Vision After Forty: Normal healthy young eyes are able to focus from very far away to very close. Muscles within the eye have the ability to change the shape of the lens, and by doing so, change the focus. By the mid forties the lens loses some of it’s flexibility and focusing up close becomes difficult. This is normal and is called Presbyopia.

Prevention

Eyes and Computers

Using Your Eyes and Your Computer

It's 11:30 in the morning. You've been working at your computer since 9:00 AM. Your eyes feel irritated and fatigued, your vision is blurry and you still have several hours of work ahead of you.

The symptoms that you are experiencing are common among people who work with computers. They may be a result of the way that you use the equipment and furnishings in your workstation. But they may also be, at least partly, the result of a vision problem. Anytime you experience symptoms like headaches, eye strain, blurred vision, eye irritation, double vision, excessive tears or dry eyes, pain in the eyes or excessive blinking or squinting, you should visit your Doctor of Optometry for a comprehensive eye examination. And, when you do, be sure to tell the Doctor about the computer work that you do.

After you have had a comprehensive eye examination, there are a number of things that you can do to arrange and use the elements of your workstation to eliminate or minimize discomfort.

Adjusting your chair

Many times, your chair can be adjusted to make your work station much more efficient and comfortable. For instance:

  • Your feet should be flat on the floor (or on a slightly angled foot rest) with your knees bent close to or greater than 90 degrees.
  • Your chair should support your legs without excessive pressure on the back of your thighs.
  • Your back should be snug against the seat to fit your spinal contour.
  • Your thigh to trunk angle should be 90 degrees or greater.
  • The distance from the front of your chair to the hollow of your knee should be 2" (5 cm) to 4" ( 10 cm).
  • Your wrist and hand should extend nearly straight from the elbow to the home row of the keyboard.

Setting up your work surface

Consider the following suggestions to make sure the height of your work surface and the amount of leg room it provides are "comfortable."

  • For most people, the amount of leg room below the work surface should be about 25" (63.5 cm) high by 27" (68.6 cm) deep. Larger people will require more space.
  • A commonly preferred work surface height for a monitor is about 26" (66 cm) as opposed to conventional 29" (73.7 cm) of most tables or desks.

Keyboard

The following suggestions will help you arrange your monitor and your keyboard to allow you to work most productively and comfortably:

  • Locate your monitor 16" (40.6 cm) to 30" (76 cm) from your eyes, depending on the size of your display and your individual vision conditions. Many people find 20" (50.8 cm) to 26" (66 cm) most comfortable.
  • The top of the screen should be slightly below a horizontal eye level. Tilt the top of the monitor away from you at a 10 degree to 20 degree angle.
  • Place document holders close to your screen within the same viewing distance, this way you are not adjusting your focal distance which causes eye fatigue. Keep your keyboard and monitor in line.
  • Keep your screen free of fingerprints and dust. Both can reduce clarity.
  • Adjust your keyboard so it does not lie flat.

Monitors and lighting

To improve visual efficiency when using your computer:

  • Try to match the brightness of the surroundings to that of the screen. Overall room light should be about 20 to 70 foot candles, which is about half the level of normal office light.
  • The contrast between the characters on the screen and the screen background should be high.
  • Minimize reflected glare on your screen by using window treatments, dimmer switches on lights and anti-glare screens.
  • Position your screen perpendicular to windows or other bright light sources to reduce the likelihood of glare. To locate the source of glare, turn off the monitor to reveal the darkened screen. You should not be able to see any light bulbs or windows reflected in the screen. Move your monitor or tilt and swivel your screen to fix the problem.

The 20-20-20 Rule

When people are doing near vision tasks, such as looking at a monitor, they tend to blink less often. This can result in decreased tear production which leads to dryness of the cornea. A dry cornea will result in blurred vision and irritation of the eyes. To prevent this, follow the 20-20-20 rule. Every 20 minutes, take an eye break and look 20 feet away for 20 seconds. This will give you a chance to blink and produce some tears and will give your eye muscles a chance to relax.

Working efficiently

Human eyes were made for most efficient operation at a distance, but if you use the suggestions made here and those made by your Doctor of Optometry, you will be able to use your computer more comfortably and productively.