The lifetime of contact lens
Traditional type: the replacement cycle is more than 3 months, not more than 1 year, that is, we say we abandon after one season, and we can abandon after half a year and a year.
Frequent-change type: the replacement cycle is more than 2 weeks, not more than 3 months, that is, we often say that we throw them after 1 month or two weeks.
Abandoned type: as a one-time use, common for the day use.
Contact lenses, like food, have an expiration date. For example, the shelf life of daily contact lenses is one day (after it is opened), and can not exceed this time. And the life span of a pair of glasses depends on how long you use them each day. Although different lens materials determine different wear times, we recommend that soft lenses should not be worn for more than 8 hours per day (do not wear soft contact lenses to sleep). Traditional contact lenses can be used for a long time, so the lens is easy to produce protein-lipid deposition, and then they are easy to cause eye surface inflammation and hypoxia reaction. If conditions permit, it is recommended to choose the frequent-change type and discard type, the shorter the cycle, the healthier.
Pay attention to the color of your blue-blocking glasses.
For children, their lenses are relatively clean and clear, and the blue light transmittance is higher than that of adults, which is more harmful to the eye. On the complementary color principle of optics, a good pair of blue light glasses should not be deep orange, but light yellow. The complementary color to cyan is orange. So, in order for the glasses to absorb blue light and filter it out, they must appear blue's complementary color yellow, otherwise, they violate the optical principle of absorbing blue light.
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Can the TR90 frame be changed?
TR90 material was originally made in Italy. It is difficult to color the frame, and usually, the color is painted on the outside. It can float in saltwater. It is suggested that the lens should be a water first to prevent overheating of the lens. Then, at the end of the nose, hinge, or the temple, carefully fold it in until it is comfortable to wear. You can use a household hair dryer to blow heat first, which can play the role of softening. Note that the hairdryer should be moved when heating, and do not aim at only one place. TR-90 is the most popular ultra-light material in the world at present.
How do you clean an eyeglass case?
Sprinkle a little water on the glasses case first, to soften the dirt and dust on it. Brush gently with a soft brush to avoid damaging the glasses case. The inside of the case needs to be cleaned with a brush. Use a rag to wipe the surface of the glasses case for moisture and dirt. Wash it several times with a wet cloth. Use paper towels to dry the surface and interior. And then dry in the sun.
Why is a prescription for glasses different from a prescription for contact lenses?
The frame glasses degrees are the optometric degrees of the eye, and the difference between the frame glasses degrees and the contact lens degrees is mainly due to the different contact distances between the two lenses and the eye. Usually, degrees of contact lenses and glasses need to be converted by a professional through vertex diopter. The conversion formula is Fc=Fs/(1-d×Fs). In the formula, Fc is the diopter of contact lens, Fs is the diopter of glasses frame lens, and D is the distance between frame glasses lens and cornea. Assuming that the prescription of frame glasses is -4.00d and the distance between lens apex is 12mm, the prescription of contact lenses is -4.00/ [1-0.012×(-4.00)] = -3.82d.
The refractive index of the lens is related to the thickness of the lens.
The main factors that determine if a pair of finished glasses are beautiful, portable, and comfortable depending on the thickness and thinness of the processed lenses. Depending on the material, the index of refraction is different. If you just look at the refractive index, the higher the refractive index at the same degree, the thinner the lens will be. The thinner the lens will be, and the more beautiful the lens will be. However, the higher the refractive index, it is not the better. You can choose the refractive index lens suitable for yourself. But the refractive index is not the only factor that determines lens thickness. Think about the distance between your eyes and the size of the frames you choose, which can affect the thickness of the lenses you match. The larger the pupil distance, the smaller the frame, and the thinner the lens.