Medical experts advise the public on the importance of wearing sunglasses to protect the eyes from UV for adequate protection, experts recommend sunglasses that reflect or filter out 99-100% of UVA and UVB light, with wavelengths up to 400 nm.
Brites sunglasses and Sunmax sunglasses provide UV 400 protection.
Sunglasses offer Protection against excessive exposure to light, including its visible components. The most widespread protection is against ultraviolet rediation, which can cause short-term and long-term ocular problems such as photokeratitis, snow blindness, cataracts and various forms of eye cancer.
Follow these sunglass buying tips:
- Check lenses to be sure the tint is uniform, not darker in one area than another. With gradient lenses, be sure the tint lightens gradually from top to bottom.
- Hold the sunglasses at arm’s length. Look through them at a straight line in the distance, such as the edge of a door.
- Slowly move the lens across the line. If the straight edge distorts, sways, curves or moves, the lens has imperfections.
- Canadians enjoy outdoor living, and there are many benefits from this lifestyle. However, it is important to recognize the sunlight is a substantial source of UV radiation which may damage tissues of the eye. At risk from sunlight, or strong artificial UV sources, are the ocular surface (snow blindness and pterygium), the lens (cataract) and the retina (eclipse blindness and macular degeneration).
Ultraviolet radiation is divided into two major bands, UV-A and UV-B. UV-A is longer wavelength radiation, close to blue in the visible spectrum, that usually induces skin tanning and browning, and has been implicated in skin aging. UV-B is more active, shorter wavelength radiation that causes blistering sunburn and is associated with skin cancer.
Excessive exposure to intense sunlight, or to an artificial source such a a welding arc of suntanning lamp, can burn the surface of the eye, (cornea and conjunctiva) much like a sunburn on the skin. The risk is highest in environments where much UV is reflected, such as snow or water. Although snow blindness (photokeratitis) may be painful, it is usually self-limited with recovery in one or two days. Chronic sun exposure also contributes to other ocular surface problems such as pterygium.
Cataract (clouding of the lens) is a major health problem in Canada and the most common surgical procedure among the elderly. Globally, cataract causes half of all serious visual impairment and affects 20 million people. Several laboratory and epidemiological studies have suggested a link between sun exposure and cataract. There is debate about how close this linkage is for one common form of cataract (nuclear sclerosis) but measures to reduce UV exposure should reduce the risk of at least two types of cataract (cortical and posterior subcapsular).
Macular degeneration (age related damage in the central vision area) is the major cause of blindness among Canadians over the age of 50, and is an increasingly important problem as our population ages. Both UV and deep blue light have been shown to be damaging to the retina in laboratory studies, and a number of scientists have postulated that UV and blue light may contribute to retinal aging and macular degeneration. Epidemiological studies to date have not demonstrated any clear relationship, except possibly for some severe forms of the disease that seem associated with a history of greater blue light exposure.