If you've ever come home from work with blurred vision and a headache, it may be because of fluorescent lighting. Fluorescent lights are much brighter than traditional incandescent bulbs, but this isn't always a good thing. According to the American National Standards Institute, most offices flood computer workstations with 2 to 5 times as much light as they need, causing eye strain and fatigue.
When you flip the switch of a fluorescent light, electricity excites the gas in the bulb, causing it to give off ultraviolet light. Once that light passes through the white coating on the inside of the bulb, it's visible to the human eye. As long as the electricity is on, however, that light will grow brighter and brighter. To avoid over-bright light, fluorescent lights come with an electrical component that regulates the electricity coming into the light. This component, called a "ballast," keeps the glow steady.
Some fluorescent lights flicker as they warm up because the ballast has yet to produce the right amount of electricity to power the bulb. Once the bulb is warmed up, the flicker is supposed to disappear. According to the Canadian Centre for Occupational Health and Safety, however, some people can still sense the flickering of fluorescent lights as the ballast regulates electricity flow through the bulb. Anytime the voltage flowing through the bulb changes, the light flickers. In places such as schools and office buildings, where fluorescent light use is common, other power functions, such as heating and air conditioning, can cause voltage changes and flickering. It's this strobe-like flickering effect that can cause eye strain.
Symptoms of Eye Strain
People with eye strain experience burning eyes, watery eyes, blurred vision, and an increased sensitivity to light that can cause headaches. If you're sitting in front of a computer for hours a day, eye strain can get even worse. Your eyes may blur when you glance from your monitor to papers on your desk, or you may experience color burn---seeing the colors displayed on your monitor for a second after you look away from the source.
Avoiding Eye Strain
Eye strain will usually go away once you remove the source of the strain. The Division of Occupational Health and Safety recommends performing periodic eye exercises such as blinking, cupping your hands over your eyes and breathing deeply, and working on up-and-down and left-to-right eye movements with your lids closed.
Fluorescent bulbs with high-frequency electronic ballasts instead of older magnetic ballasts tend to produce less eyestrain. They convert electricity into a high-frequency voltage which, even when it flickers, is so fast that it's invisible to the human eye. Replacing old fluorescent bulbs with newer, more efficient electronic-ballast bulbs is one of the best ways to fight eyestrain. Because workstations are often over-lit from above, closing drapes and blinds can help reduce the glare that contributes to eyestrain. Your computer monitor should face windows or task lamps at a 90-degree angle. If possible, use a glare screen or lay paperwork over your monitor so that it overhangs by approximately 2 inches, cutting glare from overhead fluorescent lighting.
- GE Consumer and Industrial Lighting: Ballasts and Fluorescent Tubes
- GE Consumer and Industrial Lighting: Compact Fluorescent Light Bulbs
- Canadian Centre for Occupational Health and Safety: Light Flicker
- Mayo Clinic: Eyestrain
- Division of Occupational Health and Safety: Ergonomics for Computer Workstations