Sunglasses Information

Sunglasses have been popular with people for years, both for comfort and as a fashion accessory. Optometrists now believe there is another reason to wear sunglasses — to protect the long-term health of your eyes. Results from a dozen studies over the last 10 years suggest that long hours in the sun without proper eye protection increase your chances of developing eye disease.

In 1988, a study was carried out on 838 people who had long exposure to sunlight. Those who wore no eye protection had three times as many cataracts as those who wore sunglasses. A cataract is a clouding of the eye's natural lens. Based on this study and others, optometrists now recommend that you wear UV-absorbent sunglasses whenever you're in the sun long enough to get a suntan or a sunburn.

Blocks 99% of ultraviolet rays
You should always buy sunglasses with this feature. Long-term exposure to ultraviolet (UV) radiation in sunlight is linked to eye disease. Both plastic and glass lenses absorb some UV light, but UV absorption can be improved by adding chemicals to the lens material during manufacturing or by applying special lens coatings. Look at sunglasses that block 99 or 100% of all UV light. Some say "UV absorption up to 400nm." This is the same thing as 100% UV absorption.

Blocks 90% of infrared rays
Infrared wavelengths are invisible (they are longer than light rays that you can see) and produce heat. Sunlight has low levels of infrared rays, and the eye tolerates infrared well. Research has not shown a close connection between eye disease and infrared rays.

Blue-blocking
Whether blue light is harmful to the eye is still controversial. Lenses that block all blue light are usually amber and make your surroundings look yellow or orange. The tint supposedly makes distant objects appear more distinct, especially in snow or haze. For this reason, amber sunglasses are popular among skiers, golfers and pilots.

Polarized
Polarized lenses cut reflected glare — sunlight that bounces off smooth surfaces like roads or water. They can be particularly useful for driving and fishing. Polarization has nothing to do with UV light absorption, but many polarized lenses are now combined with a UV-blocking substance.

Mirror-coated
Mirror finishes are thin layers of various metallic coatings on an ordinary lens. Although they do reduce the amount of visible light entering your eyes, do not assume they will protect you against UV radiation.

Wraparound
Wraparound glasses are shaped to keep light from shining around the frames and into your eyes. Studies have shown that enough UV rays enter around ordinary eyeglass frames to reduce the benefits of protective lenses. Large-framed wraparound sunglasses can protect your eyes from all angles.

Gradient
Gradient lenses are permanently shaded from top to bottom or from top and bottom toward the middle. Single-gradient lenses (dark on top and lighter on the bottom) can cut glare from the sky but allow you to see clearly below. They are useful for driving because they don't dim your view of the dashboard. But they're not as good on snow or at the beach, especially if they're clear on the bottom. Double-gradient lenses (dark on top and bottom and lighter in the middle) may be better for sports where light reflects up off the water or snow, such as sailing or skiing. Double-gradient lenses are not recommended for driving, because they make the dashboard appear dim.

Photochromic
A photochromic glass lens automatically darkens in bright light and becomes lighter in low light. Most of the darkening takes place in about half a minute, while the lightening takes about five minutes. They come in a uniform or gradient tint.

Ground and polished
Some non-prescription glasses are ground and polished when they are manufactured to improve the quality of the lenses. Non-prescription lenses that are not ground and polished will not hurt your eyes.

Impact resistant
No lens is truly unbreakable, but plastic lenses are less likely than glass lenses to shatter when hit by a ball or stone. Most non-prescription sunglass lenses are plastic. Polycarbonate plastic, used in many sports sunglasses, is especially tough but scratches easily. If you buy polycarbonate lenses, look for ones with scratch-resistant coatings.

Lens Darkness
A medium lens is good for day-to-day wear, but if you use the glasses for very bright conditions, choose a darker lens. The color and the degree of darkness do not tell you anything about the lenses' ability to block UV light.

Lenses And Tinting
UV Protection
When the eye reacts to bright light, your pupils constrict, and in the dark, they dilate. When you wear sunglasses with dark lenses, the pupil will dilate in response to the dark filter in front of it, permitting more light into the eye. This is the reason why it is important that sunglasses have filter qualities in addition to a dark colour. Sun rays contain ultra violet. UV is not a light, it is a radiation. It is precisely for this reason that you should only ever wear sunglasses with 100% UV protective lenses. All our designated sunglass lenses, include 100% UV protection.

Polarizing Lenses
When the eye reacts to bright light, your pupils constrict, and in the dark, they dilate. When you wear sunglasses with dark lenses, the pupil will dilate in response to the dark filter in front of it, permitting more light into the eye. This is the reason why it is important that sunglasses have filter qualities in addition to a dark colour. Sun rays contain ultra violet. UV is not a light, it is a radiation. It is precisely for this reason that you should only ever wear sunglasses with 100% UV protective lenses. All our designated sunglass lenses, include 100% UV protection.

Tints
Tints reduce light passed through the spectacle lens, so they are useful for some patients who are sensitive to light. Different coloured tints enhance particular colours and some patients prefer looking through a specific tint, which can help some dyslexic patients. Some tinted lenses enhance: contours, depth of field and the colour for ball sports etc. Tints can range in densities from very light tints to extremely dark depending which the patient requires. Specialist medical tints are available as well as specialist occupation tints for welders etc. Various fashion tints are available which enhance the cosmetic appearance, reducing some glare and giving protection from the harmful UV rays without having a full dark lens.

Those at Special Risk
There are some people who are at greater risk for UV-related eye damage. People with certain eye diseases, such as macular degeneration or retinal dystrophies, need to protect their eyes whenever they go outside, no matter how briefly.

Cataract Surgery Patients
Thousands of people have cataract surgery each year. During this procedure, the eye's natural lens is removed, leaving the eye more vulnerable to UV light. During or after cataract surgery, the natural lens is usually replaced by an intraocular lens (IOL). Older intraocular lenses absorb much less UV light than ordinary glass or plastic eyeglass lenses. Manufacturers of IOLs now make many of their products UV absorbent. If you have had cataract surgery and your IOL is not the newer UV-absorbent type, you may want to wear sunglasses and a hat for added protection.

Contact Lens Wearers
Contact lenses by themselves will not protect your eyes from UV light. Many types of contact lenses are available with UV protection. If you do not have contact lenses that absorb UV light, you still need to protect your eyes with sunglasses.

Photosensitizing Drugs
Photosensitizing drugs — drugs that make your skin more sensitive to light — can make your eyes more sensitive to light as well. You should discuss precautions at the practice if you are taking any of the following drugs:

• Psoralens (used in treating psoriasis)
• Tetracycline
• Doxycycline
• Allopurinol
• Phenothiazine

Wear UV-absorbent sunglasses and a hat whenever you go outside for as long as you take the drug.

Special Situations
Ordinary sunglasses, even the best, cannot protect your eyes from certain intense light sources. Arc welding, tanning lights, snowfields or gazing directly at the sun (especially during a solar eclipse) can damage your eyes. Looking at any of these light sources without adequate protection can cause a painful corneal condition called photokeratitis or even a permanent loss of central vision.

Cost
The best sunglasses offer 100% UV absorption, the best optical quality and are the least likely to break. Yet they don't have to be expensive.