Sunglasses can be generally divided into three categories according to use: sunshades, light-colored sunglasses, and special-purpose sunglasses.

The so-called sunshade mirror, as the name suggests, is used for sunshade. In the sun, people usually rely on adjusting the size of the pupil to adjust the luminous flux. When the light intensity exceeds the eye's ability to adjust, it will cause damage to the human eye. Therefore, in outdoor activities, especially in summer, many people use sunshades to block the sun to reduce fatigue caused by eye adjustment or damage caused by strong light stimulation.

Light-colored sunglasses do not block sunlight as much as sunshades, but they are rich in color, suitable for use with various types of clothing, and have a strong decorative effect. Light-colored sunglasses are favored by young people because of their rich colors and diverse styles. Fashion women are even more fond of them. Special purpose sunglasses have a strong function of blocking sunlight. They are often used in the wild where the sun is strong, such as beaches, skiing, mountain climbing, golf, etc., and their UV resistance and other indicators have higher requirements.

Different people choose sunglasses according to different preferences and different uses, but the most fundamental thing is to start from the basic principles of protecting the wearer's safety and preventing vision damage. Reducing strong light stimulus, clear and undistorted vision, anti-ultraviolet, undistorted color recognition, and accurate identification of communication signals should be the basic functions of sunglasses. If the above function is defective, it will lose the function of sunglasses, and it will cause conscious distress such as dizziness, eye swelling, etc. Sometimes, it may also cause unresponsiveness, illusion of color discrimination, inequality of walking vision, and traffic accidents. . Therefore, choosing sunglasses can not only focus on style but ignore its inherent quality.