Lens Index Explained: What 1.50, 1.67 and 1.74 Mean for Your Lenses

What the numbers mean

The number is the refractive index of the lens material. A 1.74 lens bends light more efficiently than a 1.50, so it needs less material to achieve the same result — and comes out thinner and more elegant. That difference becomes clearly visible as your prescription grows, which is why higher indices exist mainly for stronger corrections rather than mild ones.

Is there a trade-off?

Yes: in general, as the index rises, optical clarity can drop slightly (a lower Abbe value) and a good anti-reflective coating becomes more important. For low prescriptions, a high index offers no visible benefit and simply adds cost, so matching the index to your actual needs is always the smart move.

Which one to choose

Let your prescription decide: a low prescription → 1.50/1.59 is plenty; as myopia increases → step up the index for a thinner, lighter and better-looking lens. When in doubt, our opticians are happy to recommend the ideal index for your frame and prescription combination.