A large difference in vision between the two eyes may be due to refractive error, which is categorized into physiological and pathological. A small difference between the two eyes is called physiologic refractive error. If the difference between the two eyes is too large, i.e., moderate or high refractive error, it will not only cause discomfort to the patient, but also affect the development of the eyes to a certain extent. Refractive error can be caused by the deepening of myopia in one eye, resulting in an imbalance of vision between the two eyes, or it can be caused by trauma, surgery and eye diseases, such as corneal scarring caused by corneal rupture and perforated ulcers after corneal surgery and internal eye surgery, which can lead to the formation of refractive error. If the refractive error is caused by refractive error, glasses can usually be considered to correct it, while those caused by eye diseases are usually not correctable. It is recommended that patients go to the hospital in a timely manner to determine the cause of the disease and follow the doctor’s instructions.