Computer Vision Syndrome, or CVS, is not an actual medical diagnosis, but a term used to describe negative symptoms associated with viewing digital screens such as computers, tablets and smart phones. CVS can present as tired eyes, dry eyes, tearing, blurred vision, eye pain, headaches and neck pain.
Tired eyes can result from staring at a computer screen for long periods of time. Our eyes have the ability to move quickly and to reset their focus, but when staring at a screen the muscles become fatigued from holding the same position too long. A good way to help prevent this is to follow the 20-20-20 rule; after every 20 minutes of screen time, look at least 20 feet away for at least 20 seconds. This allows the eye muscles to relax and can help prevent eye fatigue.
Another reason that eyes get tired is because looking at a bright screen can cause fatigue. I know if I’m driving for a while on a sunny day I start to feel drowsy. By adjusting the screen brightness and/or increasing the font size, reading can be more comfortable.
Regular and complete blinking is required to keep the eye surface moist. Irregularities in the tear film can cause blurred vision and discomfort. Digital device users blink less, which causes tear evaporation and dry spots on the cornea. Dry eyes can also result in reflex tearing, which can also blur vision. In addition, even the blinks themselves are frequently incomplete.
Videography has shown that during computer use, it is quite common to see the eyelid margins not contact each other during a blink, which results in incomplete spreading of the tear film across the surface. So, during your 20 second blink following the 20-20-20 rule, squeeze your eyes forcefully several times. This helps to express oil from the meibomian glands that empty along the eyelid margins, which function to maintain a smooth tear surface between blinks. People with pre-existing dry eyes often benefit from the use of artificial tears during the day.
Proper lighting is key to preventing some of the problems associated with CVS. Too much glare coming from a window beyond the computer screen, or too much light shining down from fluorescent bulbs, can cause the words on the screen to appear washed out, leading to squinting and eye strain, which can then lead to headaches. A glare screen which attaches to the monitor can help. It is important to make sure the monitor is at right angles to a window, or to have the shades drawn. Some recommend removing the center two fluorescent bulbs from the four bulb overhead fluorescent lights. I have even suggested a baseball cap with a brim to those who are in a cubicle type situation and don’t have much control over the overhead lighting. Lamps should provide light directly onto reading material, and not project light onto the screen or toward the user’s eyes.
Many people are concerned that the blue light emitted from digital screens is harmful to the eyes. While a July 2018 study in the journal Scientific Reports1demonstrated that retinal, a photoreceptor chemical in the retina, excited by blue light can irreversibly damage cell membranes, leading to cell death, the cells they studied were not derived from the retina, were not exposed to the amounts of blue light a person is normally exposed to, and the parts of the cells that were damaged are not normally in contact with retinal in a living person. Blue light is present in sunlight in higher amounts than digital screens, and there has been no evidence to show that it his harmful to the eyes2. You may have seen blue-blocking computer glasses advertised, purported to prevent damage from blue light and to maintain eye health. While the American Academy of Ophthalmology does not recommend any specific type of lens for computer use, blue-blocking lenses may make computer viewing more comfortable with less eye strain.
Blue light affects the circadian rhythm, which is why it is recommended to refrain from using digital screens 1-2 hours prior to bedtime so your body isn’t fooled into thinking it’s still daytime. Many devices have a “night mode”, which changes the background to a softer, darker color with lighter text, which can be easier on the eyes.
Finally, in addition to affecting your eyes, screens can also contribute to neck pain. This can occur when posture is improper at the computer, or from looking down and hunching the shoulders while looking at a tablet or phone. Proper posture is important for preventing tight muscles and neck and shoulder pain. OSHA (Occupational Health and Safety Association) recommends that computer monitors be placed at least 20 inches from the user’s eyes and be at or just below eye level. Chairs should have a backrest to support the lower back, a cushioned seat with rounded not sharp front edges, a height allowing the feet to rest comfortably flat on the floor, and armrests to support the forearms when using the keyboard. The proper glasses prescription should be worn; if trying to look at the computer through the reading portion of a bifocal, the chin goes up and the shoulders hunch, leading to upper body discomfort.
As I often remind my patients, humans didn’t evolve to sit in front of a computer screen or cell phone all day long. Our eyes are meant to dart around, watching for predators, hunting for prey, constantly moving. To make it through the day without tired, burning, strained eyes and headaches, pay attention to taking breaks, blinking frequently, maintaining good posture, and avoiding glare.
1. “Blue light excited retinal intercepts cellular signaling”; Scientific Reports July 5, 2018
2. American Academy of Ophthalmology website: https://www.aao.org/eye-health/news/smartphone-blue-light-is-not-blinding-you