Choose a Lens in 3 Minutes

1. Refractive Index of the Lens

The refractive index refers to the ability of the lens to bend light. If the degree of myopia is less than -4.00, you can choose a lens with a refractive index of 1.60. If the degree of myopia is between -4.00 and -8.00, a good choice would be 1.60, 1.65, or 1.70. If it is greater than -8.00, it is recommended to choose a 1.74 lens. Choosing a lens with a lower refractive index at this point will increase the lens's quality, but also increase the burden on the bridge of the nose.

2. Material and Thickness of the Lens

The thickness of the lens is related to factors such as the diopter, refractive index, frame size, pupil distance, astigmatism axis, lens properties, and optical design. Although it is commonly thought that thinner lenses are better, this is not always the case. Thin lenses are lighter and more aesthetically pleasing, but they may not have the same optical quality or comfort as thicker lenses. In terms of material, glass lenses have become less popular as they are heavier and more fragile, especially for children. Nowadays, resin lenses have improved in hardness and are lighter and more comfortable to wear thanks to better hardening and coating processes.

3. The Abbe Number and Curvature of the Lens

The Abbe number, also known as the dispersion coefficient, indicates the amount of dispersion in the lens. Values typically range from 30 to 58, with a higher value indicating less dispersion and less influence from the prism effect of the lens on the decomposition of white light. The curvature design comes in two forms: spherical and aspheric. Aspheric lenses have better image quality and are thinner.

4. Light Transmittance and Color of the Lens

Lenses with multiple layers of anti-reflection film, colorless lenses, and aspheric ultra-thin lenses have better light transmittance. For jobs that require clear, stable vision and color recognition, such as students, drivers, surgeons, and artists, colorless and transparent lenses are the best choice. For example, if a driver wears dark-colored lenses, their judgment of distance may become inaccurate, which is dangerous. On the other hand, light-colored or color-changing lenses can block the damaging effects of ultraviolet rays while also improving wearing comfort when exposed to strong light. 

5. Special Functions of the Lens

Some lenses have special functions, such as anti-ultraviolet, anti-blue light, anti-dust, anti-infrared, high temperature resistance, oil resistance, acid and alkali resistance, anti-dispersion, anti-deformation, anti-glare, etc."