COMPUTER VISION SYNDROME: AN UPDATE
1Pooja Bagdi*, 1Swati Rathore, 2Kamal Singh Rathore
1B.N. College of Pharmacy, Udaipur
2B.N. Girls College of Pharmacy, Udaipur-Raj.
+919828325713(M)
Vision is our most precious sense. Our eyes are in constant use every waking minute of every day. Vision disturbance is a silent enemy that only appears after a long period of continued stress.
INTRODUCTION
Computers have equalled the telephone is becoming the most indispensable piece of office equipment. Because computer use is such a high visually demanding task, vision problems and symptoms have become very common in today's workplace. Most studies indicate that computer operators, who view their Video Display Terminals (VDTs), report more eye-related problems than non-VDT office workers. A number of investigators have indicated that visual symptoms occur in 75-90% of VDT workers. In contrast to the popular conception regarding carpal tunnel syndrome, a study released by NIOSH showed that only 22% of VDT worker. A survey of optometrists indicated that 10 million eye examinations are annually given in this country primarily because of visual problems at VDTs. This study delineated the series of symptoms which eventually became known as Computer Vision Syndrome (CVS). Computer Vision Syndrome describes a group of eye and vision-related problems that result from prolonged computer use. Many individuals experience eye discomfort and vision problems when viewing a computer screen for extended periods. The level of discomfort appears to increase with the amount of computer use.
CAUSES OF COMPUTER VISION SYNDROME
Viewing a computer screen often makes the eyes work harder. As a result, the unique characteristics and high visual demands of computer viewing make many individuals susceptible to the development of vision-related symptoms. Uncorrected vision problems can increase the severity of Computer Vision Syndrome symptoms. Viewing a computer screen is different than reading a printed page. Often the letters on the computer screen are not as precise or sharply defined, the level of contrast of the letters to the background is reduced, and the presence of glare and reflections on the screen may make viewing difficult.
Viewing distances and angles used for computer work are also often different from those commonly used for other reading or writing tasks. As a result, the eye focusing and eye movement requirements for computer viewing can place additional demands on the visual system. In addition, the presence of even minor vision problems can often significantly affect comfort and performance at a computer. Uncorrected or under corrected vision problems can be major contributing factors to computer-related eyestrain. In most cases, symptoms of CVS occur because the visual demands of the task exceed the visual abilities of the individual to comfortably perform them. At greatest risk for developing CVS are those persons who spend two or more continuous hours at a computer every day.
SYMPTOMS OF COMPUTER VISION SYNDROME
• eye strain
• headaches
• blurred vision
• dry eyes
• neck and shoulder pain
These symptoms may be caused by:
• poor lighting
• glare on the computer screen
• improper viewing distances
• poor seating posture
• uncorrected vision problems
• a combination of these factors
The extent to which individuals experience visual symptoms often depends on the level of their visual abilities and the amount of time spent looking at the computer screen. Uncorrected vision problems like farsightedness and astigmatism, inadequate eye focusing or eye coordination abilities, and aging changes of the eyes, such as presbyopia, can all contribute to the development of visual symptoms when using a computer.
Many of the visual symptoms experienced by computer users are only temporary and will decline after stopping computer work. However, some individuals may experience continued reduced visual abilities, such as blurred distance vision, even after stopping work at a computer. If nothing is done to address the cause of the problem, the symptoms will continue to recur and perhaps worsen with future computer use.
Prevention or reduction of the vision problems associated with Computer Vision Syndrome involves taking steps to control lighting and glare on the computer screen, establishing proper working distances and posture for computer viewing, and assuring that even minor vision problems are properly corrected.
PATHOPHYSIOLOGY OF COMPUTER VISION SYNDROME
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.
DIAGNOSIS OF COMPUTER VISION SYNDROME
Computer Vision Syndrome can be diagnosed through a comprehensive eye examination. Testing, with special emphasis on visual requirements at the computer working distance, may include:
Patient history to determine any symptoms the patient is experiencing and the presence of any general health problems, medications taken, or environmental factors that may be contributing to the symptoms related to computer use. Visual acuity measurements to assess the extent to which vision may be affected. A refraction to determine the appropriate lens power needed to compensate for any refractive errors (nearsightedness, farsightedness or astigmatism).
Testing how the eyes focus, move and work together. In order to obtain a clear, single image of what is being viewed, the eyes must effectively change focus, move and work in unison. This testing will look for problems that keep your eyes from focusing effectively or make in this testing may be done without the use of eye drops to determine how the eyes respond under normal seeing conditions. In some cases, such as when some of the eyes' focusing power may be hidden, eye drops may be used. They temporarily keep the eyes from changing focus while testing is done. Using the information obtained from these tests, along with results of other tests, your optometrist can determine if you have Computer Vision Syndrome and advise you on treatment options.
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 have 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.
TREATMENT OF COMPUTER VISION SYNDROME
Solutions to computer-related vision problems are varied. However, CVS can usually be alleviated by obtaining regular eye care and making changes in how you view the computer screen.
Eye Care
In some cases, individuals who do not require the use of eyeglasses for other daily activities may benefit from glasses prescribed specifically for computer use. In addition, persons already wearing glasses may find their current prescription does not provide optimal vision for viewing a computer. Eyeglasses or contact lenses prescribed for general use may not be adequate for computer work. Lenses prescribed to meet the unique visual demands of computer viewing may be needed. Special lens designs, lens powers or lens tints or coatings may help to maximize visual abilities and comfort.
Some computer users experience problems with eye focusing or eye coordination that can't be adequately corrected with eyeglasses or contact lenses. A program of vision therapy may be needed to treat these specific problems. Vision therapy, also called visual training, is a structured program of visual activities prescribed to improve visual abilities. It trains the eyes and brain to work together more effectively. These eye exercises help remediate deficiencies in eye movement, eye focusing and eye teaming and reinforce the eye-brain connection. Treatment may include office-based as well as home training procedures.
Viewing the Computer
Some important factors in preventing or reducing the symptoms of CVS have to do with the computer and how it is used. This includes lighting conditions, chair comfort, location of reference materials, position of the monitor, and the use of rest breaks.
Location of computer screen - Most people find it more comfortable to view a computer when the eyes are looking downward. Optimally, the computer screen should be 15 to 20 degrees below eye level (about 4 or 5 inches) as measured from the center of the screen and 20 to 28 inches from the eyes.
Reference materials - These materials should be located above the keyboard and below the monitor. If this is not possible, a document holder can be used beside the monitor. The goal is to position the documents so you do not need to move your head to look from the document to the screen.
Lighting - Position the computer screen to avoid glare, particularly from overhead lighting or windows. Use blinds or drapes on windows and replace the light bulbs in desk lamps with bulbs of lower wattage.
Anti-glare screens - If there is no way to minimize glare from light sources, consider using a screen glare filter. These filters decrease the amount of light reflected from the screen.
Seating position - Chairs should be comfortably padded and conform to the body. Chair height should be adjusted so your feet rest flat on the floor. If your chair has arms, they should be adjusted to provide arm support while you are typing. Your wrists shouldn't rest on the keyboard when typing.
Rest breaks - To prevent eyestrain, try to rest your eyes when using the computer for long periods. Rest your eyes for 15 minutes after two hours of continuous computer use. Also, for every 20 minutes of computer viewing, look into the distance for 20 seconds to allow your eyes a chance to refocus.
Blinking - To minimize your chances of developing dry eye when using a computer, make an effort to blink frequently. Blinking keeps the front surface of your eye moist.
Regular eye examinations and proper viewing habits can help to prevent or reduce the development of the symptoms associated with Computer Vision Syndrome.
REFERENCES
1. Thomson WD. Eye problems and visual display terminals--the facts and the fallacies. Ophthalmic Physiol Opt. Mar 1998; 18(2):111-9.
2. Sheedy JE. Vision problems at video display terminals: a survey of optometrists. J Am Optom Assoc. Oct 1992; 63(10):687-92.
3. Hales TR, Sauter SL, Peterson MR, Fine LJ, Putz-Anderson V, Schleifer LR, et al. Musculoskeletal disorders among visual display terminal users in a telecommunications company. Ergonomics. Oct 1994; 37(10):1603-21.
4. Yaginuma Y, Yamada H, Nagai H. Study of the relationship between lacrimation and blink in VDT work. Ergonomics. Jun 1990; 33(6):799-809.
5. Patel S, Henderson R, Bradley L, Galloway B, Hunter L. Effect of visual display unit use on blink rate and tear stability. Optom Vis Sci. Nov 1991; 68(11):888-92.
6. Biswas NR, Nainiwal SK, Das GK, Langan U, Dadeya SC, Mongre PK, et al. Comparative randomised controlled clinical trial of a herbal eye drop with artificial tear and placebo in computer vision syndrome. J Indian Med Assoc. Mar 2003; 101(3):208-9, 212.
7. Chaffin DB. Localized muscle fatigue--definiton and measurement. J Occup Med. Apr 1973; 15(4):346-54.
8. Eng WG. Survey on eye comfort in aircraft: I. Flight attendants. Aviat Space Environ Med. Apr 1979; 50(4):401-4.
9. Grandjean E, Hünting W, Nishiyama K. Preferred VDT workstation settings, body posture and physical impairments. Appl Ergon. Jun 1984; 15(2):99-104.
10. Gunnarsson E, Soderberg I. Eye strain resulting from VDT work at the Swedish telecommunications administration. Appl Ergon. Mar 1983; 14(1):61-9.
11. Izquierdo JC, Garcia M, Buxo C, Izquierdo NJ. Factors leading to the Computer Vision Syndrome: an issue at the contemporary workplace. Bol Asoc Med P R. Mar-Apr 2004; 96(2):103-10.
12. Liao GF, Zhong H, Jiang GH, Mu XF, Wu WC. [Measurement and evaluation of visual index in VDT operators under Multi-user system]. Space Med Med Eng (Beijing). Feb 2000; 13(1):61-4.
13. Schaumberg DA, Sullivan DA, Buring JE, Dana MR. Prevalence of dry eye syndrome among US women. Am J Ophthalmol. Aug 2003; 136(2):318-26.
14. Sheedy JE, Shaw-McMinn PG. Diagnosing and Treating Computer-Related Vision Problems. Boston: Butterworth Book Publishers; 2003.
15. Sotoyama M, Jonai H, Saito S, Villanueva MB. Analysis of ocular surface area for comfortable VDT workstation layout. Ergonomics. Jun 1996; 39(6):877-84.
16. Tsubota K, Nakamori K. Dry eyes and video display terminals. N Engl J Med. Feb 25 1993; 328(8):584.
17. 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 2026-2042.
About the Author
Reader, Bhupal Nobles\' Girls\' College of Pharmacy, Udaipur-Raj.313002 INDIA Email: kamalsrathore@yahoo.com kamalsrathore@gmail.com Mobile: +919828325713
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