The researchers examined more than 10,000 workers at several facilities in the electronics and steel industries. Participants were asked about ocular health and general health, and researchers noted how many hours per day they used a computer and for how many years.
Workers who had used a computer for less than 5 years were assigned a 1, 5-10 years received a 2, 10-20 years received a 3, and more than 20 years received a 4. The mean daily time spent at the computer for the past 5 years was also divided into four categories and scored as follows: less than 1 hour per day = 1, 1-4 hours per day = 2, 4-8 hours per day = 3, and more than 8 hours per day = 4. The researchers then multiplied the number assigned to years with the number assigned to hours to determine if the worker was a light (1-3), moderate (4-8) or heavy computer user (9-16).
The findings, published in the Journal of Epidemiology and Community Health, found that just over 5 percent of the employees were found to have vision abnormalities.
Workers who were classified as heavy computer users were more likely to be long-sighted (hypermetropia) or short-sighted (myopia). Around one-third of these workers had suspected glaucoma, and researchers noted a link between the cases of suspected glaucoma and short-sightedness.
The authors theorized that people suffering from myopia could be more susceptible to computer use-related eye strain.
"In the next decade, it might be important for public health professionals to show more concern about myopia and visual field abnormalities in heavy computer users," the researchers suggested.
David Wright, chief executive of the International Glaucoma Association, admitted there may be a risk in heavy use of computer equipment, adding, "It would be wise for anyone involved in such heavy usage to ensure that they receive regular comprehensive eye examinations in order to detect the earliest possible signs of the development of glaucoma when treatment is most effective."