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The Optical Knowledge Portal
Information – Education – Certification

Light protection

Light protection

Sunlight protection glasses, or just sunglasses for short, are normally spectacles with tinted lenses. The lens tint reduces light transmission and glare. People can choose between different hue levels to suit different levels of glare sensitivity. Sunglass lenses are also available in a wide variety of lens colours. They can be manufactured with gradient tints, usually fading from 25% at the top to clear at the bottom, or featuring 25% at the bottom and 60/75/85% at the top depending on their intended use. Sunglasses protect the eyes from harmful UV light.

Sunglasses can be divided into different categories on the basis of their light transmission rates. In Europe, the following classification is used:

 

Filter

Category

Absorption

Description

Usage

0

0 % - 20 %

Very light tint

Limited reduction of sun glare

1

20 % - 57 %

Light to medium tint

Limited protection against sun glare

2

57 % - 82 %

General purpose dark tint

Good protection against sun glare, especially in Central Europe

3

82 % - 92 %

Very dark tint

High protection against sun glare, e.g. in tropical and subtropical regions, on high mountains, over snow fields, bright water surfaces, or in the desert

4

92 % - 97 %

Extremely dark tint

Very high protection against extreme sun glare, e.g. bright snowfields or glaciers. Not suitable for driving use.