Computer And Yor Eyes
Computer-eye interactions put a heavy demand on our visual system, which was developed over centuries to serve man as "the hunter." Only in the last century has man begun to rely on his reading vision for his survival. Heavy loads of close reading or computer work can induce "distress".
Symptoms include: eyestrain, headaches, itching and burning, scratchy sensation, blurred vision, doubling of vision and color perception changes. Indirect symptoms can be: neck, shoulder, back and wrist pains, fatigue and general stress, leading to lower job performance and decreased visual efficiency.
A report prepared by the National Academy of Science suggests that simply improving the ergonomic condition of the worker could reduce vision complaints by up to 39% . The computer work environment consists of many different factors that can be controlled, including; lighting, user position, computer placement, noise and air quality
- Computer System
The VDT, Video Display Terminal, is unlike a book on your lap, rather its placed straight in front of the user, making it more susceptible to visual interference, such as; glare, distracting background objects and room light intensity variations, where a mirror effect can occur. The "straight ahead" screen puts different eye muscles to work, leading to visual stress.
The contrast on the screen is very important. A dimly lit work environment works best. The eye has less adjusting to do, when shifting back and forth from the low light intensity of the computer screen to the varying brightness of the room. Use a desk lamp to provide light for the printed text. Avoid getting glare from the lamp on the screen.
Screen colors are important. Avoid red and blue screen characters. Ideal colors are in the middle of the light spectrum. Use green, yellow and orange characters. Choose a color that feels comfortable to look at. Most screens use light print on a dark background (opposite what you see in a book black on white background).
Research is inconclusive about what is better. Try both ways to see which feels better, varying throughout the day. Adjust the screen brightness and contrast for maximum comfort. The character size should be 2.5-3.0mm and in sharp focus. The resolution of the print depends on the dot matrix dimensions; 7 x 9 is best; 9 x 11 is better. The font type should be easy to see at a glance
Check your VDT every 6 months to see that it is operating at the manufacturer's specifications. Look at the manufacturer's guide on how to make periodic inspections. This will maintain text character quality. Screen filters help eliminate glare and static. Filters with polarizing properties trap light reflected from the computer screen and enhance screen contrast.
Be sure your filter doesn't make the screen darker and reduce the character readability. Static and dust on the screen need to be cleaned daily with an anti-static spray or cloth. Cover the terminal at night. The best filters are, of course, the most expensive.
A VDT visor is an economical way to reduce glare and reflections. Use a detachable keyboard, in order to be placed in a comfortable position.
- Computer Work Station
Computer Working Distance: Recommend: 20 inches (50 centimeters) The line of sight to the top of the screen: Recommend 20 degrees below horizontal. The line of sight to the bottom of the screen: Recommend 40 degrees below horizontal.
Manuscript Holder: Recommend text to be at the same level as the display screen, thus at same eye level as the ” VDT TERMINAL SPECTACLES”, recommend special glasses as prescribed for the patient by their doctor to suit the needs of the patient
Computer Furniture and Work Space Design: Avoid chairs that are awkward and uncomfortable when trying to see the screen or use the keyboard. Use an adjustable pneumatic chair with back (lumbar) support. A swivel chair with a sturdy base on coasters is good. The VDT should have a tilt and swivel base. This helps control the glare and screen reflections. A document holder is needed to hold the text at the same distance and height of the screen. The document holder can be placed between the keyboard and the screen to control your work space and gain comfort, functionality and privacy; this enhances your efficiency. Consult computer catalogues to see what might work well at your station.
Eliminate glare from overhead light and windows. Rotate the screen away from the glare. Use filters, but watch out for any loss of screen contrast. Set the room temperature so you are "comfortable". Try to get some fresh air into your space. Reduce room illumination by trying to get a dimmer switch, to regulate the light. The room light should be 3 times brighter than the VDT screen background. Use a desk lamp to see your text. Paint the room walls in a flat matte finish or pastel colors. Position your desk so you can look up and see across the room or out the window. Get up and walk around and look far away on your breaks. Keep your work area "quiet." Cover a high impact printer to cut down on noise.
- Computer User
Use Artificial Tears throughout the Day
Moisturize your eyes from the dry air. Do complete blinks while waiting for your screen displays to change. We tend not to blink when doing visually demanding tasks.
BLINK 6-15 times per minute. Drink 6-8 glasses of water per day. Use artificial tears to rewet your eyes and contact lenses. Re-clean your lenses after lunch.
These are prescribed according to your visual system functions, your age and the distance of your eyes from the computer screen (MEASURE IT!). Consider these as a part of your work attire, an “occupational tool" like a welder would consider his special safety filter glasses. OVER FORTY? Get computer bifocals (top lens for the screen, bottom lens for seeing printed text) or computer trifocals or Pal’s progressive addition lenses (invisible bifocals).
Routine Vision Exams
As time flies, your eyes change. Get them checked!
Keep your feet on the floor. You may need a foot rest if you are short. Keep the trunk straight, but inclined forward slightly from the hips. Keep the wrist straight while typing. Don't rest your wrists on sharp edges. Keep the thighs horizontal and feet flat.
The upper arm should be straight vertically. The forearm should be horizontal or slightly lower than that while typing. Keep your legs from hitting the bottom of your desk.
After 20 minutes, pause look away from your computer and stare at an object in a distant for 20 seconds. On data entry: breaks; 10 minutes every hour. Get up and walk around or do some stretching while in your chair.
The National Institute of Occupational Safety and Health recommends taking a 15 minute alternate task break every hour if you are a full-time user.
The above information is general in nature and may not be applicable to each patient and their needs. Routine vision examinations are recommended.