Lens index, thickness and coatings

Below, you can learn more about lens thickness and coatings. Remember, if you have any questions we're here to help make sure you get the frames and lenses that are right for you. Contact us using the details on our contact page.

Understanding refractive index

The refractive index represents how efficiently a lens can refract light. A higher index means a greater refraction of light, which is why a lens with a higher refractive index can be manufactured in a thinner form. The refractive index also depends on the lens material. With plastic it varies between 1.5 and 1.74

Refractive index 1.5
These standard lenses are used to correct minor sight deficiencies up to a value of ±2.00 dioptres. They may be unsuitable for higher values. if you have a value higher than +2.00 dioptres and you still want to proceed with 1.5 index. please be aware the lenses may appear thick and feel heavy, consider choosing a plastic pair to hide the thickness of the lenses. 

Refractive index 1.6
Lenses are usually used for dioptres ranging from ±2 to ±4. They are much thinner and about 20% lighter than standard lenses.

Refractive index 1.67
Extra thin lenses, so thin that high dioptres of between ±4 and ±6 don’t draw attention to themselves – or feel heavy, as they are around 40% lighter than the 1.5 standard lenses.

Refractive index 1.74
super thin lenses which are up to 60% thinner and lighter than the standard version and can correct dioptres from upwards of ±6.00.

Scratch resistant and anti-reflective coatings

Scratch resistant coating or hard coating provide lenses with durability and increased longevity. A Hardcoat provides the best scratch resistance and provides for the most durable ingredient for an AR coating application.

Anti-reflective coating (also called "AR coating" or "anti-glare coating") improves vision, reduces eye strain and makes your glasses look more attractive. This is due to the ability of AR coating to virtually eliminate reflections from the front and back surfaces of your spectacle lenses.