High Index Lenses

by Jamie
(UK)

Q: Hello- I just ordered some glasses from Specsavers and was told the 1.74 high index lenses wouldn't be any thinner than a 1.67 lens.


Is that right? I don't understand why!

I have some 1.74 from another opticians and they are pretty thin.

My eyes are +5.75 & +4.75.

Thanks


A: I notice you have hypermetropia, a (+) prescription, and a medium diopter (around 5).

Your lenses are an excellent example of "need to have thinner lenses". Indeed, it would be a good idea to use high index lenses.

It is a fact that different index lenses have different thickness, and usually is a visible difference.

You have (+) diopter lenses, so this type is thicker in the middle and thinner on the edge. Maybe it is harder to observe the different index thickness, but it depends on how big the frame is.

I recommend larger frame for a thinner lens on the edge, so a 1.74 lens would be thinner. There is no way that two different index lenses to be the same thickness.

Maybe is not a big difference like between 1.5 and 1.67, but the 1.74 is thinner for sure than 1.67.

See our article on this topic

Hope this helps,
Arpi

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