Look out for your eyes

The summer sun is here and with it has come warnings for sun-seekers to cover up as they head outdoors.
But there's much more to being sun smart than slip, slop, slap and wrap, with the sun's damaging effects to unprotected eyes.
The New Zealand Association of Optometrists (NZOA) warns excessive exposure to UV, which causes sunburn, can result in snow blindness, and in the longer term may lead to cataracts, macular degeneration and premature ageing changes in general.
Our eyes already have three natural mechanisms to cope with light - our eyelids, our pupils, and our retinas at the back of the eyes, which adapt to different brightness levels.
All three natural mechanisms respond quickly to changes in visible light - but cannot completely keep out ultra-violet (UV) radiation.
For many New Zealanders constantly exposed to the sun, sunglasses are as much a necessity as hats and sunblock.
One of them is top windsurfer Sven Pedersen, who believes most people don't realise that the glare off the water and sand can be seriously damaging for your eyes.
"I can sometimes be out on the water for hours at a time and, even on an overcast day, the glare can get pretty intense so my hat and sunnies are important pieces of gear to me," the 17-year-old from Mt Maunganui said.
"It doesn't really matter if you're out for a fish, or a surf, there are ways and means to protect your eyes, even if it is getting tinted goggles, I just reckon it is so important, especially if you want to keep on doing what you love and not have your sight damaged."
While wearing sunglasses minimises our eyes' exposure to UV radiation, a coloured lens will not necessarily reduce UV absorption - and sometimes will only reduce the amount of light we see. The NZOA urged people to ensure their sunglasses not only reduced brightness - but also protected their eyes from harmful UV radiation.
Optometrist Tony Han, of Specsavers Mount Maunganui, said sun lovers were among the most vulnerable to poor eye health.
"A sandy beach generates about 1.2 times as much UV radiation as you would get from standing in direct sunlight alone because the sand reflects the UV light back on to you and water reflects like a mirror," Mr Han said. "While people are having fun at the beach this summer, I encourage them to think about the risk of UV damage to their eyes. Sun-related conditions can have quite serious consequences, ranging from vision loss to blindness, so it's very important to take the right precautions."
Tauranga optician Max Drennan agreed. He believed swimmers were exposed to the greatest risks, partly because of the many reflective surfaces at the beach or pool and partly because they were less likely to wear eye protection while swimming.
"People are also much less likely to wear their sunglasses when they're actually in the water, so this means they can go for quite long periods of time without protecting their eyes," Mr Drennan said. "Glasses wearers are also at greater risk of exposure to UV radiation because of the inconvenience of trying to wear sunglasses when they're already wearing glasses. This is why it is essential for glasses wearers to invest in UV-safe sunglasses, transitions lenses or to wear contact lenses when they're involved in outdoor activities so they can wear sunglasses."
What to look for when choosing sunglasses
LENS QUALITY: Lenses are the most important aspect of sunglasses. They come in a variety of tints and can be made of glass, various plastics, or polycarbonate.
Glass lenses are generally more resistant to scratching, but can be broken more easily than plastic lenses.
High-quality glass lenses are excellent at selectively absorbing undesirable rays and are available in solid or light sensitive tints. Resin or plastic lenses are safer than glass and often feature a scratch-resistant hard coating, which helps to ensure a long life. Polycarbonate lenses are stronger still and are a must for eye safety when playing sports such as cricket. They offer the ultimate in eye protection and safety and the range of tints is extensive.
LENS COLOURS: Different lens colours and treatments offer differing levels of protection against UV radiation.
Brown or amber lenses are useful for absorbing UV light and blue light. Grey lenses do not distort colours, while polarised lenses absorb reflected light. No sunglass lens, however, is ever dark enough to observe the sun or eclipses.
FRAMES: The New Zealand Association of Optometrists recommends frames that are comfortable, serviceable and fit well on the nose.
Close fitting wrap-around styles offer better protection for not only the eye itself but also for the eyelids and surrounding tissues.
Plastic sunglass frames are generally strong and durable, however, some plastic frames are mass-produced and may not be adjustable.
Metal sunglass frames are usually adjustable but often have more moving parts that will require maintenance. Cheaply made metal frames may be brittle metal and, as a result, less durable.
- New Zealand Association of Optometrists