What does glass index mean?

The lenses of our standard are monitor glasses and sunglasses with a glass index 1.5. Index stands for the thickness of the lenses. The thickness of the lenses depends on several factors, such as the strength of your eyes and the size and material of the frame.

The thinner the glass, the higher the index

Lenses help you see by bending light. Lenses with a high lens index are lenses that bend light more effectively than other types of lenses because of their high refractive index. This allows people with a strong prescription to wear glasses with thinner, less conspicuous lenses.
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High-index lenses can correct most common refractive errors, including myopia, farsightedness, and astigmatism. People with a lower strength prescription usually notice no difference in thickness or improved vision when they opt for high-index lenses. However, your optician can always best judge what best suits your strength.

The higher the refractive index of an eyeglass lens, the stronger your prescription can be without the lens having to be thicker.

The refractive index is an important factor

For the dilution of the glass, the refractive index of the material is the most important parameter. This index shows how light diffracts in the glass. The higher the refractive index of the material, the thinner the lenses can be made. The disadvantage of a higher refractive index is that the glass reflects more. That is why the lenses of our monitor glasses and prescription sunglasses come with an appropriate anti-reflection as standard.

What are the four factors that determine the thickness of your lenses?

1. Frame size
2. The strength of the lenses
3. The position of the eyes (pupil distance)
4. The type of frame

What are the benefits of lenses with a high lens index?

• They are more aesthetic, thinner and lighter and are less noticeable in frames.
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• They are safer and offer better optical quality.
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• Your frame selection is not limited by high-index lenses. Due to the thin profile, they fit many frames if you have a higher prescription.
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• They are comfortable. High-index lenses do not sit heavily on your nose and ears and are less likely to slip down than thicker lenses.

What is the difference between high-index lenses and other lenses?

High-index lenses are thinner and lighter than other types of lenses. For example, a standard plastic lens (with a refractive index of 1.5) and a high-index lens of 1.67 may have the same prescription, but the high-index lens may be up to 30% thinner.

Can sunglasses have high-index lenses?

Yes, the glasses on our prescription screen glasses and prescription sunglasses can all be equipped with these thin lenses (with a glass index of 1.6 and 1.67).

Extra thin lenses are often chosen to keep the monitor glasses or prescription sunglasses as light as possible and to prevent glass edges from sticking out of the frame. So it looks nicer. And thinner lenses enlarge the eyes less with positive lenses and reduce the size of the eyes with negative lenses.

Are high-index lenses worthwhile?

If you like aesthetics, lenses with a high lens index are a great solution for getting the thinnest lenses for a high prescription.
They are more expensive, but the benefits of lenses with a higher refractive index outweigh the additional costs for many wearers compared to lenses with a lower refractive index.

Your employees are welcome at all Hans Anders offices throughout the Netherlands to wear the right customized screen glasses and Seeh sunglasses. Hans Anders only employs qualified opticians and hearing care professionals. This way, you'll always get the best help when it comes to fitting your prescription glasses or sunglasses.‍