How thick should glasses lenses be?

real1314

When you buy glasses, you get offered thinner lenses, but there's no real detail on how thin your lenses are likely yo be / how much thinner you can get them, as suppliers don't seem to state exactly what materials they will use.

Does anyone know of any way of finding out how thin lenses should be?:cool:

McKneff

Dont understand your question really, or should i say i dont understand why you need to know
you can have thin lenses, or ultra thin lenses,

I am very short sighted and I know that mine would be like jam jar bottoms if i didnt buy thinner lenses.

All you need to do is ask the optician to see some samples.
There really is no need for you to know about materials used. Why would it be anything other than glass or plastic.

SpikyHedgehog

My opticians willl talk me through the process, showing me how thick unthinned lenses would be (like McKneff, I'd have jam jars) and discussing which lenses are best for thin-ness, cost and durability. I know we discussed last time the fact that different shaped lenes end up different thicknesses.

amibovvered

Long time since I wore glasses but when I did, they were the jam-jar variety. I was told I couldn't have plastic lenses because although they would be lighter than my glass lenses they would have to be even thicker. Glass lenses could be made thinner but they will still weigh the same as the density of the glass is the same. Probably doesn't answer your question, but then I didn't understand it either!

mishkanorman

It depends on a few variables, are you short sighted or long sighted ? Astigmatism ?

Here is a good calculator, bear in mind that frame edges are normally a good mm.


CR39 is basic plastic, glass is thinner than plastic equivilent (marginally) but will be heavier (noticably) higher the index thinner the material.
Polycarb is thinner than plastic but scratches VERY easily,

Frame shape also varies the thickness, feel free to post your prescription

hth,

mishka

Tigsteroonie

An optician once showed me how thick my lenses would be if I didn't have them thinned - worse than the bottom of glass coke bottles :rotfl: If you ask your optician, s/he may well have similar samples.

And it wasn't just a marketing trick - they made me a spare second pair (for emergencies) without thinning so I could tell the difference.

suki1964

This is where you need an dispensing practicioner with experience as every prescription is different.

Everything depends on your prescription and the frames you choose

for example, in my case, just changing the frame type I have gone from paying for the ultra thin to just plane thin as my frames required a thicker lens and my prescription means its the middle of the lens which is the thickest

Hermia

As other people have said they might have samples. They should also be able to explain what the thickness will be with different frame types. I have to have the thinnest lenses (£££££!) as my prescription is so high. I have seen the difference between those and the normal ones and it is very big. I think I would struggle to wear normal thickness ones as they would be so heavy and would like awful.

geri1965_2

I also pay a lot of money for my lenses to be thinned down, but they are still pretty thick at the sides! I generally chose dark plastic frames so they don't look as noticeable.

getmore4less

There are quite a few materials with different refractive indexes than can vary the thickness.

typicaly 1.5 upto 1.9

There are also different lens profiles which change the look and thickness

Also you can machine them to make them thinner as well.

there is quite a good table of uses here
http://www.optical4less.com/ourlens/

Higher index usualy means higher density so heavier but less material so lighter.