Eye strain in the office
The use of computers amongst office workers has increased over the past two decades. This has resulted in an increase in health disorders associated with computer use, the most common of which are eye and vision problems. While eye health problems related to computer use are usually temporary, they cause significant discomfort to computer users and are mostly preventable.
Risk factors for vision problems associated with computer use
The main risk factors for developing eye or vision problems through computer use are:
· Viewing unclear images;
· Viewing images or characters on the screen which are too small;
· Using a screen which is glary or reflects other images;
· Working with background lighting which is too bright;
· Sitting an inappropriate distance from the screen (too close or too far);
· Looking at the computer screen for long periods of time, particularly without breaks; and
· Working in a stressful environment.
There now is a substantial amount of evidence that computer use is closely associated with various eye disorders, which is collectively referred to as computer vision syndrome (CVS). Temporary vision and eye problems which are associated with computer use include:
· Eye Strain or Fatigue
· Blurred Vision
· Burning, itching or tearing eyes
· Temporary change in ability to see colors
· Tired or irritated eyes.
Non-ocular symptoms such as headaches, shoulder, neck or back pain may also result from over-correction or accommodation postures that aim to reduce eye strain (e.g. bending forward to view the screen more clearly.
Available evidence also suggests that there is an increased risk of open-angle glaucoma associated with regular computer use for extended periods. One study reported that individuals who had used a computer for an average of 4-8 hours per day over five years were 1.14 times more likely to develop open-angle glaucoma than those who used computers for less than 4 hours per day, while those who averaged more than 8 hours in front of a computer each day were 1.38 times more likely to develop glaucoma. The risk of developing glaucoma was even greater amongst participants with co-existing refractive errors.
Preventing eye health problems related to computer use
There are many measures which individuals or employers can take to reduce the risk of workers developing eye problems as a result of computer use.
Use an appropriate computer screen
Use a large, clean screen with a flat surface. The user should also ensure their screen has easily adjustable contrast and brightness and that images displayed on the screen are in sharp, in clear focus and does not flicker.
Work station ergonomics
The most important ergonomic factor for eye strain is the distance of the eyes from the computer screen. Computer users should arrange their workstation so that the computer screen is 18-30 inches from their eyes. In addition computer users should take measures to reduce glare on their screen. Ergonomic measures which can reduce glare include placing computer screens at a 90o angle to windows (they should never be placed directly in front of or behind a window) and to the side, rather than directly below light sources.
Glare and reflection
It is also important to take measures to prevent glare, shadow and reflection caused by external sources of light, as these can contribute to eye strain. Glare results when there is a high level of contrast between the intensity of light in the foreground and background, for example, if a bright window is positioned behind a computer screen.
In glary conditions, the eyes have to constantly adapt to the difference in contrast between dark and light areas, resulting in eye fatigue, headaches and reduced visibility. Glare can also be reflected from a computer screen and contribute to eye strain.
Ways to reduce direct or reflected glare in the office environment include:
· Control natural light from windows through the use of curtains, blinds or window tinting
· Reduce the contrast between foreground and background
· Reposition the workstation or light source to adjust light falling directly on the work surface
· Adjust the intensity of general lighting to suit the task being performed
· Choose office furniture in neutral or dark colors which will reduce glare and reflection
· Change the type of lighting
· Use anti-glare screen filters
Intensity of lighting
Good lighting should allow people to easily view their work without the need to strain the eyes. The type of work being performed will determine the intensity of light required. Work typically performed in an office environment, which involves fine and detailed work such as reading and writing, requires much more intense lighting than tasks which do not involve detailed viewing. While lights need to be bright enough to ensure detailed viewing tasks can be performed without straining the eyes, they should not be so bright as to cause glare and reflection.
Office lighting that is too bright or not bright enough increases the risk of workers developing eye health problems. Computer users should be working in rooms in which the brightness is between 200-500lux. Flickering lights from old or malfunctioning fluorescent tubes should be replaced or regularly maintained.
Take regular breaks from computer use
Users should take regular breaks from looking at their computer screen to allow the eyes to recover and focus on distant objects. Clinical optometrists often suggest the 20/20/20 rule, that is, after 20 minutes of computer use; look at something 20 feet away for at least 20 seconds.
It is also recommended that computer users periodically take 15 minute breaks every 2 hours of computer use, to prevent eye problems and muscular skeletal disorders. Computer users engaged in intensive keyboard work should take a 15 minute break every hour.
Computer users should also take a few minutes to perform simple eye exercises every hour.
Wear glasses not contact lenses
The use of contact lenses increases the severity of symptoms of dry-eye syndrome. This syndrome is a common eye condition, with research indicating that up to 48% of office workers experience dry eyes. Office workers who wear contact lenses experience more severe symptoms of dry eye because contact lenses can cause friction if the eye is not well lubricated. If the surface of the eye is dry, the contact lens also becomes dry and sticks to the upper eyelid during blinking. This “friction effect” from dry eye is what produces the discomfort.
Prevent dry eyes
Further measures which can be taken to prevent the eyes from becoming dry include:
· Use lubricants or artificial tears up to 4 times a day
· Lower the position of the monitor so that more of the eye surface is covered by the eyelid because it is looking downwards
· Increase blinking
· Drink 6-8 glasses of water per day to ensure adequate hydration.
Take a yearly vision test
Regular computer users should take a yearly vision test so that any eye problems can be discussed with an eye professional, eye problems identified early and preventative strategies developed. It is important that patients tell their health practitioner that they are a computer user, as this may impact on the type of lenses prescribed if correction is needed.