What is the primary diagnosis for a patient with sudden monocular vision loss and a pale retina with cherry-red macula on fundoscopy?

The primary diagnosis for a patient presenting with sudden monocular vision loss accompanied by a pale retina and a characteristic cherry-red spot at the macula is central retinal artery occlusion (CRAO). In CRAO, the blockage of the central retinal artery impairs blood flow to the retina, leading to ischemia and resulting in a pale appearance of the retina. The cherry-red spot occurs because the fovea, which is an area of thinner retinal tissue, allows the underlying choroidal circulation to be seen against the pale, ischemic retina. This clinical finding is considered a classic sign of CRAO and aids in confirming the diagnosis.

Other conditions can present with sudden vision loss, but they do not typically exhibit this specific combination of findings. For instance, cerebral edema would more likely cause visual disturbances related to neurologic issues rather than direct retinal findings. Central retinal vein occlusion may cause vision loss but is usually associated with a more diffuse retinal hemorrhage rather than a pale retina and a cherry-red spot. Retinal detachment typically presents with symptoms such as flashes of light or floaters and does not show the specific pale retina and cherry-red macula pattern seen in CRAO. Therefore, the presence of the described retinal findings is key to establishing the