Computer vision syndrome

Computer vision syndrome (CVS) is a temporary condition resulting from focusing the eyes on a computer display for protracted, uninterrupted periods of time. Some symptoms of CVS include headaches, blurred vision, neck pain, fatigue, eye strain, dry, irritated eyes, double vision, polyopia, and difficulty refocusing the eyes. These symptoms can be further aggravated by improper lighting conditions (ie. bright overhead lighting or glare) or air moving past the eyes (e.g. overhead vents, direct air from a fan).

Pathophysiology

CVS is caused by decreased blinking reflex while working long hours focusing on computer screens. The normal blink rate in human eyes is 16–20 per minute. Studies have shown that the blink rate decreases to as low as 6–8 blinks/minute for persons working on the computer screen. This leads to dry eyes. Also, the near focusing effort required for such long hours puts strain on ciliary muscles of the eye. This induces symptoms of asthenopia and leads to a feeling of tiredness in the eyes after long hours of work. Some patients present with inability to properly focus on near objects after a short duration. This can be seen in people aged around 30–40 years of age, leading to a decrease in the accommodative focusing mechanisms of the eye. This can be a setting for early presbyopia.

Prevalence

According to the National Institute of Occupational Safety and Health, computer vision syndrome affects some 90% of the people who spend three hours or more at day at a computer.

Therapy

Dry eye is a major symptom that is targeted in the therapy of CVS. The use of over-the-counter artificial-tear solutions can reduce the effects of dry eye in CVS.

Asthenopic symptoms in the eye are responsible for much of the morbidity in CVS. Proper rest to the eye and its muscles is recommended to relieve the associated eye strain. Various catch-phrases have been used to spread awareness about giving rest to the eyes while working on computers. A routinely recommended approach is to consciously blink the eyes every now and then (this helps replenish the tear film) and to look out the window to a distant object or to the sky—doing so provides rest to the ciliary muscles. One of the catch phrases is the "20-20-20 rule": every 20 minutes, focus the eyes on an object 20 feet (6 meters) away for 20 seconds. This basically gives a convenient distance and timeframe for a person to follow the advice from the optometrist and ophthalmologist. Otherwise, the patient is advised to close his/her eyes (which has a similar effect) for 20 seconds, at least every half hour.

Decreased focusing capability is mitigated by wearing a small plus-powered (+1.00 to +1.50) over-the-counter pair of eyeglasses. Wearing these eyeglasses helps such patients regain their ability to focus on near objects. People who are engaged in other occupations—such as tailors engaged in embroidery—can experience similar symptoms and can be helped by these glasses.

See also

• Asthenopia
• Photophobia
• Repetitive strain injury
• Presbyopia

External links

• AllAboutVision.com page on CVS
• The American Optometric Association's article on CVS
• Zheng Yan, Liang Hu, Hao Chen and Fan Lu: Computer Vision Syndrome: A widely spreading but largely unknown epidemic among computer users. Computers in Human Behavior, Volume 24, Issue 5, September 2008, Pages 2026-2042ko:VDT 증후군

zh:电脑视觉综合症