
Ask HN: News site for prescription lenses technology - ben_utzer
I was wondering if someone knows a good news site for news about eyecare technology. I always wondered why, for example, photocromic lenses don&#x27;t exist above 1.71 index.
======
dnh44
Actually they do, in 1.74 index. Thats the highest index lens you can easily
find, not just in photochromic but in clear as well. Tokai make a 1.76 but
they aren't as widely available and I don't think it's easily available in a
photochromic version.

Lenses of an index higher than that are only available in glass but not many
people will pay for or want to wear those because of weight issues.

Please keep in mind though that a higher index lens doesn't mean it's a better
lens even though they're more expensive. As a general rule the higher the
index the worse the optical properties. The only thing higher index lenses are
good for is that they can be made thinner due to the way a higher refractive
index material bends light.

Anyway to answer your question I'm not aware of any great site for optical
news. It'd be nice if someone made one. I sometimes have a look at the
following sites.

[http://www.optmagazine.com](http://www.optmagazine.com) //this one is a bit
sarcastic

[https://www.opticianonline.net](https://www.opticianonline.net)

[http://www.optiboard.com/forums/](http://www.optiboard.com/forums/)

