There are mainly two types of optical lenses: glass and resin. The glass sheet has high hardness and is heavy and fragile; the resin sheet has strong light transmittance, light weight and not easily broken, and can protect against ultraviolet rays, but has poor wear resistance. Those with high refractive error should choose resin lens to reduce the weight of the lens; children should not wear glass lens, because it is fragile and the risk is high. The thickness of the lens depends on the power and refractive index. The center of myopic lens is thinner and the periphery is thicker. The higher the power, the thicker the lens, and the higher the refractive index, the thinner the lens. Those with high refractive errors are best to choose high refractive index lenses.
The relationship between glasses parameters and lenses:
pupil Distance: The distance between the center points of the pupils when the eyes are looking straight ahead or when the visual axis is parallel!
Lens refractive index: refers to the ratio of the speed of the lens through the air and through the lens material. The larger the value, the thinner, smaller and thicker the lens. There are four main categories: 1.5 series, 1.6 series, 1.67 optical lens series, and 1.74 series.
Dispersion coefficient (Abbe number): This is a value generally between 31-58 (for resin lenses). The larger the value, the greater the dispersion phenomenon of the lens. Smaller, the higher the clarity, the higher the fidelity of seeing the object. Generally, the most expensive 1.67 lens has the smallest dispersion coefficient and the lowest definition (so if your power is not too high, choose carefully, not the price is high).
Hardening technology: Coat a layer of high hardness material on the surface of the resin lens that is easy to wear , To increase wear resistance.
Coating technology: The surface layer of the lens is coated with a film composed of many metal trace elements to increase the light transmittance of the lens (above 94~99%), see Things are more clear and complete. At the same time, the special film also has anti-fog and anti-radiation functions.
The common ones are green film, blue film, optical lens purple film, gold film, and red film. Among them, blue film, red film and purple film are basically radiation-resistant lenses, and blue is the best. The most formal is the green film, which is basically used for brand-name lenses. Good lenses also have anti-radiation function, and the lenses are whiter, and the film is natural and beautiful.
spherical/aspherical: spherical lens looks curved; the advantage of aspherical surface is that the lens looks less circle, the eyes will not be significantly reduced due to the concave lens, and the other will not There is obvious bending.
Resin lenses should not be wiped hard
Many people think that resin eyeglass lenses can be wiped as hard as glass lenses, but they don’t know. The resin lens has a low hardness and is prone to scratches, so it cannot be wiped like a glass lens.
resin frame glasses have weak resistance to external forces. One-handed removal is likely to cause deformation of the glasses due to uneven force. Therefore, it is necessary to insist on using both hands to remove them. At the same time, the focus lens should be used to check whether the screws of the glasses frame are loose and the glasses are deformed. If the screws are found to be loose, they must be tightened in time to prevent the lens from falling off and causing scratches. If the glasses are deformed, go to the optician to repair them in time.
When using resin glasses, clean the glasses regularly to keep them clear. When cleaning, do not use paper towels or lens cloth to wipe directly, but rinse with clean water first. If it is stained with grease, use dish soap or neutral soap to clean it, rinse with clean water, and then dry naturally, or use a soft tissue Or wipe off the water gently with the glasses cloth. When wiping the water, try not to rub the glasses directly, and avoid scratching with sharp and hard objects.
When cleaning the glasses, it is best to hold the nose bridge of the frame with one hand and gently rinse the lens body with the other hand. Nowadays, many optician centers offer services for ultrasonic cleaning of glasses. As long as the glasses are placed in a super aspherical mirror sound washing machine filled with clean water, they can be cleaned in 5 minutes by the action of ultrasonic waves.
Glass lenses include optical glass lenses and high-refractive-index lenses (commonly called super thin sheets), It has high hardness and good wear resistance. Generally, its quality and various parameters will not change with time, but the impact resistance and weight of glass lenses are slightly inferior to resin lenses.
Resin lenses are generally much lighter than glass lenses, and their impact resistance is better than glass lenses, but their surface hardness is lower and they are more likely to be scratched. Resin lenses and coated lenses are soft because of their soft characteristics, so you should always be careful not to let the mirror directly touch hard objects. It is best to clean with water (or a small amount of detergent) when scrubbing, and then use a special test cloth or high-quality tissue paper Blot the water droplets on the glasses lens. In addition, the coated lenses should be used with caution in places with poor environmental conditions, so as not to be stained with dirt and difficult to clean.