Staring at hard facts

Spending hours staring at a computer screen may raise the risk of glaucoma, a progressive eye disease that can lead to blindness, some scientists believe.

The discovery contradicts years of advice which suggested that gazing at computers did not damage the optic nerve. Researchers aim to replicate the study to confirm the findings.

The results emerged from a study in Japan of 10,000 workers with an average age of 43. It found a statistical link between heavy computer use and eye problems that presage glaucoma. The problems were more common among staff with existing vision defects, such as short-sight or long-sight.

The team said there could be a major rise in the number of glaucoma cases if action was not taken to check people who spend a long time in front of a screen and who already have eye conditions.

"Computer stress is reaching higher levels than have ever been experienced before," the team from the Toho University School of Medicine in Tokyo said.

"In the next decade it might be important for public health professionals to show more concern about myopia [short-sightedness] and visual field abnormalities in heavy computer users."

Visual field abnormalities are distortions or gaps in the field of view.

"Myopic workers with a history of long-term computer use might have an increased risk of visual field abnormalities, possibly related to glaucoma," said Dr Masayuki Tatemichi, who led the team. The work was reported in the British Journal of Ophthalmology.

Glaucoma is more common in older people and comes about when the optic nerve is damaged, possibly by high pressure inside the eye. The causes are unknown, but potential risk factors include smoking and high blood pressure.

Previously, opticians discounted the possibility that computer use was linked to glaucoma and several studies had suggested that there was no connection between intensive computer use and glaucoma. Although poor computer screens can cause eye strain, that was not believed to be a precursor to the problem.

For men in offices, the findings are a second alarm bell over glaucoma. A study last year study suggested that wearing a tie too tightly could also lead to the disorder.

Toho University researchers found that 5.1 per cent of the workers had visual field abnormalities, which can be a precursor to more advanced glaucoma, which affects 0.74 per cent of the population. Further tests found that 32 per cent had suspected glaucoma. The researchers also found a statistical link with heavy computer use among short-sighted workers. They suggested that the optic nerve in short-sighted people might have a structural condition that rendered it more susceptible to computer stress than non-myopic eyes.

- INDEPENDENT

Keep your eye on safety

The Government's Occupational Safety and Health service has a brochure called How to use your visual display unit safely, available as a free download from the OSH website.

It says computer users tend to have a fixed posture that means the gaze distance to their computer monitor stays the same for long periods.

This means the eye muscles don't get much opportunity to move, which is the main reason for visual discomfort.

However, there may be other reasons why computer users suffer eye strain as a result of working in front of a screen all day.

These include:

* Lack of image clarity. The image could be out of focus because of an ageing or faulty monitor; the refresh rate may not be set correctly; or the colour may be poor.

* Glare from reflections and lights are other possible causes of eye problems.

* Concentrating on the work and not blinking can lead to problems or you just may need to have your sight tested and be prescribed glasses to correct your vision. Make sure you tell your optometrist if you work long hours at a computer screen.

* If you find that you are immobile while at the desk - staring at the screen - then try to get into the habit of taking micro-pauses. Look at a distant object for a moment every now and then. This will give your eyes some exercise as they focus on something different.

* Some computer users get problems because they don't blink often enough. Take a break away from the desk for 10 minutes every hour and ensure you have some thinking time away from the screen.

* Character quality on a computer screen is not as good as on paper. There is not much you can do about this except to make sure that the brightness and contrast of your screen are adjusted.

* As we get older our eyes lose their ability to see detail and focus on close objects. Computer work does not cause eye deterioration to happen any faster than it happens normally. However, working at a computer often shows up an eye defect such as short-sightedness.

See your supervisor about your company's policy on vision testing for computer users.

* Source: Occupation Health and Safety