How To Use Contact Lens Correctly?
Check your eyes for abnormal cases. Do your eyes sting or dry? If so, it is recommended not to wear contact lenses for the time being. Look in the mirror to see both eyes carefully, if it is red and swollen or if is both eyes full of bloodshot? If you do, you can no longer wear contact lenses, and you can go to a professional store for inspection. After putting on the contact lenses, block the left and right eyes respectively to see if the vision of one eye is clear. If the eye vision has decreased or blurred, check if the lens is dirty. If the lens is still the same, you should go to a professional store to find out the reason.
The origin of modern eyeglasses
The origins of modern glasses can be traced back more than 1,000 years. In the Middle Ages, the reading stones used by monks were glass spheres, sometimes filled with water and placed on objects to magnify them.Glassblowers in Italy created reading stones, similar to modern hand-held magnifying glasses. The reading stone can be placed on the wearer's nose or in front of the face. Later, Spanish craftsmen built the first cobra-framed temple in the 17th century. They tie ribbons or strings to the frames and tie them around the user's ear.
In the 18th century, Edward Scarlett created the first wearable glasses, providing more comfort for eyewear wearers. These early glasses had glass lenses embedded in heavy frames made of wood, lead, or copper. Natural materials of leather, bone, and horn were later used to make the frames. In the early seventeenth century, lighter steel frames were invented. As eyewear continued to evolve and prescription accuracy improved, the trend for eyewear to become more fashionable began. In the 18th century, bifocal lenses appeared, making it possible to correct upper myopia and lower presbyopia. Later glasses were designed to be fixed by a ribbon or by applying pressure to the bridge of the nose. In the 1980s, plastic lenses were introduced, providing a more durable alternative to glass lenses. Ultimately, the glasses used today are the result of centuries of technological and intellectual advances.
The refractive index of lens
Refraction law is discovered by Dutch mathematician Snell.It is the law that determines the direction of refracted light in the phenomenon of light refraction. When the light from the first medium (refractive index N1) into the second medium (refractive index N2), part of the light from the first medium into the second medium at the smooth interface will be refracted. The index of refraction is the ratio of the speed at which light travels in a vacuum to the speed at which light travels in the medium. For glasses lenses, the higher the refractive index, the thinner the lens, that is, the lens with the same center thickness and the same degree, the lens with the higher refractive index has thinner edges than the lens with the lower refractive index of the same material.
How do myopic glasses work?
The formation principle of myopia is that when the light from the outside world enters the eyeball, it is refracted by the eyeball's refractive system and cannot be accurately imprinted on the retina. The image is in front of the retina. If a concave lens is placed in front of the eye before the light enters the eye, it shifts the focus of the myopic eye from a point in front of the retina to the back, so that it lands directly on the surface of the retina. When parallel light passes through a concave lens, it diverges, meaning that it has already diverged once before entering the eye and then is refracted normally by the eye's refractive system. When the light is refracted through the eyeball, the distance of the image will be longer. So the distance of the image will be correspondingly pushed back compared to the non-divergent light. But it will just fall on the retina, and the image will be accurate in the right place.
How Long Does It Take to Get Used to Varifocals?
When you get a new pair of glasses, you have to get used to them. So, how long does it take to get used to the glasses? Some people only need a couple of days to get used to them while some others may need up to two weeks.
It is normal if you can only see the frame rim of your glasses when you first wear them. The reason for this lies in the brain’s visual center. It needs to adapt the new and greatly improved visual conditions.
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The purpose of glasses donation activities.
Regular social donation activities should be carried out in a planned way. For the poor in the rural areas of the disaster area and the poor in the urban districts, donations of materials or funds can not only feel the warmth and humanistic care of society in life and material, quickly resuming production and rebuilding homes. It gives them a sense of psychological security and stability, which is more practical than physical help.
