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What are the different types of eyeglasses lenses?

Arnold Zheng 2021-07-08 18:30:54

Spectacle lenses are generally made of glass or resin and other optical materials that have one or more curved surfaces. After polishing, they are mounted in a frame that holds them as a pair of glasses for vision correction or cosmetic purposes.

There are many types of lenses, which can be classified according to different materials, functions and production processes of the lenses. Experts from Lensmart Online will introduce to you the materials of different lenses.

According to the raw materials, lenses can be divided into glass, hard resin, polycarbonate, etc.

●Glass lens——was the first type f lens to be used for ophthalmology. The main raw material of glass lenses is optical glass that has superior optical properties, good transmittance and mechanochemical properties. Glass lenses are stable with constant refractive index which is up to 1.9. Glass lenses can be chemically treated to increase durability and they are scratch resistant. However, glass lenses are heavier than other materials and not as impact resilient, so fewer people are using glass lenses especially with the development of other materials.

●Resin——is a kind of hydrocarbon secretion from plats, especially conifers. The special chemical structure of resin makes it an optimal material for eyeglass lenses. Resin can be classified as natural resin and synthetic resin. Hard resin lens is a kind of lens which is chemically synthesized. Hard resin lenses have several advantages. Compared to glass, hard resin lenses are lighter, more transparent, and more comfortable when wearing them. They have softer surface and more resistant to scratches. In addition, resin lenses are easy to be processed to meet special needs, so they have become the mainstream of lens on the market.

●Polycarbonate lenses——are highly impact-resistant and shatter-proof, which are not easily broken during outdoor activities. Also, polycarbonate lenses are extremely light in weight. They offer 100% protection from the sun’s harmful UV light for the eye. Polycarbonate lenses are the optimal option for eyeglasses. However, due to the high material price and difficulty in production, they are rarely sold in the market.

According to their functions, lenses can be classified as single vision, multifocal, blue-light blocking, polarized, etc.

●Single vision lenses——are corrective lenses for just one single focal length. The lenses are composed of large area for one field of vision whether that is distant or close. They are the most widely used optical lenses.

●Blue-light blocking lens——is a type of digital protective lens that can effectively block harmful blue light with shorter wavelengths and retain beneficial blue light with longer wavelengths, in order to prevent any damage from blue light. These lenses are suitable for heavy users of digital display devices and electronic screens.

●Sunglasses lenses——are designed to protect the eyes from excessive sunlight. With the help of metal powder, the lens selectively absorbs certain parts of the wavelength bands of the sun, blocking harmful light.

●Polarized lenses——are designed to reduce glare. Glare is a shine with strong and dazzling light when the sun hits a flat surface and the light is reflected back into your eyes. Special coating with vertical direction is added to polarized lenses to suppress strong light. Those lenses are most suitable for outdoor sports such a driving, skiing, and fishing.

●Photochromic lenses——or transitional lenses can darken in strong light and become transparent in indoor light. The color of the lens can be adjusted automatically according to the light and ultraviolet intensity. Molecules of silver chloride or silver halide are embedded in photochromic lenses. photochromic lenses are cost effective because they can be used as both prescription glasses and sunglasses.

●Sport lenses——and goggles are used to protect the eye from dust, water, and impact in motion. This kind of lenses are generally made of polycarbonate or hard resin that are highly resilient and tough.

●Multifocal lenses——are a special type of prescription eyeglass lens that offers multiple focal points in one lens, allowing wearers to see things at various distances. The curvature continuously increases from the top of the lens to the bottom. As a result, the bottom part of the lens has more refractive power than the upper part does. Progressive lenses contain three prescriptions in one lens with comfortable transition between them, so one pair of progressive glasses is equivalent to switching to two or more different glasses. A pair of progressive lenses can be made for multiple use, including anti-fatigue,

Based on different processing techniques, there are spherical and aspherical lenses.

●Spherical lenses——are adequate correction when a person has no astigmatism. Spherical lens has a single curve in its profile. When light with different wavelengths penetrates the lens, it cannot focus on a single point on the surface, resulting in aberration. Spherical lenses sometimes affect the quality of the image, which limits the wearer's ideal vision.

●Aspheric lenses——have an oval-shaped surface that gradually changes in its curvature from the center to the edge. An aspheric lens has a thinner curve, which gives the eyewear a more flattering and slimmer profile. Moreover, aspheric lens is impact resistant, so that the wearer can use it safely. The application of aspheric design can provide better aberration for clearer vision. The aspheric lens is lighter, has a more flat curve and looks more delicate. Aspheric design makes it possible for people with high prescriptions to wear a larger selection of frames without worrying about the lenses being too thick.

When you know what kind of materials and techniques are used for glasses, you can pick the most suitable glasses for yourself. Lensmart Online offers a full range of glasses at affordable prices with free international shipping!