The causes of small black dots in the eyes are as follows: First, if there are small black dots on the whites of the eyes may be scleral pigmentation, or it may be a feature of the position of the scleral vessels across the eye into the ball, this part of the scleral tissue is thinner, so it can see through to the color of the inner choroid. Second, if there is a fixed black spot in the visual field of the eye, it may be a foreign body embedded in the cornea, or it may be a pre-crystalline pigmentation occurring in iritis, and the large pigment may be manifested as a black spot in front of the eye when seeing things, or it may be a manifestation of a higher local density of cataract. Third, if there are floating black dots in front of the eyes when seeing things, this is the performance of vitreous opacity commonly known as mosquitoes, divided into physiological and pathological two cases. Physiological mosquitoes are mainly seen in myopic patients, usually more people with eyes and the middle-aged and elderly groups, belong to the performance of vitreous liquefaction degeneration, is a physiological change so will not affect the visual function. Pathological vitreous clouding is mostly associated with fundus diseases, such as diabetic retinopathy, retinal detachment and other patients, need to actively intervene.