Judging the pros and cons of sunglasses can be examined from both quality and aesthetics. Aesthetics have personal factors, and quality has certain standards. The quality of sunglasses mainly refers to the quality of the lens. The current standard in the world is the US Food and Medical Hygiene Inspection Service (F·D·A) standard.
1. According to the F·D·A standard, the lens should filter out more than 90% of the ultraviolet light in the sunlight while protecting the light transmittance. The lens should be labeled “UV-100PROTCT10N”. When 100% of the UV filter is removed, it should be attached. The "UV-400PROTCT10N" label, so it is important to look at the UV label on the lens.
2, the lens can not have the "degree" of optical lenses. Generally, if the diopter exceeds 15%, it will feel dizzy when worn.
3. The lens must have a high strength and pass the impact test. In general, the strength of plastic sheets (propionic acid or cellulose acetate), resin sheets, and glass sheets is as small as possible.
How to distinguish the quality of sunglasses lenses
1, the material of the lens
Glass lens: wear-resistant, but relatively speaking, it weighs more than other materials, it is also easy to break.
Polymer resin lens: This lens component is lighter than glass lens, impact resistant, not easy to break, but the hardness is low, so it is easy to fluff and it is easy to have scratches.
2, the refractive index of the lens
The higher the refractive index, the thinner the lens and the higher the price. Such as the optical characteristics of the lens: sunglasses are flat mirrors, can not have diopter, and should not have optical defects affecting vision.
The simple identification method is to place the sunglasses in front of the eyes, observe the distant targets through the lens, such as window frames or door frames, and then move the glasses up and down, the target should not have swing and wave deformation.
3, the color of the lens
Sunglasses have dark and light, and there should be no color distortion. The choice of the color depth of the lens should be determined according to the location of the desired activity. Different colors and different occasions should be used to select different colors. The color of the lens will affect the shading effect. Dark sunglasses are required for sunglasses to effectively block summer glare, but if you are riding or driving, you should not choose lenses that are too dark. In addition, when sunglasses are used for daily driving, they also need to have the ability to recognize different color signal lights.