Dr. Fred Arima answers questions about UV light, and how it effects our eyes.
Q: What is UV ?
A: UV is the high energy part of sunlight. Natural sunlight is composed of a spectrum of colors. Sunlight is composed of a spectrum of colors such as infra- red, red, green, yellow, blue, and ultraviolet (UV). Infra-red and ultraviolet light is not visible to the human eye.
Q: Why the concern about UV?
A: Because UV has so much energy, long term exposure to UV has been found to cause damage to tissues of the human body. We all know about the connection between UV and skin cancer. Keep in mind these are cumulative effects. The more exposure to UV the more likely damage to human tissue. This is similar to radiation exposure. The more you are exposed to it, the more likely you will develop problems like cancer.
Q: What effect does UV exposure have upon the eyes?
A: Long term UV exposure damages the tissues of some structures of the eyes that are very important for vision.
These structures are the cornea, the lens, and the macula (center part of the retina).
Q: How does UV damage parts of the eye?
A: The cornea may be damaged by a painful sunburn called photo keratitis as well as a growth called a pterygium. The lens is damaged by the formation of cataracts, and UV damages the retina by a disease called macular degeneration. Just as long term UV exposure accelerates aging of your skin. It accelerates aging of parts of your eye.
Q: What is UVA and UVB?
A: Ultraviolet, UV, can be subdivided into UVA and UVB. UVA causes more damage to the macula, retina.
UVB causes more damage to the cornea and the lens of the eye.
Q: How can I protect my eyes from UV damage?
A: Fortunately there are lenses designed to block UV from passing through the glasses lens and striking and entering your eye.
These UV blocking lenses should be worn with activities in the sunlight or around activities that produce UV such as welding and UV
Q: Does a darker colored lens block more UV?
A: No. Not necessarily. Since UV is invisible to the human eye, a dark lens or a clear lens may have the same amount of UV blocking. You
cannot see it.
Q: If I can’t see it, how do I know my lens is blocking UV?
A: Your optical will have lens meters that can measure the UV blocking ability of your glasses. Both sunglasses and clear lens glasses can be
Q: Aren’t the UV blocking tags on sunglasses proof of lens UV blocking?
A: Unfortunately not. Our FDA publishes guidelines for UV protection, but does not routinely test the lenses sold in the USA for compliance.
As in all things, you must rely upon reputable brands and vendors. Of course you should also be aware of “knock off” or counterfeit
sunglasses. The best way to be sure your lenses block UV is to take them to your optical to have them tested.