How to make the lenses thinner?
The factors affecting the thickness of the lenses are not just the lens itself, but a combination of multiple factors:
- The same prescription power (sphere power), the same frame, the higher the refractive index of the lens, the thinner the processed lens (as shown in the figure below);
- The same prescription power, the same refractive index, the smaller the frame width, the thinner the processed lens (as shown in the figure below);
- The same refractive index, the same frame, the pupillary distance also affects the thickness of the lens. Use the center beam of the frame you selected, add the width of the lenses, then subtract your pupillary distance. The smaller the difference, the better the lenses effect.
How to choose the best lenses for your glasses?
At the same prescription power, the higher the refractive index, the thinner the lens.
A refractive index of 1.50 or 1.56 can be selected within -3.00~0, a refractive index of 1.56 or 1.60 can be selected for -5.00~ -3.00, a refractive index of 1.67 can be selected for -8.00~-5.00, a refractive index of 1.74 can be selected for over -6.00.
See the picture below:
1. Choose high-index lenses
In brief, the higher the refractive index of the material, the slower light moves through it, which results in greater bending (refracting) of the light rays. So the higher the refractive index of lens material, the less lens material is required to bend light to the same prescription power as a lens with a lower refractive index.
In other words, for a given eyeglass lens power, a lens made of a material with a high refractive index will be thinner than a lens made of a material with a lower refractive index.
2. Choose an aspheric design lens
In addition to choosing a lens material that has a high index of refraction, another way to give your lenses a slimmer, more attractive profile is to choose an aspheric design. Aspheric designs — where the lens curvature changes gradually from the center of the lens to its edge — enable lens manufacturers to use flatter curves when fabricating eyeglass lenses, without degrading the optical performance of the lenses.
Because aspheric lenses are flatter than conventional (spherical) lens design, they cause a less unwanted magnification of the wearer's eyes, for a better appearance. In some cases, aspheric designs also improve the clarity of the wearer's peripheral vision.
Most high index plastic lenses are made with aspheric designs to optimize both the appearance and the optical performance of the lenses.
All the lenses of VlookOptical are aspheric designs.
Generally, lenses with astigmatism exceeding 2.00 and ADD exceeding 2.00 are specially customized, so the production cycle will be extended.
Please assure the accuracy of your prescription before placing your order.