Warming of the Earth's climate system and related increasing concentrations of greenhouse gasses are causing some eye disorders, writes Maria Anguita.

Two years ago, retired teacher Vera started experiencing eye discomfort, irritation and crusting of the eyelids. She was prescribed a short course of antibiotics for what her doctor suspected was a simple eye infection, but several months later she was still having problems.

"My eyes felt constantly gritty and dry, and my lids were red and flaky. I was treated for a range of eye conditions, but nothing seemed to make a difference," says Vera.

Many trips to eye specialists later, she was diagnosed with chronic blepharitis, an inflammation of the eyelid, of unknown cause. And, after trial and error with different treatments, she now has a routine that keeps her discomfort and pain in check. However, some days her eyes flare up for no apparent reason: "I just wish I knew why I keep getting this," she says.

It may be difficult to pin Vera's symptoms to global warming, but scientists all over the world agree that increased levels of ultraviolet radiation reaching the surface of the Earth, resulting from ozone depletion at high altitude, and a toxic mix of air pollutants are responsible for serious eye disorders.

According to the World Health Organisation (WHO), of the 18 million people worldwide who have cataract-related diseases, 5% are directly attributable to UV radiation. UVA light, a component of UV radiation, stimulates the over-production of damaging oxygen-free radicals responsible for the clouding of the lens, typical of cataracts.

Last year researchers at the All India Institute of Medical Sciences, New Delhi, started gathering data for what is to date the largest study into the link between global warming and eye health.
More than 5,000 people across north-east India are being screened for eye disease and are asked to fill in a questionnaire on how much time they spend outdoors. The results will then be compared with regional meteorological data.

According to Robyn Lucas, associate professor at the Australian National University, Canberra, there is already strong evidence that short exposures to intense UV radiation can cause painful inflammation of the cornea and conjunctiva, and that even low-dose, long-term exposure is a risk factor for cataract pterygium - a non-cancerous growth of the thin tissue that lays over the white part of the eye - and eye cancer.

Scientists also believe that the rise in global temperature attributed to the greenhouse effect of global warming can be linked directly to some eye conditions, and that airborne pollutants, such as sulphur dioxide, soot and dust, can cause dry eyes, irritation and visual impairment.

Sonal Rughani, eye health development adviser at the Royal National Institute of Blind People (RNIB), says that excessive UV exposure can also increase the risk of age-related macular degeneration which affects the retina of the eye, causing blurry and distorted vision. Elderly people are most at risk.

Grass, soil, water, beach sand and sea foam can reflect up to 25% of the sun's rays, adding to the overall UV exposure, warns the WHO. For people who spend lots of time outdoors, particularly in the summer months, the RNIB recommends wearing sunglasses, glasses or contact lenses with a built-in UV filter that have a CE mark or carry British Standard BSEN 1836:1997.

Som Prasad, consultant ophthalmologist based in Wirral, also suggests using eye drops to combat dry eyes and wearing wide-brimmed hats that shield the eyes from sun glare.




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