Before glasses need to carry out regular optometry, in fact, different times of the day, the results of optometry are not the same. The morning is usually the best time of day to get the best results. This is because when the eye sees far and near different objects, it depends on the contraction and relaxation of the ciliary muscle and pulls the thickness of the lens to adjust the focal length. After a night's rest, the ciliary muscle can be completely relaxed, which is the most accurate optometry results. If chosen in the afternoon or evening, after a day's use of the eyes, the ciliary muscle is in a state of fatigue, then the optometry may be high. Wearing such glasses may not feel any discomfort at the time, but dizziness and dry glasses may appear two or three days later.