Myopia in one eye and normal in the other is known clinically as refractive error. When one eye is nearsighted and the other eye is normal, you need to go to the hospital first for an optometric examination to determine the refractive state of your eyes. I. Causes: 1. Physiological causes: If one eye is normal and the other eye is myopic, the difference in refractive error between the two is not more than 100 degrees, which is usually considered a physiological cause; 2. Pathological causes: If the degree between the orthoptic and myopic eyes is more than 100 degrees, it may lead to visual abnormalities in non-corrected cases. For patients with monocular myopia, early correction is needed, which may lead to amblyopia or strabismus if they are in this state for a long time. Second, the treatment method: 1. If the patient reaches a level that affects normal vision and the usual eye requirements are high, glasses are needed to improve the situation. The myopic eye can wear lenses with myopia, and the other eye wears lenses without degrees; 2. If the difference between the degrees of the two eyes is relatively large, more than 250 degrees, the use of frame glasses is not effective at this time. Patients can consider using contact lenses, such as soft corneal contact lenses or rigid corneal contact lenses. If the patient is older than 18 years old, after a rigorous examination, corneal laser surgery can be considered to solve the problem of monocular myopia. Usually, they need to develop good eye habits, pay attention to proper posture for reading and writing, rest their eyes properly to relieve eye fatigue, look far away more often, increase outdoor exercise appropriately, and go to the hospital for regular optometry.