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E-MEDICINE
Year : 2001  |  Volume : 47  |  Issue : 2  |  Page : 119-20

Computers and vision.


Pennsylvania College of Optometry, 8360 Old York Road, Elkins Park, PA 19027, USA. , USA

Correspondence Address:
S B Verma
Pennsylvania College of Optometry, 8360 Old York Road, Elkins Park, PA 19027, USA.
USA
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PMID: 11832604

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Keywords: Computer Terminals, Human, Human Engineering, Vision Disorders, etiology,prevention &control,


How to cite this article:
Verma S B. Computers and vision. J Postgrad Med 2001;47:119

How to cite this URL:
Verma S B. Computers and vision. J Postgrad Med [serial online] 2001 [cited 2014 Oct 21];47:119. Available from: http://www.jpgmonline.com/text.asp?2001/47/2/119/214


Computer technology has revolutionised the work place and the home environment. Who would have thought that in the year 2001 our lives would revolve around computers? According to the 1997 US Census Bureau report, half of all children had a computer at home and approximately 71% of children work with computers in school. Today probably ever child has access to computer either at school, at home or in the library. Similarly, very few working adults may not have access to the computers today. A great majority of retired adults also use computers.


  ::   Computer vision syndrome (cvs) Top


While computers have revolutionized our lives, they have also brought in some job-related complaints and symptoms. Some of the common symptoms associated with excessive use of computers include; frequent headaches, blurry or double vision, burning eyes, focusing difficulties, eye fatigue, eye irritation, excessive tearing, dry eyes, pain in the eyes and frequently blinking and squinting.

Surveys of computer workers reveal that vision related problems are the most frequently reported health- related problems, occurring in over 70 percent of computer workers.[1],[2],[3] The complex of eye and vision problems related to near work experienced during computer use has been called “computer vision syndrome.”[4]

The factors which make it visually demanding while working on a computer include, frequent saccadic eye movements, accommodation and vergence. Problems are noticed when the visual demands of the task exceed the visual abilities of the individual to comfortably perform the task.

Eye movements, focusing and eye alignment processes involve repetitious muscular activity. The movement of each of the eyes is controlled by six extraocular muscles,[5] which are responsible for proper alignment of the eyes when viewing objects such as the computer screen. The ability of the eyes to change focus is controlled by the ciliary muscle, which exerts a force on the internal lens of the eye.[6]

Computer vision syndrome is related to the unique aspects of the task. Working at a computer is more visually demanding than doing other standard office work such as reading printed documents. Aspects of the design of the computer video display such as screen resolution and contrast, image refresh rates and flicker, and screen glare, as well as working distances and angles all may contribute to worker symptoms.[7],[8]

In order to accomplish specific computer related tasks, frequent eye movements from work document to the computer screen, or from the screen to the keyboard and back again, are used. In addition, as the object being viewed changes, so does the need for a change in eye focusing to maintain a clear image. These changes occur repeatedly during computer use. The flexibility of the lens within the eye and weakening of the ciliary muscle gradually decreases with age (onset of presbyopia) ,which affects most people after age 40. This will require a computer use to have proper focusing spectacle correction.

One of the most frequently asked questions is that my vision is 20/20, then I should not have these symptoms. That is not true. Sometimes, low refractive errors including Astigmatism can cause these symptoms. These refractive errors may not affect visual acuity, rather they impact visual comfort and functioning. Some contact lens wearers also experience dry eyes and blurred vision. This is caused by infrequent blinking thereby making the contact lenses dry and dirty.

Presbyopic patients face a different dilemma. A computer worker using a bifocal may often find it heard to focus on the screen. Bifocals are designed to correct the distance vision and normal reading vision which requires holding the reading material from 12 to 16 inches. However, computer screen is viewed from 20 to 24 inches from the eyes. Bifocal wearers have to constantly keep moving back and forth and change their postures to focus the screen. This causes neck stress and eye fatigue. Computer users above 50 years of age must inform their eye doctors that they work on the computer and have these symptoms. Using progressive type of multifocal lenses and frames that can be adjusted to provide a adjustable pantoscopic angle are the most suitable form of visual correction for the computer users. If glare is a problem, using a very light tint or antiglare coating on the spectacle lenses can provide the needed visual comfort.

Many aspects of computer vision syndrome meet the same criteria used to define cumulative trauma disorders or repetitive stress injuries. Because of the impact of computer vision syndrome on worker comfort and productivity, the American Optometry association believes more attention needs to be given to reducing the impact of computer related vision problems in the workplace and to providing appropriate eye and vision care for workers whose computer on a regular basis.

In summary, the computer users should make note of all the symptoms and the adjustments that they have to make to function and discuss these with their eye care providers. Most of the patients using appropriate visual correction and modifications in their work habits can enjoy working on the computers.

 
 :: References Top

1. Collins MS, Brown B, Bowman KJ, Caird D. Task variables and visual discomfort associated with the Use of VDTs. Optom Vis Sci 1991; 68:27-33.  Back to cited text no. 1    
2.Dain SJ, McCarthy AK, Chan-Ling T. Symptoms in VDU operators. Am J Optom Physiol Opt 1988; 65:162-167.  Back to cited text no. 2    
3.Smith MJ, Cohen BGF, Stammerjohn LW. An investigation of health complaints and job stress in Video display operations. Hum Factors 1981; 23:387-400.  Back to cited text no. 3    
4.American Optometry Association. Guide to the clinical aspects of computer vision syndrome. St. Louis; American Optometry Association: 1995. pp1.  Back to cited text no. 4    
5.Davison H. The extraocular muscles and their actions. In: Physiology of the eye (Fifth edition). New York: Pergamon Press, 1990: 647-66.  Back to cited text no. 5    
6.Davison H. Accommodation. In: Physiology of the eye. 5th edn. New York; Pergamon Press: 1990. pp 768-776.  Back to cited text no. 6    
7.Sheedy JE. How do eye problems rank with other VDU disorders? In: Grieco A, Molteni G, Occhipinti B, editors. Work with display units. Fourth International Scientific Conference Book of Short Papers Vol 2. University of Milan, Italy, Oct 2-5, 1994.  Back to cited text no. 7    
8.Campbell FW, Durden K. The visual display terminal use: A consideration of its physiological, psychological and clinical background. Ophthal Physiol Opt 1983; 3: 175-192.   Back to cited text no. 8    



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