Which structure in the eye is primarily affected by central retinal artery occlusion (CRAO)?

Central retinal artery occlusion (CRAO) primarily affects the retina, specifically the inner layers of the retina that are supplied by the central retinal artery. This artery is a crucial blood supply that nourishes the nerve fiber layer, ganglion cells, and inner nuclear layers of the retina. When the artery becomes occluded, it leads to ischemia, resulting in vision loss due to the damage of these vital retinal structures.

In the case of CRAO, the areas of the retina that are deprived of blood supply quickly show signs of tissue damage, typically presenting as a pale retina with a characteristic "cherry-red spot" at the fovea on examination. This condition underscores the importance of the central retinal artery in maintaining the health and function of the retina.

The cornea, iris, and lens are not directly impacted by CRAO since they receive their blood supply through different mechanisms and do not rely on the central retinal artery for nourishment. Thus, the retina is the structure most critically affected by this vascular occlusion.