Heavy computer use increases glaucoma risk

Nearsighted workers even more susceptible

People who spend lots of time in front of computers — especially those who are myopic (nearsighted) — have a higher risk of developing glaucoma, a recent study suggested.1

"The optic nerve in myopic eyes might be structurally much more susceptible to computer stress than in nonmyopic eyes," explained lead author Masayuki Tatemichi, a professor of environmental and occupational health at Toho University School of Medicine in Tokyo. Tatemichi’s report on the study of more than 10,000 office workers appears in the Journal of Epidemiology and Community Health.

Almost everyone in the study who suffered computer-related eye damage was nearsighted, leading researchers to conclude excessive computer use poses the greatest risk to the myopic. Participants worked at jobs that required them to stare at computer screens for up to nine hours or more every day. OSHA reports up to 1 million cases of work-related eye injury each year; some, but not all, are related to computer use, according to OSHA. (See table for suggestions on easing computer-related eyestrain.)

Table: Alleviating Eye Stress from Computer Use
  • Choose a monitor that tilts or swivels, and has both contrast and brightness controls.
  • Arrange workstations and lighting to avoid reflected glare on the display screen or surrounding surfaces.
  • Reorient the workstation so bright lights from open windows are at right angles with the computer screen.
  • Set the computer monitor for dark characters on a light background; they are less affected by reflections than are light characters on a dark background.
  • Sit about 20 inches from the computer monitor, a little farther away than reading distance, with the top of the screen at or below eye level.
  • Adjust monitor angle and/or lighting to reduce neck/eye strain; adjust screen intensity for sharper images.
  • Place your screen and document holder at the same distance from the eye to avoid frequent refocusing and movement of the neck or back.
  • Take periodic rest breaks, and try to blink often to keep your eyes from drying out.

Source: OSHA, Washington, DC; American Academy of Ophthalmology, San Francisco.

Glaucoma causes a buildup of pressure inside the eye. The pressure damages blood vessels supplying the optic nerve, leading to vision loss.

Study participants filled out a questionnaire about computer use and, during an annual work-sponsored medical checkup, underwent additional ophthalmologic tests. About 5% of the workers had visual-field abnormalities. Further testing revealed that about one-third of those suffered from glaucoma. While people with glaucoma tend to be older, those in the Japanese study tended to be men younger than 40 who were heavy computer users. More than 95% also were myopic.

Researchers also noted some Japanese people develop glaucoma even though they have normal ocular pressure (which is virtually unheard of in Caucasians), so they may be more susceptible to glaucoma.

Tatemichi reports that the study results indicate a computer-dependent workforce could see a drastic uptick in glaucoma rates, and urges physicians to check for glaucoma in patients previously considered too young to be at risk.

No single test provides a glaucoma diagnosis. In this study, researchers used a method called frequency-doubling technology perimetry, coupled with a physical eye exam by an ophthalmologist. In the study, about 26% of employees were classified as light computer users, staring at screens for fewer than three hours a day on average over five years. Another 52% were moderate users, working at computer monitors for three to nine hours daily. The remaining 22% were heavy users who spent in excess of nine hours daily at the computer.

Tatemichi reports that one shortcoming of the study is that daily computer use is a crude measure, because certain uses of computers may cause significantly more eye strain. He suggests a need to more accurately gauge computer stress.

Reference

1. Tatemichi M, et al. Possible association between heavy computer users and glaucomatous visual field abnormalities: A cross-sectional study in Japanese workers. J Epidemiol Community Health 2004; 58:1,021-1,027.