The degree of myopia of 0.4 is about 200-250 degrees, and each person will have a difference in the degree due to the compensatory ability of the eye. Usually people with strong myopia may be even more than 300 degrees, and if the compensatory capacity is weak, maybe 150 or 100 degrees may make the vision drop to about 0.4. But no matter how many degrees, vision loss to 0.4 needs to be corrected with glasses, especially in children. Because this vision has already affected the normal life, and if children do not wear myopic glasses, it is easy to cause fatigue and lead to more rapid growth of myopia. So whether it’s an adult or a child, it’s usually recommended to wear myopia glasses. If it’s an adult, you can also consider wearing contact lenses or undergoing myopia laser surgery or crystal implant surgery to correct and improve your vision in a timely manner.