the price of the sunglasses does not guarantee the amount of uv protection. more importantly if you are wearing sunglasses that are darkly tinted yet do not offer much uv protection the back of your eyes will be exposed to more uv light not less. this is because the tinted lenses will encourage your pupils to dilate (enlarge) which will then allow more uv light to reach the back of your eye. although this uv exposure may not take its toll immediately increased uv exposure has clearly been linked to many forms of eye disease that may not show up for decades. age-related macular degeneration and cataracts are just two forms of delayed eye disease that good (not necessarily expensive) eyeglasses can help prevent.
is wearing cheap sunglasses better than no sunglasses if my child and i will be out in the sun for an extended period?