The number of degrees of refractive error is not directly related to the number of decimal points of visual acuity, so 400 degrees of myopia cannot determine the exact value of visual acuity. A 400 degree myopia is usually 0.25 decimal point visual acuity, which is the reciprocal of decimal point visual acuity multiplied by 100, but this is a rough estimate. 400 degrees of myopia is moderate myopia, and the patient can see no more than 4.6 naked eye vision, and some patients can see only about 4.2. The results may vary after eye fatigue or after sufficient rest, as each person’s ability to adjust is different. Therefore, if you have 400 degrees of myopia, you need to go to a regular hospital ophthalmology department for a vision check to know your vision accurately. Usually 400 degrees of myopia can be corrected to a normal visual acuity of 1.0 and above. The 400 degree myopia usually affects the normal life or study, and need to wear glasses early. Patients need to pay attention to eye hygiene, less exposure to electronic products, more green plants, more outdoor activities, local massage and hot compresses, and usually do more eye exercises.