The refractive index of resin lenses mainly has numbers such as 1.49, 1.56, 1.61, 1.67 and so on. The refractive index of the glass lens is relatively high. However, because glass lenses are heavier than resin lenses, and the lenses are easy to break, generally people choose resin lenses more. If the degree of myopia is not very high, it is still more to choose a lens with a refractive index of 1.56.
Generally speaking, a lens with a refractive index of 1.56 is usually selected for a myopia within 500 degrees. The refractive index of a myopic lens can be a convenient reference for choosing a lens. If the power is above 500 degrees, you can choose a 1.56 aspheric lens or a lens with a refractive index of 1.61.
The same power, the same material, the higher the refractive index of the lens, the thinner the lens will be. Generally speaking, if the power is higher, the higher refractive index will be selected Of lenses. Therefore, if the power is above 500 degrees, considering the thickness of the lens, a lens with a refractive index of 1.61 can be selected.
There are many lenses with a refractive index of 1.56 in the market, and the functions are also diverse. Different coatings, the function of the lens are also greatly different, LOHO glasses life is advanced The optometrist reminded that if you choose lenses, go to those formal institutions, and the quality of the lenses will be more guaranteed.
How to distinguish between spherical and aspherical myopic lenses The difference between a pair of eyeglass lenses suitable for individuals is a good lens, and in the glasses, some people have aspherical lenses and some have spherical lenses, and they all say that they are suitable for themselves. Then, the difference between spherical and aspherical eyeglass lenses What is it like? Who are the main people who are suitable for wearing these spectacle lenses? Let's take a look at the difference between spherical and aspherical spectacle lenses with the editor below.
From the appearance of the lens, generally aspherical lens is more beautiful. This is because aspherical lens, under the same material and power, aspherical lens It is flatter and thinner than spherical lenses, so most people with higher power usually wear aspherical lenses. This aspherical lens feels very comfortable after wearing.
If you look at things around the traditional aspheric lens, there will be distortions. The non-spherical design reduces the edge difference of the lens to a minimum. The surface curvature of the aspheric lens is aspherical design, which makes it more natural to see things, with less distortion and more lifelike viewing. Focusing lens
For patients with mild myopia, both spherical and aspherical lenses are worn, and spherical lenses can be selected. But if it is more than -2.00DS and people with astigmatism, it is better to choose aspherical lens, which can reduce the deformation of things very well and is very comfortable to wear.
The higher the degree of spherical lens, the worse the appearance will be. The spherical lens cannot eliminate the difference. The non-spherical lens has a beautiful appearance, reduces the lens phase difference, and can obtain a clearer vision. And after the lens is coated, the aspheric lens has a more perfect visual performance, a clearer vision and more comfortable.
Naked Eye Observation
After understanding the difference between spherical and aspherical surfaces, let’s see how to identify them easily. Compared with the aspherical surface of the same material and the same degree, the aspherical aspherical lens is flatter, thinner, more realistic, more natural and comfortable.
If you look at the coating shape of the lens against the lamp tube, the lamp tube reflected by the spherical lens is generally straight (except for the high-diopter lens); the non-spherical lens is due to the curvature of the surface Different, the shape of the lamp has a larger curvature.
In the eyes of experts, excessive eye use has become the main cause of myopia in adolescents, which includes two aspects: prolonged use of eyes, close-range use of eyes, and improper visual hygiene. This is because children with undeveloped eyeballs suffer from long-term tight close-range use of eyes and poor visual hygiene. For example, students are overburdened with homework, use close-range eyes for too long, and have no eyesight for a long time. Restrictedly playing game consoles, watching TV, playing mobile phones and other small screens can cause changes in the refractive power and anterior and posterior diameter of the eye and cause myopia.