Nowadays ours eyes do not get adequate rest as most of the time we are either on our computer, laptop, i-pad, mobile or watching television. Eye strain caused by excessive use of computer is called Computer Vision Syndrome or digital vision syndrome. It manifests as tiredness, inability to work for long hours, blurring of vision, double vision, watering, redness, itching and pain in eyes. These symptoms will be present in 95 per cent of people who use the computer for more than three hours a day.
Why It Happens
When we work on computers our muscles of convergence and accommodation have to work constantly causing their fatigue. Dryness caused by evaporation of tears and reflections from the computer screen coupled with bad posture further aggravate the symptoms.
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Posture and Exercises
Good posture and regular exercises of back and cervical muscles are a must if you use the computer for more than three to four hours a day.
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Lighting
The room should be well illuminated with the light source positioned in a way that light does not fall directly on your eyes or on the screen The light source should be behind the screen or on the ceiling and partially covered. anti-glare screens and spectacles can also help.
Dryness
Normally we blink 10 to 12 times a minute. When we watch TV our blink rate is 5 to 6 a minute and while working on the computer it further goes down to 3 to 4 times a minute. Reduced blinking causes evaporation of tears thereby increasing the osmolarity (concentration) of the tears. The hyperosmolar tears induce inflammation and tear film instability which in turn cause increase reflex lacrimation. In other words, the dry eye caused by Computer Vision Syndrome may present not only as dry eye but may present as watering and inflamed eye.
To overcome this, it is better to have the computer screen 20 to 40 degrees below the eye level. This causes partial closure of the eyes by the lids thereby decreasing the evaporative surface
One has to make a conscious effort to increase the blinking or even better would be to close the eyes completely in between, and then open them, so that tears are uniformly spread on the eye and hyperosmolar tears are drained out.
Preservative free tear substitute have a soothing effect by restoring the osmolarity of tears and decreasing their evaporation. They can be used 2 to 4 times a day safely, without any side effects. If symptoms are not relieved or if there is excessive watering and inflammation one may need a short course of steroid eye drops. These should never be self medicated because they cause an increased risk of eye threatening complications like corneal infections, cataract and glaucoma. However, their use is absolutely safe under the supervision of the eye surgeon. Optometrist or shop owner should not prescribe them because they are not capable of early detection and management of the complications of steroid eye drops.
Relaxing Accommodation
Rule of 20:20:20
Every 20 minute look at 20 feet for 20 seconds
When you look at a near object, the ciliary muscles (muscles used to change the power of our natural lens) contract to change the power of the lens so as to focus on the screen. This constant focusing causes fatigue of ciliary muscles and you are not able to work for long hours. Sometimes these muscles go into spasm if they are not able to relax when you want to look for distance, thereby causing pseudomyopia and hazy vision for distance. Give rest to your muscle following rule of 20:20:20.
Relaxing Convergence
Rule of 60:40:20
Every 60 minutes, work for 40 minutes and relax for 20 minutes. If not possible then at least a 10 minute break is an absolute must every 60 minutes.
You need to get up from your table and walk around, move your spine, neck, legs and arms and try to look at infinity or as far as possible. One can also do palming of eyes. Rub your hands together for a few seconds and then place on closed eyes. One can also keep the eyes closed, sit straight and do deep breathing exercises.
Spectacle correction
This is probably the most important part of the management of computer vision syndrome. If you want to go for a long walk, I am sure that you would like to wear comfortable sports shoes. In the same way, while we are using our eyes for long hours, we should wear the absolutely correct spectacle prescription. Even a small error of just 0.25 D in the prescription may aggravate the symptoms manifolds.
A correct spectacle prescription is not possible without relaxing your ciliary muscles. In other words, refraction has to be done under cyclopegic-mydriatic drops. This can only be done by eye surgeon, not by optical shop or optometrist. Many a times you don’t need spectacles for seeing but you need to use them for preventing eye strain. The correct prescription will go a long way in relaxing your eyes and decreasing your discomfort.
(The writer is a seasoned ophthalmologist and co-chairman department of ophthalmology, Sir Ganga Ram Hospital, New Delhi).