Patients with black dots in front of the eyes with the rotation of the eye and like flying mosquitoes, the shape of dots, lines, nets, circles and so on. In the blue sky, white walls and other brighter background, it is easier to find its presence. Flying mosquitoes often occur in middle-aged and older people over 40 years old, highly myopic patients, other patients such as intraocular inflammation or retinal vascular disease, will also form this disease. Most cases of miosis are benign. Since a few cases of miosis are signs of serious disease, experts believe that miosis should be examined by a specialist to rule out vitreoretinal pathology. However, the result of one examination does not mean that there is always no problem. Once there is a flashing sensation, a sudden increase in mosquitoes, or a sense of black shadows in front of the eyes, etc., it is necessary to receive a detailed examination again immediately.