The task will greatly influence comfort.  Here are some example of situations that usually increase user discomfort:

• Intense tasks such as games
• Tasks with few breaks from the screen
• Tasks which require constant looking from copy to screen such as data entry
• Detailed tasks such as desk top publishing or Computer Assisted Design (CAD)

The average rate of blinking is 12 to 15 times per minute. This is frequently reduced during intensive tasks leading to visual fatigue and dry eyes.  Therefore, reading from a screen reduces blinking which in turn, leads to discomfort.

Design is critical to comfort. Here is a short list of design factors that lead to greater discomfort:

• Eye level placement of screens causes eyes to be wide open causing faster drying.
• Eye level screens are too high for most bifocal wearers unless they have specially designed glasses for this task.
• Many glasses exacerbate the restriction of movement which is a consequence of most computer tasks causing neck, shoulder, and arm problems

What proportion of your patients have problems related to screen-based reading and computer use?

Most computer users who use the instrument for extended periods of time complain of visual fatigue and/or blurring.

What are the prolonged effects of reading from a screen versus other printed mediums?

There is no evidence of physical damage to the eyes due to prolonged reading from a computer screen. However, it has been demonstrated that most individuals do not read as quickly or as efficiently from a monitor in comparison to reading hard copy.

What are the most common visual problems of computer users?

The most common complaints are the following:

• dry eyes
• eye strain
• blurring

These complaints are often associated with headaches and neck and arm discomfort.

How does animation or movement affect reading and eye strain?

Patients with whom I deal have not spent sufficient time with animation for it to a significant issue. Many patients are uncomfortable with scrolling on the screen and generally handle it through avoidance. This is similar to other motion problems and is related to eye teaming problems and dysfunctions of visual integration with other movement and balance sensing systems such as the inner ear.

Solving the Problems Users Face

What things can a computer user do to minimize eye discomfort?

1. Take breaks.
2. Place the screen further away since eye strain tends to increase as tasks are closer.
3. Design the workstation to place the screen at least a few inches below eye level and eliminate reflections from the screen.
4. Do not have the screen excessively bright.
5. Have moderate background ambient illumination with supplemental task lighting for hard copy documents. Ideally the illumination from the screen should closely match the light reflected from the document.
6. Use a copy holder to place documents so they are at the same distance from the users eyes as the monitor.
7. Place hard copies in a plane parallel to the plane of the user's head to minimize reflections, maximize legibility of print, and keep the whole document the same distance from the user's eyes.
8. Have properly designed lenses for the task
9. Use supplementary eye lubricants as indicated

Do screen shields or screen filters work?

There are basically two types of shields to place over computer screens to reduce glare.  The less expensive type are a type of mesh which does reduce reflections but also reduces the quality of the print on the screen and are not recommended. The second is a polarized screen which reduces reflections without degrading the image. It does reduce illumination but this is not a problem.

What should computer users look for when seeking optometric services and advice?

For the examining doctor to be able to solve the patient's computer-related problems, the doctor must ask the appropriate questions about associated symptoms, design of the computer work station, and the nature and duration of the computer application. Tests then need to be done to  prescribe optimally for the distances used (or the new distances being used based on changes made as a result of the doctor's recommendations).   Lenses may need to be specifically designed for this task and may take the form of single power lenses, bifocal lenses, trifocal lenses, or progressive addition lenses.

Are there special glasses available for computer users?  Are there special tints and coatings available to minimize strain?

There are certain tints which can make some individuals more comfortable under fluorescent illumination. Although tints have been touted for computer users they are not as effective as modifying the colors on the screen and its brightness. Anti-reflection coated lenses do not eliminate reflections from the screen but do reduce reflections off the spectacle lenses and make many individuals more comfortable in a variety of visual environments. Spectacles should be individually designed to enable the operator to focus effortlessly on the screen with their normal head position (without having to raise their chin).  The lenses also need to enable the operator to see the keyboard and to read copy. Lenses should be minimally restrictive to head movement to avoid occupational diseases which result from lack of movement, repetitive movement, and unnatural postures.

How far should a computer user sit from a screen?

Operator distance from the monitor will vary with the height of the operator, the size of the screen, and the font on the screen. Monitors should not be closer than 18" and will be generally more comfortable if they are 24" to 30" away.

What fonts should software programmers and Web page designers use to improve users' reading?

In general, readability and comfort will be increased when fonts style and design are plain and are closest to those used in hard copy text. Excessively long lines of print, reduced spacing between lines, and bold colors all tend to interfere. Movement and flashing are very distracting to most individuals and are extremely stressful to a significant percentage of the population. Reading across a distracting background reduces the readers ability to easily absorb the message in the text.

Are there exercises available to decrease eye strain and visual problems?

The easiest effective exercise is to look away from the screen periodically at objects in the distance.  (This would best be done by getting away from the work station). Eye movements are relatively restricted while working at the computer (as are other body movements).  Looking around and doing purposeful ocular calisthenics (looking far to the right, left, up, down, and in the four corners) can help prevent and relieve eye strain from computer use. People with habitual eye strain and fatigue associated with computer use may have eye teaming and/or focusing dysfunctions which require individually prescribed vision therapy by a doctor who specializes in this area of vision care.

How often should a computer user take a break from the monitor?

Computer users need to take breaks to avoid visual fatigue, not to try to recover from fatigue. This is analogous to strenuous physical exercise such as shoveling snow. If one waits until one is exhausted before taking a break, minimal recovery takes place. If one takes a break before there is excessive fatigue, recovery is fairly rapid and essentially complete. Depending on the individual and the task, breaks should be taken every 30 to 60 minutes.