June 20, 2011 
Dark sunglasses without a proper filter can actually cause harm…
Behind the dark glass the pupil opens, and the glass does not protect against penetration of harmful rays. So how to preserve good vision?
Ultraviolet radiation is part of the invisible spectrum of light. The source of this radiation is sunlight, welding and very intense light of lamps based on mercury, which are, for example, used at night sporting events.
Dr. Ellen Marmuri from Mount Sinai Hospital Medical Center points out that the best protection for the eyes provide some good glasses. Except that they will look good on you, sunglasses (the bigger and darker the better), have a glass from 98 to 100% UV protection, which protects against skin cancer.
However, be careful because many sunglasses do not have the protective glass. Examine them with your optician who can test them with the photometer for UV protection.
If the glasses that you like do not provide at least 98 percent protection, ask your optician to add a protective layer.
Prolonged exposure to sunlight without proper protection can be dangerous because ultraviolet light can damage the cornea, increasing the chance of developing cataracts, and also the risk of macular degeneration of the retina.
Taken from: www.net.hr