How many degrees is 0.4 vision?

Vision and diopter belong to different concepts, and cannot be converted between them. Therefore, there is no specific degree description for visual acuity 0.4 in clinical practice.

Visual acuity 0.4 generally refers to the visual function of the patient reflected by visual examination. The normal person's visual acuity should be about 1.0. When the patient's visual acuity is 0.4, it indicates that the visual function is reduced, and it is generally impossible to accurately determine the specific degree.

When the patient's visual acuity 0.4 appears, it may be caused by myopia, hyperopia, astigmatism and other reasons. Therefore, the patient should follow the doctor's advice to improve the fundus examination and mydriasis, which is helpful for further differential diagnosis.