Earlier in the week we had a client in the shop who was surprised about our lens dispensing techniques. We accurately calculated the actual thickness of his lenses in the new frame he had chosen. It was important to him to have an aesthetically beautiful pair of glasses, and because of the actual power of his lenses he expressed real concern of what the finished glasses might look like. During the consultation we were able to discuss various options and calculate the exact thickness of his lenses in the various frames that suited him (one of those actually was a rimless frame).

Because this is a pretty common concern for many glasses wearers, we thought that it might be a great topic for the blog, especially since many people probably don’t even know about this service. Calculations like these are of particular interest to those with higher prescriptions.

With the calculated information, we are now able to individually recommend best suited lens types, that are the thinnest and of course the lightest for a given prescription.

Spectacle lenses of similar power and diameter can be made with different thickness. This is possible by using different lens materials with different refractive indexes. Thanks to higher refractive indexes, lenses of similar power can be made with less lens material.

Having said that, in some cases the difference in lens thickness between two different lens materials is so small, that it doesn’t warrant the extra expense. The reduction in lens thickness does not relate to the extra cost.

To advise on the “right” lens choice, that would then be our responsibility.

In order to calculate the lens thickness of various lens materials, the computer program we use requires various measurements and individual details.

Relevant for a meaningful calculation are the shape of the frames, the exact centration details (pupillary distances and center heights) and of course the lens prescription for each eye. That’s it!

Our lens thickness calculation program shows for this particular customer that by using a thin lens with a refractive index of 1.7, his lens center thickness would be 3.8mm, with an edge thickness of 1mm! Not bad when your prescription is +6.00 diopters. (in comparison a “standard” lens would have resulted in a lens being 7.1mm thick and of course a lot heavier).