia from carotid disease; bilateral sudden blindness with preserved pupils = cortical blindness from bilateral occipital/posterior circulation disease.

Central retinal artery occlusion is now approached as an “eye stroke” requiring urgent stroke-type evaluation and secondary prevention.   Giant cell arteritis must be treated immediately when suspected because delay may cause irreversible visual loss.