The increasing use of smaller work and recreational gadgets, such as PDAs, laptops and mobile phones, may be contributing to the visual fatigue and discomfort experienced by millions, it was claimed today.

"The unique characteristics and high visual demands of computer work and play make many individuals susceptible to the development of vision-related problems, " said Dr Jeffrey Anshel, a practicing optometrist and author of Visual Ergonomics in the Workplace.

"With the proliferation of portable electronic devices it is no surprise that eye care professionals are seeing more patients who complain of ocular discomfort."

A recent US survey of doctors of optometry found that more than 14 per cent of patients reported eye or vision-related symptoms resulting from computer work.

Staring at a computer monitor or the small screens on most devices can lead to a variety of ailments, including headaches, eyestrain, blurred vision, dry and irritated eyes, neck and/or backache, and sensitivity to light, Dr Anshel warned.

"Eye stress and strain may be caused by a combination of individual visual problems, improper viewing habits, and poor environmental conditions, such as glare, improper workstation set up, dirty screens, poor lighting and viewing angles," he said.

Dr Anshel has helped companies and government agencies, including Mitsubishi, American Airlines, 3M, and the US Department of Labour to address the high stress area of vision demands in relation to working with computer monitors.

"Uncorrected or under-corrected vision problems can be major contributing factors to computer-related eye stress, affecting visual performance and comf ort," he explained.

"The good news is that many potential eye and/or vision problems can be reduced or eliminated by the appropriate adjustment and placement of computer monitors, lighting control, good preventive vision care habits, and regular professional eye care."