The diagnosis of myopia is not based on visual acuity, but on refraction. For adults, myopia is defined as an eye with a refractive error of less than -0.50 D. 0.50 D is 50 diopters.
Theoretically, the normal human eye has a refractive error of 0, i.e., orthokeratology. However, due to certain differences in the refractive ability of each person’s eye, 0 to -0.5D, i.e., 0 to 50 degrees, is considered normal. Myopia with a refractive error of more than 0.5D, i.e. 50 degrees, is considered as myopia, and is categorized into different types of myopia, such as mild, moderate, and severe, according to the abnormality of the refractive error.
As can be seen from the above, the diagnosis of myopia relies on the measurement of refraction and has nothing to do with visual acuity. Abnormal visual acuity is only a clue to possible refractive errors and other abnormalities in the eye, and cannot be used to diagnose myopia.
It is recommended that patients with vision loss seek medical attention to evaluate their condition and follow medical advice.