Human eyes have the “membrane” and so do lenses. There are different types of coatings for eyewears.

The structure of sunglasses consists of several layers from different materials, each layer has a specific function or a role. The followings are the main types of coating structures:

1. Base layer

The base material of sunglasses lens is usually a strong and lightweight plastic material, such as PC, CR-39, TAC, etc.(see blog: Sunglasses Lens Materials). The base material is the main structure of sunglasses lens, and choosing the right base material is an important factor to optimize the function of sunglasses.

2. Scratch proof coating

Scratch resistant coating of glasses lens is usually made of polymer materials such as polyurethane or polymethyl methacrylate (PMMA). By using a hardening solution containing an organic matrix and an inorganic ultra-particulate substance, a hard film is applied to the surface of the lens, which provides both toughness and hardness to the surface of the lens, thus improving its resistance to abrasion.

3. Reflection proof coating

Lenses anti-reflection coating is usually composed of several layers of metal oxides, such as titanium dioxide or fluoride, also known as anti-reflection film. It is a transparent material with different refractive indices and thicknesses coated on the front surface of the lens, which uses the principle of light interference to reduce the excess reflected light on the surface of the lens. After the lens is coated with the anti-reflective coating, the transparency of light is increased and the wearer will feel that the glare is reduced and the vision is more realistic and brighter, which can improve the wearer’s comfort and vision.

4. UV protection coating

Ultraviolet rays are not visible to the naked eye, the main source of ultraviolet rays in nature is the sun, and the main rays that can cause harm to the human body are UVB and UVA rays, and prolonged exposure to ultraviolet rays can lead to eye diseases such as cataracts, macular degeneration and so on. Therefore, a special coating that filters out harmful UV rays must be added during the manufacturing process of sunglasses to protect the eyes from UV rays.

5. Waterproof coating

The waterproof layer is a special polymer material that prevents water from entering the lens, keeping it dry and clear.

6. Oil proof ating

The anti-oil layer is usually made of silicone or fluorine material. Its main function is to prevent fingerprints, grease and other contaminants from adhering to the surface of the lens, keeping it clean and clear. This layer prevents blurred vision or degradation of optical performance due to accumulation of dirt, and reduces scratches or abrasions on the lens caused by wiping the lens.

7. Polarized coating

The polarizing layer effectively absorbs reflected glare perpendicular to the transmission axis, while allowing polarized lenses to absorb 99% of ultraviolet light. This layer eliminates reflected light and glare, improves visual comfort and clarity, and protects the eyes from ultraviolet light.

8. Salt proof coating

The anti-salt film layer prevents lens damage and aging due to salt water erosion, which is essential for glasses used at the beach and swimming pools, and enhances the durability of the lenses, thus prolonging the life of the glasses.

9. Decorative coating

The decorative layer is usually a transparent colored coating used to change the color and appearance of the lens. This layer is available in a variety of colors to meet the individual needs of the consumer.


Posted: December 10, 2023
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