Ischemia of the superficial retinal nerve fiber layer leads to which finding?

• A. Cotton wool spots
• B. Retinal detachment
• C. Neovascularization
• D. Macular edema

Answer: (A)

When the superficial retinal nerve fiber layer becomes ischemic, the flow of axoplasm along the nerve fibers is disrupted. This causes microinfarcts in the nerve fiber layer, leading to the accumulation of prelaminar material and swelling of the axons. The resulting pale, fluffy white patches are cotton wool spots. They reflect localized ischemia of the nerve fiber layer rather than a detachment, new vessel growth, or fluid leakage.

Retinal detachment involves the physical separation of the neurosensory retina from the underlying pigment epithelium, not RNFL ischemia. Neovascularization is a response to broader retinal ischemia and VEGF-driven vessel growth, which is not what cotton wool spots themselves represent. Macular edema results from breakdown of the blood-retina barrier and fluid accumulation in the macula, not the focal nerve fiber layer ischemia that creates cotton wool spots.