When it comes to eyeglass online lenses, we usually talk about the film layer the most, and the design of the film layer generally requires waterproof film, anti fouling film, anti reflective film, and hard film.

Generally, as the refractive index increases, the amount of light reflected by the lens also greatly increases. Therefore, high refractive index lenses require very high anti reflection coatings, usually requiring multi-layer coating.

As for waterproof film, when large angle water droplets hit the surface of the lens, they will leave no marks like water droplets hitting lotus leaves.

Most modern eyeglass online lenses are made of resin materials, which cannot be compared to previous glass lenses in terms of hardness. Therefore, it is necessary to improve the hardness and scratch resistance of lenses through coating, with hardness almost equivalent to glass.

Of course, good lenses are relatively expensive, partly due to the high cost of materials and equipment, as well as the different coefficients of expansion of different film layers. Therefore, there is a great emphasis on the selection of eyeglass online coating materials.

With the improvement of cultural level and quality of life, more and more elderly people have a great demand for reading books and newspapers. However, presbyopia is inevitable, so progressive lenses have emerged, that is, a pair of lenses with multiple or even countless focal lengths, to meet the needs of both near and far use of a pair of glasses.

At first, there were bifocal lenses, which used one degree for far distance and one degree for near distance. This technology was relatively simple but had large blind spots and poor aesthetics. Later, there were trifocal lenses, but the appearance of blind spots within the relative distance was inevitable. With the development of technology, it gradually emerged.