The risk may be higher for heavy computer users who are also
short-sighted, says the report, compiled by a team of researchers
led by Dr Masayuki Tatemichi of Toho University School of
Medicine.
Glaucoma is a relatively common eye disease that develops very
slowly, characterised by progressive sight defects or visual field
abnormalities, as the disease damages the optic nerve over time.
Once damaged, the optic nerve cannot be repaired, but early
detection of the disease can limit further loss of vision.
Glaucoma most commonly affects people over the age of 60, and is
found in 2% of the population over the age of 40. A family history
of the disease increases the risk by a factor of four to nine
times. Its exact cause is unknown, although potential risk factors,
including smoking and high blood pressure, have been suggested.
Assessing the link between computer use and glaucoma, the
research team tested the sight of workers in four different
Japanese companies, employing over 5,000 people each.
In all, some 10,000 workers, with an average age of 43, were
randomly selected for testing as part of a general medical
check-up. They also completed questionnaires about their computer
use, both at home and at work, and any history of eye disease.
Computer use was categorised in blocks of five years, ranging
from less than five years to more than 20 years. The average amount
of time spent at the screen per session, ranging from one hour to
more than eight hours at a time, was also taken into account in
classifying participants as light, medium or heavy users. Those
classified as heavy users tended to be men and younger.
The test revealed that 522 (5.1%) employees had visual field
abnormalities, and there appeared to be a significant link between
these abnormalities and heavy computer use among those with either
long or short sight, collectively known as "refractive errors."
An in-depth eye test then revealed that around a third of these
workers (165) had suspected glaucoma, characterised by distinct
visual field abnormalities. There also appeared to be a significant
link between these and heavy computer use among workers who were
short sighted, said the report.
In fact, as the most common refractive error was
short-sightedness, the authors speculate that the optic nerve in
short-sighted eyes might be more vulnerable to computer stress than
it is in normal eyes. But the researchers recommend that further
study is needed before this conclusion can be confirmed, as short
sightedness is a recognised risk factor for glaucoma anyway.
"Computer stress is reaching higher levels than have ever been
experienced before. In the next decade, therefore, it might be
important for public health professionals to show more concern
about myopia and VFA [visual field abnormalities] in heavy computer
users," concludes the report.
