In the previous article, we discussed “What are carbon fiber glasses?”. In this article, let’s talk about “Which type of lens is used to correct myopia?”.
What symptoms does myopia have?
Myopia is a problem related to the eye's ability to focus on distant objects. The manifestation of myopia is that blurred vision at a long distance. But near-distance vision is good. Early myopia often has long-distance vision fluctuation and squinting when looking at distant objects. Because looking close need not or less use an adjustment, and set function is weakened correspondingly. Those with high myopic have poor far vision, often accompanied by poor night vision, floaters, and other symptoms. Changes in the fundus of the eye can occur to varying degrees. It can form irregular shape white atrophy spots and so on.
Which kind of lens can correct myopia?
Myopia is corrected by glasses with concave lenses, which are the thinnest in the center and thicker at the edges. The strength of the lens used to improve myopia is measured in diopter (D). The prescription for myopic glasses always begins with a minus sign. The higher the magnification of the lens, the better the effect of correcting myopia. High refractive index lenses are usually recommended to correct myopia with a diopter greater than -3.00. The lenses are thinner and lighter than regular plastic lenses, making them more attractive and comfortable. At the same time, an anti-reflective coating is strongly recommended for the correction of myopia lenses. The augmented reality coating eliminates scattered reflections in the lenses, making them look thinner and more attractive.
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.
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