A 26-year-old woman hit her forehead on a car dashboard during a road traffic accident. Visual acuity is 6/60 in the left eye, there is a prominent relative afferent pupillary defect, colour vision is severely reduced, but the optic disc and retina appear completely normal on fundoscopy. CT shows a fracture near the left optic canal. The most likely diagnosis is:

• A Optic nerve avulsion
• B Indirect traumatic optic neuropathy ✓
• C Retinal detachment involving the macula
• D Occult globe rupture

Explanation

Indirect traumatic optic neuropathy follows blunt head trauma transmitting force to the optic nerve within the canal, producing profound vision loss, RAPD, and dyschromatopsia with a completely normal initial fundus because the injury is posterior to the lamina cribrosa; disc pallor appears only after 3 to 4 weeks. Optic nerve avulsion shows a visible excavated disc, retinal detachment would be visible peripherally, and occult rupture usually shows hyphaema, irregular pupil, or low pressure.

Reference: Yanoff and Duker Ophthalmology, 5th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.