Retinoschisis describes a splitting of which retinal layer?

• A. Inner Nuclear Layer
• B. Outer Plexiform Layer
• C. Inner Limiting Membrane
• D. Ganglion Cell Layer

Answer: (B)

Retinoschisis is a splitting within the neural retina itself, not a detachment from the RPE. The classic site of this split is the outer plexiform layer—the synaptic plane where photoreceptor terminals connect with bipolar (and horizontal) cells. When adhesion between cells at this layer is disrupted (as in certain hereditary forms like X-linked retinoschisis), fluid collects and a schisis cavity forms within that plane, usually in the macula.

That’s why the outer plexiform layer is the best answer. The inner limiting membrane is the boundary with the vitreous and isn’t the typical plane of separation in retinoschisis; the inner nuclear layer and ganglion cell layer are inner retinal layers, and while some schisis-like changes can occur elsewhere, the hallmark site for retinoschisis is the outer plexiform layer.