Usually, the result of the naked-eye visual acuity and refractive error do not match, so the naked-eye visual acuity of 4.9 alone can not determine the patient’s degree of myopia. In general, only based on the naked eye visual acuity, can not be calculated through a simple formula to calculate or speculate the patient’s myopia, vision measurement will be affected by a variety of factors, and myopia is an objective value, so if you want to check the specific degree of myopia, you need to go to the regular hospital ophthalmology line optometry examination. Naked eye vision of 4.9 belongs to a mild vision loss, may be related to overuse of eyes, it is recommended to maintain good eye habits, less electronic products, avoid reading in a place with too much light or darkness, and take a proper rest after using your eyes for about 30 minutes. It is recommended that patients with vision loss should consult a doctor in time to assess their condition and follow the doctor’s instructions for treatment.