Are you rough with your sunglasses or constantly losing them? These are common complaints we hear from our patients. These patients tend to buy inexpensive sunglasses due to the fact that they are constantly replacing them. It is important however to be aware of the differences in quality and Ultra Violet (UV) protection in sunglasses.
So what is the difference between high quality (and more expensive) sunglasses and the cheapies you can buy at your local gas station? UV protection! It’s a vital, all-important difference, and one that you shouldn’t ignore.
THE IMPORTANCE OF PROPER UV PROTECTION
More and more scientific evidence conclusively shows that exposure to UV-A, UV-B and UV-C has adverse long and short-term effects on your vision and the health of your eyes. If you are exposed while unprotected to excessive amounts of UV radiation over a short period of time, you are likely to experience a condition called photokeratitis, which includes symptoms of pain and extreme light sensitivity. Long-term exposure to any of the types of UV radiation can cause more serious problems, including macular degeneration, retinal damage, cataracts, and even cancer. The damage these conditions cause to the retina are usually irreversible.
You cannot determine the amount of UV protection a pair of sunglasses will provide by their price, colour, or by the darkness of the lenses. The regulations put forth by the government (Health Canada) are voluntary, which means that disclosure regarding the amount of UV protection is optional.
In addition, the labelling on sunglasses is often misleading. The label can read ‘100% UV block’, but that gives no indication as to which type of UV is blocked or for how long. For example, cheap sunglasses might have only 100% UV-A blocked but 0% block for UV-B or UV-C. Your eyes need protection from all types of UV – A, B, and C.
Another important consideration is the means by which the lenses are protecting your eyes from UV light. Many of the cheaper sunglasses have a sprayed-on UV coating which often get washed off after the first few times you clean your glasses. This leaves your eyes unprotected. The UV protection is gone, but the dark tinting on the lenses remains and causes your pupils to dilate (because they think it’s night time). A result of this is that your eyes receive even greater doses of UV radiation than if you weren’t even wearing sunglasses in the first place!
Higher-end sunglasses will have the UV inherent to the lens itself, which means that even when the lenses are washed (or scratched), the UV protection remains in effect to protect your eyes. Polarized lenses allow for the UV protection to be in the middle of the lens and maintain proper UV protection regardless of wear or tear.
PROTECTING YOUR VISION
Optically speaking, as you curve a lens, power is induced. Since most sunglasses are curved to wrap around the shape of the face, the lens must be curved as well. In cheaper sunglasses this amounts to visual distortion from the sunglass lenses. This can be perceived as a blur, changes in depth perception, or image size differences. Cheap sunglass lenses are made from moulded plastic which is then bent into the sunglass frame. Quality sunglass lenses are made from ground glass, polycarbonate or plastic. The optics are then accounted for once they are placed in the frame to minimize or create ‘distortion-free’ vision.
Glare comes from sunlight reflecting off the surface of the environment around you as well as the reflections from the sunlight on your sunglass lenses. Quality sunglasses not only protect your eyes from UV light and bright visible light, they also have scratch-resistant coatings and anti-reflection coatings to decrease glare. Approximately 8% of light traveling through your sunglasses is reflected. Anti-reflection coatings eliminate 99.5% of UV light thereby greatly improving the quality of your vision. Another important factor to consider is the condition of your lenses. As scratches accumulate over time on your lenses, your ability to see through them will deteriorate. Anti-scratch coating will aid in prolonging the life of your sunglasses.
Living in the beautiful Okanagan means lots of sunny days, so I always tell my patients to invest in a quality pair of sunglasses. You’ll look good, see clearly, and, most importantly, be protecting your eyes. At iSight Optometry we have a great selection of high quality sunglasses (both prescription and non-prescription) from top designers and brands. Find yourself a pair of sunglasses that are not only fashionable but sure to protect your eyes this summer. Stop in to iSight Optometry!