What is the likely cause of visual loss in CRAO?

The correct answer relates to hypoperfusion of the inner one-third of the retina, which is crucial for understanding central retinal artery occlusion (CRAO). In CRAO, the central retinal artery becomes occluded, leading to a sudden reduction in blood flow to the retina. This lack of adequate blood supply primarily impacts the inner layers of the retina, which are particularly dependent on the central retinal artery for oxygen and nutrients.

Without proper perfusion, these inner layers, which include ganglion cells and inner nuclear layers, are at high risk of ischemia and subsequent cell death. This is what leads to the visual loss associated with CRAO. The immediate result is often profound and sudden vision loss, commonly described by patients as a "blackout" or curtain falling over part of their vision.

Understanding this mechanism highlights the importance of timely diagnosis and intervention in CRAO cases to prevent irreversible vision loss. Prompt restoration of blood flow, if possible, can sometimes salvage remaining vision, underscoring the critical nature of addressing hypoperfusion in this context.