Retinal microaneurysm
Retinal microaneurysms are focal dilatations of retinal capillaries, 10 to 100 microns in diameter, and appear as red dots.
They are usually seen at the posterior pole, especially temporal to the fovea.
Microaneurysms are the first ophthalmoscopically detectable change in diabetic retinopathy.
Fibrin and erythrocytes may accumulate within the aneurysm. Despite multiple layers of basement membrane, they are permeable to water and large molecules, allowing the accumulation of water and lipid in the retina.
