I recently saw a health show on TV that said you should wear darker sunglasses because they filter more light. Previously, I had heard that darker sunglasses cause the pupil to open wider and make the eyes more vulnerable to harmful light; ergo, you should wear lighter sunglasses with good UV protection. I have very light colored eyes, so my eyes are especially vulnerable to harmful light anyway, which is why I really want to get this right. Can you give me a definitive answer on this one?
— Blue-eyed and concerned
Dear Blue-eyed and concerned,
While the research doesn’t speak to whether the shade of sunglasses affects pupil dilation, it does show more generally that sunglasses can cause pupils to dilate. Dilated pupils are quite vulnerable to damaging ultraviolet (UV) radiation, so sunglasses without UV protection could actually have some shady consequences for the eyes more so than light colored lenses.
Sunglasses vary in their ability to block UV rays, but this variation is surprisingly not related to lens color or tint. Actually, a clear lens coating can protect the eyes from UV radiation. Both non-colored corrective lenses and colored sunglasses can be treated with this clear coating to provide up to 99 to 100 percent UV protection. While that’s the expectation, it’s wise to be wary of glasses that claim to block UV rays without stating the specific level of blockage — these protective glasses are clearly marked. Some manufacturers imply their glasses provide UV protection even though they aren't treated with the extra clear shield. This is because untreated plastic and glass blocks a small portion of UV rays, and some manufacturers' labels may stretch the truth. If you’re looking for additional ways to reduce damage to the eyes you might try a combination of the following: wraparound sunglasses with high (99 to 100 percent) UVB and UVA protection, UV blocking contacts, hats, and avoiding harsh light.
For those with lighter colored eyes, there is evidence to support that fluorescent light and sunlight might feel harsher and even painful for folks with light colored eyes. The reason being that the lack of pigmentation provides less protection against light sensitivity (often referred to as photophobia). People with light eyes are also more vulnerable to UV damage than people with darker eyes.
Hopefully this answer has helped you see a little more clearly which sunglasses can provide you with the most protection.Alice!