Neuro-Ophthalmology
Core concepts
Master the afferent and efferent pathways: optic nerve, chiasm, optic tract, and visual cortex, plus the pupil light reflex and its defects (RAPD, Horner, Adie). Know the pattern of visual field loss by lesion site: monocular (optic nerve), bitemporal (chiasm), homonymous (retrochiasmal).
Understand optic neuritis (pain on movement, RAPD, decreased colour vision), papilloedema (bilateral disc swelling from raised ICP), and ischaemic optic neuropathy (altitudinal defect, sector pallor). Know the pupil abnormalities and the third, fourth, and sixth nerve palsies.
Traps
- Missing an RAPD in unilateral optic neuropathy.
- Confusing papilloedema with papillitis (bilateral vs unilateral, disc leakage).
- Attributing a homonymous defect to the eye rather than the brain.
- Overlooking Horner syndrome in a patient with neck pain (carotid dissection).
Rule of thumb
Localise the lesion by field pattern: monocular → optic nerve; bitemporal → chiasm; homonymous → retrochiasmal.
Worked example
A patient with sudden painless visual loss, an altitudinal field defect, and sector disc pallor. This suggests non-arteritic ischaemic optic neuropathy; check for giant cell arteritis risk factors and consider urgent steroids if suspected.