Health of the Eyes and Computer Use.

September 14, 2009


Sharon welcomed the listeners and talked about the importance of water in life and life in water. She said that it is imperative for everyone to realize the importance of water, to drink plenty of water and to carry water with them if they are unsure of a water source. Dehydration, or lack of water, is out of control in our world and causes or contributes to ailments from allergies to obesity.

Guest: Larry Wan, DO

Larry Wan, DO, (San Jose, CA). "Health of the Eyes and Computer Use."

Larry Wan has been an optometrist for 25 years and since his office is in the heart of Silicon Valley, he has a special interest in vision and computers. Computers are a major cause of eye strain and dry eye, and the problem is getting worse.

The primary effect of computers is to retard the normal reflexive blink rate. Most people blink around 30 times a minute, or 10,000 times a day. During intense computer use this can drop to as little as five times a minute. Each blink replenishes the moisture in the eye's tear film and prolonged periods of insufficient blinking can cause the tear film to dehydrate.

Dry states (such as Arizona) are worse than humid states for dry eye caused by computers, and indoor conditions can be even worse on the eyes than outdoor dryness. In an effort to make building more energy efficient, designers have made them less livable. Forced-air heating and cooling, and insulated walls and windows are extremely dehydrating. Airliners are even worse for your eyes because of low humidity, recirculated air and crowding.

We want and need computers but we must also learn to live with them without endangering our health.

One problem with computers is that they are a different distance from the eyes than books, so glasses might need to be changed to accommodate this. Also, a computer image consists of thousands of dots (pixels), to which the eye must constantly adjust to keep the images in focus. In a book, the eyes mostly look at sharp, black and white lines. As a result, when working on a computer, the ciliary muscles in the eye that keeps things in focus are working constantly, which can be very tiring. While reading, they work far less.

Regarding the connection between the eyes, the brain, early visual development and stress, Dr. Wan noted a study indicating that 30 to 40 percent of the prison population has vision problems, most of which had gone undiagnosed. Dr. Wan recommends eye checkups at birth, three months, one year, two years and five years.

To prevent computer eye strain and computer caused dry eye, Dr. Wan suggests good lighting, the correct eyeglasses, good posture (to prevent shoulder and headaches), good lighting (not fluorescent), minimized glare, and positioning yourself to look down on the screen. The screen should be slightly more than an arm's length away. He recommends a flat panel rather than a tube screen.

Also, follow the "20/20"rule - take a 20 second break every 20 minutes in which you look away from the screen.

And don't forget to configure you computers so that children can also use them comfortably, especially with respect to the "arm's length" rule.

Dr. Wan's website is

Categories: Eye care and dry eye; health and wellness; 2009