Problems caused by the suns UV rays seem to be common knowledge but it turns out this knowledge is limited to the skin and most people are unaware how damaging ultraviolet light can be to most of the tissues of the eye. What's more, we usually think about protecting our eyes against UV radiation only in spring and summer, when the weather is hot and we spend more time outdoors. However, UV light affects our eyes all year round and we should really be wearing UV-blocking contact lenses or glasses irrespective of the season.
UV light can slowly damage many tissues within the eye. It can cause such diseases as cataracts, keratitis, macular degeneration (which is one of the most common causes of permanent blindness), photokeratitis, pterygium and in extreme cases, cancer. Most of these conditions develop slowly and often people do not notice until they are quite advanced. Fortunately, people wearing vision correction in the form of contact lenses are partially protected against UV radiation, as practically all modern contacts block UV light quite effectively (American Optometric Association recommends those that block 95% of UV-A and 99% of UV-B radiation).