Do High Index Lenses Come with UV Protection?
What is the function of a pair of eyeglasses?
UV Protection with High Index Lenses
To correct for visual impairments, of course, and reestablish clear, crisp vision. That, of course, is the primary role that eyeglasses fulfill. There are, however, secondary services that eyeglasses provide to us, and some are not as readily apparent as one might think.
One of these services is to block harmful UV light from striking the eye and causing either short- or long-term damage to it. Overexposure to ultraviolet light – a natural byproduct of the sun – can damage the eye as surely and demonstrably as it damages the skin. We usually take precautions against sunburn, but are we as diligent about the UV rays that enter our eyes?
Ultraviolet light can damage the eye in two ways. Focused, concentrated exposure over a short period of time can cause a sort of eye “sunburn” known as photokeratitis. Effects of this type of exposure are usually not permanent but it is still an undesirable, uncomfortable condition that one should strive to avoid. Symptoms of photokeratitis include:
- Greater production of fluid (watery eyes)
- Painful reactions or sensitivity to light
- Discomfort akin to having a foreign substance in the eyes
- Redness and swelling
Long-term exposure to UV radiation is even more harmful. Effects include damage to the retina that is often permanent and an increased risk of developing cataracts. Many who suffer these eye conditions later in life attribute them to the simple aging; in actuality they can often be traced to simple UV overexposure caused by an intake of ultraviolet light in short bursts over the course of many decades.
Fortunately, those of us who wear glasses can take precautions against UV overexposure with a minimum of effort. All one need do is determine the level of UV protection that eyewear lenses provide. Standard plastic lenses filter out a high percentage of UV light, and UV protective coatings can be applied to them to increase the blockage rate to 100%. If you wear or are considering the purchase of high index lenses, no further action is warranted; high index material already provides 100% protection against UV light transmittal. Since full UV light blockage is already present and cannot be increased, the addition of a UV coating to high index lenses is unnecessary.