Abstract: Microaneurysm (MA) has four types of ultrastructures: Type I vascular endothelium is intact but lacks pericytes; Type II blood vessels have red blood cells in the lumen, but endothelial cells and pericytes are absent; Type III irregularly shaped red blood cell contour in the lumen, part of the lumen is occluded; and Type IV blood vessels are completely hardened. Color fundus photography MA showed small red dots with a diameter of 15-60 μm. Fundus fluorescein angiography is considered to be the gold standard for diagnosis of MA. It is manifested by the arterial phase with sharply defined circles and strong fluorescent spots of varying sizes, and some late fluorescein leakage can be seen. On OCT, MA is a highly reflective ring-shaped cyst structure, which is divided into three types: complete ring-shaped structure type, incomplete type, and non-ring-shaped structure type. The classification of MA by OCTA includes focal bulging, saccular, fusiform, mixed, pedunculated, and irregular. The multispectral ocular fundus imaging 550 nm, 580 nm, and 590 nm are all displayed as small black dots, and in the pseudo-color image, they are displayed as red dots. The multicolor scanning laser imaging can show the MA as small black dots (low reflection signal) more clearly than fundus photography, and the detection rate is higher than fundus photography. (Int Rev Ophthalmol, 2021, 45: 204-210)

Key words: diabetic retinopathy, microaneurysm