On every glasses prescription I dispense for distance glasses, there is a stamp that says “UV protection”. That way, I won’t forget to write it — I want everyone to have it. Ultraviolet rays can contribute to many eye diseases, including cataracts, growths on the eyeballs, retinal damage, and eyelid and eye cancers.
The ultraviolet protection coating is made up of chemicals which absorb ultraviolet light, preventing the transmission of the rays through the lenses into the eyes. The chemicals form a dye which is painted onto the lenses. The dye can be clear, as in regular eyeglasses, or tinted darkly for sunglasses.
One of the most frequent questions I am asked is “what kind of sunglasses should I get?” The most important requirement of sunglasses is that they block at least 99% of UV rays. This means that UVA and UVB rays are blocked. Some sunglasses will say “absorb up to 400 nm” which is the same thing. Remember that UV rays can penetrate clouds and haze, so it is important to wear them for all outdoor activities, not just on sunny days.
The UV rays are more intense during mid-day, summertime, around water and snowfields which can reflect light from below, and at higher altitudes. Wraparound sunglasses are best since they offer more protection. Even contact lens wearers with UV protective contacts are not protected from harmful UV rays to the eyeballs and eyelids.
Tinting color and darkness is based on personal preference, not medical reasons. Colors may be gray, brown, or amber, but none is more protective than the other. The same goes with the darkness of the tint. Clear lenses with 100% UV absorption are just as good as the darkest lenses. Some people are very sensitive to bright lights, and others feel they don’t see as well with darker tints. This is especially true for those with eye diseases that affect vision in lower light conditions such as cataracts and macular degeneration. Reflexive, or transition, lenses are convenient since they turn dark in UV rays and lighten when indoors. These lenses don’t get quite as dark inside a vehicle since the windshield blocks some of the UV light required to darken the lenses, so if you’re light sensitive even on cloudy days, get regular sunglasses. Polarized lenses cut down on glare from reflected light coming from snow or water surfaces, and usually give clearer vision, but again don’t affect the UV light transmission.
Don’t forget about protection from physical objects such as stones or fingernails! Sunglasses should be made from materials which are impact resistant, such as polycarbonate, to keep from shattering if they’re hit or fall off. If you’re an active outdoor person, like the Lady Docs, you’re at risk for eye injuries. Polycarbonate lenses are light but can scratch easily, so choose scratch-resistant coating.
Finally, there are many well-known and expensive brands of sunglasses, such as Ray-ban or Maui Jim. They may be more expensive and stylish, but they are not necessarily better! One can find good sunglasses almost anywhere. Optical quality is important, though, since waves and distortions in the lenses can cause headaches, blurred vision, nausea, and dizziness. To check the optical quality of the lenses, hold the lenses at a comfortable distance and look through them at a rectangular object such as a window or floor tile. Close one eye and slowly move the lenses sided to side and up and down while looking through them. The lines of the rectangle should remain straight. If the lines are bent or wiggly, choose another pair of sunglasses!
So, whether you like the looks of Jackie-O, Bono, or Elton John, or have your own personal style, don those sunglasses and enjoy the rest of your summer!