Flashes of light on the side of the eye may be caused by myopia or precursor lesions of fundus diseases. 1. Myopia: flashes of light in the side of the eye are more common in people with high myopia and older age. As myopia deepens and age increases, vitreous degeneration will lead to vitreous crumpling, and pulling on the retina will lead to flashes of light. 2. Fundus diseases precursor lesions: the side of the eye feel flash, may be the precursor of vitreous detachment, vitreous clouding, retinal detachment, retinal detachment and other diseases, there are a small number of people who have a flash feeling after the vitreous detachment, in the posterior detachment of the vitreous body, it will involve the retina, resulting in small retinal cracks, the need to go to the hospital in time to consult the doctor under the guidance of treatment. The side of the eye feels flashing, it is recommended that the patient should go to the hospital in time, to clarify the cause of the disease, and follow the doctor’s instructions for standardized treatment.