Macular edema is an important cause of visual impairment in many eye diseases such as diabetic retinopathy, retinal vein occlusion and uveitis. Optical coherence tomography (OCT) provides high-resolution image of retinal microstructures in a non-contact and rapid manner, which greatly improves the ability of diagnosis and follow-up to macular edema patients. OCT has been widely used in the clinical detection of patients with macular edema. No matter what the cause of macular edema is, it can be observed in OCT images that there are spot-like deposits with strong reflection signals in the retina, which are mostly distributed discretely or partially convergent, and are called hyperreflective foci. At present, the nature or source of hyperreflective foci is not clear, however, may involve the destruction of the blood retina barrier, retinal inflammatory reaction, neurocellular degeneration, and so on. These mechanisms are also the key physiological mechanisms in the development of macular edema. The clinical research on hyperreflective foci provides a new direction for understanding the pathogenesis of macular edema and predicting the prognosis of macular edema. The distribution and quantity characteristics of hyperreflective foci may be an important biological marker to predict the prognosis of macular edema.nosis of macular edema. foci provides a new direction for understanding the pathogenesis of macular edema and predicting the prognosis of macular edema. The distribution and quantity characteristics of HRF may be an important biological marker to predict the prognosis of macular edema.