A 49-year-old man suffers sudden painless loss of vision in this eye. What caused it?
Correct. Retinal artery occlusion causes infarction of the retina and sudden vision loss. The whitening of the retina, such as you see here, is due to ischemic retinal swelling. The surrounding normal retina is transparent, so it allows reflection of the orange color of the underlying choroidal vessels. Ischemic swelling destroys retinal transparency in the infarcted region. The red spot in the center of the white patch is called a “cherry-red spot.” It appears red because the foveal retina is nourished by the choroidal arteries, which are not occluded.
Incorrect. Retinal vein occlusion can also present with acute and painless vision loss. However, ophthalmoscopy would show flame-shaped hemorrhages around the optic disc extending along the branches of central retinal vein.
Incorrect. Retinal detachment presents with sudden-onset flashes, floaters, and visual field loss, which is not this patient’s problem. It appears as a billowing elevation usually more obvious in the retinal periphery. It can be overlooked unless the optic fundus is viewed through a widely dilated pupil by expert examiners.
Incorrect. Choroidal melanoma can disturb vision if it is located under the fovea, but vision loss would be slowly progressive. Ophthalmoscopy would show a faint brownish lump under the retina.