Opticians and expensive thinner lenses

jase1

I'm always being pestered by opticians and on-line spectacles companies regarding how much better these higher-index lenses are... I've never been convinced.

I have a fairly high prescription (-5 or worse on both eyes) and have had the standard lenses before ... never saw a problem with them. So I decided to do a little test. I bought glasses on a "buy one get one free" and selected the 1.67 lenses for the main pair as advised... but refused the upgrade on the second spare pair, bought the same frames and just selected the standard CR39s on the second.

Now I favour quite small frames with correspondingly small lenses. But even I was shocked to discover that the difference between the two is barely noticable, and I needed a ruler to realise that the difference in edge thickness was less than a millimetre.

So what exactly is the point in spending the extra £60?

I understand that strong prescription plus large frames = jamjar bottoms. But I think there is an awful lot of salesmanship going on here and an awful lot of people spending far more than they ought to. Some online places recommend 1.74 lenses for my prescription -- a price hike of £130 over standard lenses.

The_Next_Verse

I have a high prescription (-13 in both eyes).

For my prescription it does make quite a bit of difference to the sizes, but (like you) favour the smaller frames so you can't really tell unless I take them off and you look closely!

I guess it probably depends on the prescription as to how useful it actually is.

pmduk

The rule is buyer beware like most consumer situations. The opticians probably make more money by selling upgrades, hence their doing it.

tidus

Are the frames identical? If not then you can't just measure the edge thickness to make a comparison. I assume you are measuring the lens thickness on the outside edge.

You need to measure the distance between the centre of your pupil, when looking straight ahead, to the widest point of the lens.

If this measurement is larger on the pair with the higher index lens this would explain why there is less difference than you might expect. The wider this measurment, the thicker the lens will be.

In a like for like comparison a 1.67 should be 35-40% thinner.