It is not possible to infer the exact degree of myopia based on a patient’s visual acuity of 0.9. Patients need to undergo standardized optometry under the guidance of an ophthalmologist to clarify the exact degree of myopia. 0.9 is visual acuity, visual acuity and myopia are two different concepts. Myopia is to determine the degree of myopia in the patient’s eyes, while visual acuity refers to the resolution of the viewing angle. They are two different concepts, so there is no specific way to convert them, and therefore the patient’s myopia cannot be inferred from the patient’s visual acuity. If you want to determine the specific degree of myopia of the patient, you should be under the guidance of the ophthalmologist through the standardized vision, such as dilated pupil optometry, computer vision, etc., to determine whether the patient is myopic. It is recommended that patients experiencing vision loss should seek prompt medical attention to assess their condition and follow the doctor’s instructions for treatment and care.