Reprinted from The RSI Network - Issue 24 - Aug'95
VDT users report more musculoskeletal pain as the brightness level of overhead lights
increases, according to a new study by Dr. James Sheedy and Ian Bailey of the University
of California's School of Optometry, Berkeley. More predictably, subjects also experience
more visual discomfort and eyestrain at higher luminance levels. "We were surprised
that musculoskeletal symptoms were related to glare," Sheedy said. "One idea is
that glare might cause people to change their posture or tense their muscles."
While it is known that bright lights in easy view of a VDT operator cause eyestrain,
overhead glare had not been well studied before, Sheedy said. "Indirect lighting may
be better for VDT users," he said. The study was presented at the "Work with
Display Units '94" [October] conference in Milan [Italy] and has been submitted for
publication. The research was funded by a grant from Peerless Lighting Corp. in Berkeley.
The researchers asked 30 subjects to read Sherlock Holmes stories on computer monitors.
To change the brightness of the overhead light without changing the light on the work
area, the subjects wore headbands with clear, gray, or opaque visors. The lights were 45
degrees to 90 degrees from their line of sight. Some of the subjects reported
significantly more symptoms than others, indicating that certain people may be more
sensitive to lighting conditions, Sheedy said. Among those who had more symptoms, there
was a statistically significant increase in tired and sore eyes and back, neck and
shoulder pain at higher brightness levels. Symptoms increased for all subjects the longer
they read.
Reprinted with permission of VDT NEWS, based in New York, NY. The article first
appeared in the November/December 1994 issue of VDT NEWS.
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