Congenital retinoschisis (X-linked) shows a characteristic OCT finding of splitting at which retinal layer, and which electroretinographic abnormality is diagnostic?

• A Splitting at the nerve fibre layer; reduced a-wave amplitude on ERG
• B Splitting at the outer plexiform/Henle layer; absent photopic ERG
• C Splitting at the inner nuclear/ganglion cell layer; selective reduction of b-wave with normal a-wave (electronegative ERG) ✓
• D Foveal splitting at photoreceptor layer; absent scotopic ERG

Explanation

X-linked congenital retinoschisis (XLRS), caused by mutations in the RS1 gene encoding retinoschisin (important for cell-cell adhesion in inner retina), shows OCT splitting at the inner nuclear layer and ganglion cell layer (inner schisis). The characteristic ERG finding is a selective, markedly reduced b-wave with a relatively preserved a-wave — the so-called 'electronegative ERG' pattern. This occurs because the Müller cell-generated b-wave (ON bipolar cell activation) is disrupted at the inner retinal level, while photoreceptor-generated a-wave remains relatively intact. Foveal stellate schisis (spoke-wheel pattern) is the hallmark clinical finding on fundoscopy and OCT.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.