Glasses are a common product in people's eyes. A good pair of eyeglasses online cheap can help solve visual impairments while also enhancing people's image.

Due to the high technological content of eyeglasses online cheap lenses, several concepts must be mentioned when it comes to lenses, such as the design of front and rear surface curvature, lens material, and film function.

Firstly, let's talk about the design of the front and rear surface curvature. Generally, when we make a thin lens with a size of -2.00D, we can use a combination of a front surface curvature of+1.00D and a rear surface curvature of -3.00D, or a combination of a front surface curvature of 0.00D and a rear surface curvature of -2.00D.

In addition, we can also combine the front surface curvature of+4.00D with the back surface curvature of -6.00D, and so on, to produce lenses with a refractive power of -2.00D. These combinations all appear to have a refractive power of -2.00D, but there is a significant difference in imaging quality.

This is mainly in terms of image difference. Under normal circumstances, because the eyeglasses online lens belongs to a small aperture system, only field curvature, astigmatism, and distortion are generally discussed.

Due to the dispersion effect of most optical materials, they can directly change the power of different colored lights. They can also be considered as changes in prism power caused by dispersion at the lens eccentricity point.

So, a good pair of lenses will be very rigorous in material selection. In the adjustment of curvature, it must also follow the appropriate front and rear surface curvature to control aberrations as much as possible. This inevitably leads to an increase in research and development costs, material costs, and equipment costs.