How to choose the right Sunglasses -For Men and Women - part 2
Do you love how cool your sunglasses make you look? If you really want to be comfortable in the glare and protect your eyes -- and your children's eyes -- from future cataracts, there is more to choosing sunglasses than just looking cool.
Although the human body is remarkable at replacing some damaged cells, the cells in the lens of the eye can’t be replaced. Damage from ultraviolet and (to a lesser degree) infrared rays can build up over a lifetime and lead to cloudy areas of the lens of your eye called cataracts. It's hard to see through cataracts, and they often require surgical removal. Macular degeneration, an eye condition resulting from damage to the retina, also may be accelerated by too much unfiltered sun blasting the retinas.
The main enemy is ultraviolet rays. You need to filter as many of these as you can away from your eyes. Most sunglasses, coated with UV blockers, block the ultraviolet B rays, but the cheaper ones may cheat a little on ultraviolet A. Examine the label. (Some contact lenses also block UVB -- ask your optometrist.) Look out for the CE or BS EN 1836:2005 marks when choosing your sunglasses - this ensures that they provide a safe level of protection from the sun’s damaging UVA and UVB rays.
Apart from UV, brightness is an issue. What people don't realise is that going from inside to outside involves confronting light thousands of times brighter than what has entered the eye the moment before. Brightness is a comfort issue -- it's uncomfortable to go into the sun from the shade and to have undimmed light flowing into your eyes
So the darker the lens in your sunglasses the better? Clear glass transmits 90% of light. As the glasses get darker, less and less light penetrates. Lightly tinted lenses let in 75% to 80% of light. Military standards specify that only 15% of light should penetrate. "You can still see very well with 10% to 12% of light only," explains ophthalmologist Dr Lee Duffner. "I recommend glasses in the 20% range."
The overall best colour is grey, advises Duffner, which absorbs light across the spectrum equally.
Around 8% of men but far fewer women have colour deficiencies (or colour blindness). Depending on your deficiency, Duffner explains, you need to select a certain tint of sunglasses: "Bronze is not good for men with a green deficiency. Green is not good for anyone with a red or green deficiency. Grey is safest for men. Women should choose grey, green, or brown,” he suggests.
Rose-tinted glasses. Are they a good way to see the world? "Pink isn't a good colour for anyone to get," Duffner says.
There are amber-coloured lenses called ’blue blockers‘. For a while these were recommended for tennis players. "These absorb not only ultraviolet, but all blues in the colour range," Duffner notes. Some people say this makes for sharper vision, but they did a study and showed that they do not block UV very well and may cause the pupil to dilate and let in more ultraviolet
Another popular option is ’polarised’ sunglasses. "These are very helpful against reflected light (such as on water, snow or the road)." The light particles called photons travel in a wave form, Duffner explains. Polarised sunglasses, which have a protective layer bonded on much like the tinted film on car windscreens, admit only vertical waves. Since most of the reflected waves are coming in horizontally, those are blocked.
As for mirrored sunglasses, Duffner is sceptical. "These aren't really good protectors," he says. "If you are worried about UV, these should not be your first choice."
How about those gradient glasses -- dark at the top and then lighten toward the bottom? "The most bothersome (reflected) light comes from the bottom," notes Duffner.
Parents who put sunglasses on their babies have the right idea, according to ophthalmologist Dr Steven J. Lichtenstein. Everybody should wear sunglasses, he says. "I see young adults with cataract changes all the time."
Wearing sunglasses is especially important between 10 a.m. and 2 p.m. Even children with dark eyes, which provide partial protection, should wear them.
As with adults, children who wear prescription glasses can get prescription sunglasses. Clip-ons are also made for children’s glasses. Duffner recommends wraparounds for people who are out a lot, although these are not as good in prescription form.
For children, you need wearability. "Something comfortable, something they will keep on," says Lichtenstein.
*Glass or plastic?
Glass is adequate at blocking UV, but polychromic sunglasses -- glass lenses that get darker as you encounter brightness -- are the gold standard. "Those really work," says Duffner, but glass sunglasses are heavy, despite being long-lasting. "I had a patient today," Duffner laughs, "who told me he had been wearing the same polychromic glasses for 24 years." Glass doesn't scratch as easily as plastic.
What about driving? Sunglasses can cut glare, but never wear them at night. The Highway Code states that you should never wear sunglasses or tinted lenses for driving at night, or when visibility is poor; for example, if it is raining heavily, snowing or foggy
The Eyecare Trust.
Dr Lee Duffner, professor of ophthalmology, University of Miami, spokesperson for the American Academy of Ophthalmology.
Dr Steven J. Lichtenstein, Louisville ophthalmologist, chairman of the American Academy of Pediatrics' section on ophthalmology, University of California.
Reviewed on February 26, 2011
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