- Posted by Admin on December 8, 2009
Hi there,
Sorry I missed last Friday.
I was going to tell you about high index lenses so I’ll just do that now.
You’ve maybe heard the term high index but don’t really know what it means. It refers to the density of the lens. The higher the index the denser the material, and the more quickly light will travel through it. With respect to lenses the higher the index of the material the thinner the lens can be to get the same power. And what that means to the spectacle wearer is that the higher the index the thinner your lenses will be and so the better your spectacles will look.
The type of high index lens you will be recommended will depend very much on your prescription and to some extent the frame that you choose.
If you have quite a small prescription then there is no need to go to a high index material, unless you choose a rimless frame in which case we would recommend high index as the lens is more robust.
For moderate prescriptions say 3.5dioptres to 5.00 dioptres we would suggest a mid-index such as 1.56 or even 1.6.
For prescriptions of 5 dioptres to 6.50 dioptres we would maybe suggest a higher index lens such as 1.67, and above that you ca go to a 1.74.
As well as the density of the lens going up with increasing index you will find that the price will go up as well, which is why we don’t recommend a 1.74 for a simple prescription. You wouldn’t notice any difference really in the lens thickness and it would just be a waste of money.
When you are buying glasses its always worthwhile asking what the best index would be for your prescription and frame. Upgrading the index can have a significant effect on the appearance of your spectacles, and, as you wear them on your face, you want them to look as good as possible.
Hope this helps.
What do you think I should talk about next week?
Cheers,
Carla
P.S. Are you getting excited about Christmas?
