This topic should still be fresh in everybody’s minds as it was the subject of the latest SKE blog post. (And if you haven’t read it yet – why not?! Shame on you!)
As discussed, the biggest problem that UV causes to the eyes is cataracts – the clouding of the lens in the eye, that most people will experience as they get older.
When we talk about UV protection, most people automatically think ‘sunglasses’. However it is important to just reiterate that there is a difference between UV protection and sun protection. UV protection on your glasses reduces the amount of harmful UV radiation that enters the eye. Sun protection shades us from the brightness of the sun, much like sitting in the shade or wearing a hat. Confusion can arise because generally the two go hand in hand, in that most sunglasses offer some form of UV protection, however they are NOT mutually exclusive! It is important that you always check what you’re buying – look for the term “UV400” – this denotes that the lenses will absorb UV up to 400nm (the range considered to be harmful to the eyes).
With regard to prescription spectacles, a standard 1.5 index hard resin (CR39) lens will protect against the more intense UVB radiation (100% cut @ 340nm), but a separate coating can be applied to these to make them 100% UV protected, i.e. against UVA AND UVB (100% cut @ 395-400nm). All other higher index materials (“thin & light”) will naturally absorb 100% incident UVA and UVB and therefore no additional protective ‘coating’ is required. The same is true for hard resin photochromic (light-reactive) lenses.
There really are no excuses people – protect them peepers!!