Human Technology Interface: Computers & Vision Health

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Astonishingly, adults expose themselves to electronic screens on average of 8.5 hours per day. As technology increases with prolonged near work on computers and hand-held digital devices, more nurses are experiencing eye and vision problems. The Information Age has provided computers not only in the healthcare workplace, but at home and on-person by means of laptops, smart-phones, electronic readers and tablets; smaller in size, but with lower-resolution screens. This human-technology interface can lead to adverse symptoms if >4 hours are spent working on a terminal.

Nearly 20 years ago, the American Optometric Association termed computer vision syndrome (CVS) as the complex of eye and vision problems related to near work experienced while using a computer. CVS symptoms reflect the current broad diagnosis of asthenopia (ICD-9, 368.13) also referred to as eyestrain. Symptoms include: fatigue, blurred distal or proximal vision, headache, dry or irritated eyes, neck and/or backaches, blurred near vision and diplopia (double vision). There are two types of eyestrain grouped into internal or external symptoms.


Eyestrain

                         Internal Symptoms 
(accommodative stress, convergence stress, or uncorrected refractive error)

                        External Symptoms
(dry eye, glare, up gaze, small font, flicker,  
 or environmental factors)

  • Aches or pain felt inside the eye
  • Headache
  • Diplopia (double vision)
  • Blurring
  • Strain
  • Burning
  • Ocular dryness
  • Irritation or tearing

 

Internal symptoms of CVS are the result of inappropriate ocular motor responses caused by either under or over accommodation relative to an object. Adaptation of the eye for near vision work is accomplished by accommodation; the increase curvature of the lens through movement of the ciliary muscles. An accommodative lag occurs when it takes longer for the eye to change fixation from one point to another. Hence, the accommodative system has to work harder with an increased lag, resulting in visual discomfort and eye fatigue. Therefore, with near vision demands or computer work, accommodation lags and fails to fully relax, thereby causing blurred vision and/or eyestrain in the person. Furthermore, myopia or astigmatism needs correction to reduce ocular accommodation and minimize the blur to have clear vision of small targets.

External symptoms occur from environmental factors that produce corneal drying, such as low ambient humidity, high forced-air heating, or air conditioning. There is an association between dry eyes and decreased blink rate when performing computer work, reading low-contrast text or small-sized font, and the presence of glare. A reduced blink rate can lead to an increased evaporation of tears, which then exaggerates dry eye symptoms. Dry eye disease (DED) is a multi-factorial disorder of the tear film and ocular surface resulting in discomfort, visual disturbance and ocular surface damage. Any dysfunction of the lacrimal functional unit (LFU) can lead to DED, which causes alterations in volume, composition, distribution, and/or clearance of the tear film. Low aqueous flow or excessive tear film evaporation can be a result of a dysfunction in any of the LFU components, environmental factors, decreased blink rate, and non-modifiable risk factors such as female gender and older age.


Prevention of Computer Vision Syndrome

 

Routine eye care & exams

  • Corrects vision defects, refractive errors even small astigmatic errors
  • Specific computer glasses may be required to maximize comfort and provide clearer image of the target over time

Dry eye therapy

  • Encourage over-the-counter artificial tear solutions, lubricating drops or ointments

Consciously blink

  • Forcefully blink, now and then to replenish and lubricate the front of the eyes

Rest eyes:
the 20-20-20 Rule

  • Every 20 minutes look away from the computer at a distance of 20 feet for at least 20 seconds

It is important to reduce or eliminate risks for developing CVS, thereby maximizing comfort while using visual digital devices. Asthenopia is seldom serious and usually improves with rest, limiting prolonged reading and near work on computers or digital devices, as well as using computer-specific glasses.


Properly Arrange Your Computer Work Station

 

Set the location of your computer

  • Adjust computer so it is slightly below horizontal eye level
  • Tilt the top of the monitor away from you at a 10° to 20° angle, with the center of the monitor below your eyes creating a downward gaze.
  • It is important that the image on the screen is clear and your head is comfortable

 

Set lighting to avoid glare

  • Overhead lighting or windows; when sitting in front of a computer light sources are not to be directly visible.
  • Turn desk or monitor perpendicularly to minimize glare

 

Use correct seating position

  • Feet flat on the floor with knees bent > 90°
  • Chairs that support the legs without excessive pressure on the back of the thighs
  • Back is snug against the seat, with a thigh-to-trunk angle of  ≥ 90°
  • Wrists and hands are extended nearly straight from the elbow to the home row of the computer
  • Keyboard and monitor are straight ahead and the monitor is placed 20 to 26 inches from your eyes

Individualize the viewing size on the computer

  • Adjust the Zoom; from 75% to 100%, or vice versa. Individualize for comfortable reading

Change the Font

  • Verdana is recommended

Increase screen resolution & font size

  • The better the resolution the clearer the image
  • The larger the font size the easier to see

Adjust contrast and brightness

  • Not too bright and not too dim

Clean your screen

  • Keep free of fingerprints and dust

Place document holders

  • Place at eye level

Figure 1 small.jpg
References

- Computer vision syndrome symptoms: http://www.aoa.org/x5375.xml 

- Collier JD, Rosenfield M. Accommodation and convergence during sustained computer work. Optometry. 2011;82:434-440. 

- Eye Guardian: a framework of eye tracking and blink detection for mobile device users. http://www.hotmobile.org/2012/papers/HotMobile12-final72.pdf

- Gowrisankaran S, Nahar NK, Hayes JR, Sheedy JE. Asthenopia and blink rate under visual and cognitive loads. Optometry and Vision Science. 2012;89(1),97-104.

- Jarvis C. Physical Examination & Health Assessment. 6th ed. St Louis, Missouri: Elsevier Saunders; 2012

- Li H-H, Heus P, Li L, Yang J, Kuang J, Li Y-P, Xiong T. Optical correction of refractive error for preventing and treating eye symptoms in computer users. Cochrane Database of Systematic Reviews 2012, Issue 5.

- Mayo Clinic http://www.mayoclinic.com/health/eyestrain/DS01084/DSECTION=prevention

- Perry HD. Dry eye disease: pathophysiology, classification, and diagnosis. American Journal of Managed Care. 2008:14,S079-S087.

- Rosenfield M. Computer vision syndrome: a review of ocular causes and potential treatments. Ophthalmic & Physiological Optics. 2011;31:502-515.

- Tosha C, Borsting, E, Ridder III WH, Chase C. Accommodation response and visual discomfort. Ophthalmic and Physiological Optics. 2009;29:625-633.

- Toama Z, Ahmed Mohamed A, Abdullah Hussein NK. Impact of a guideline application on the prevention of occupational overuse syndrome for computer users. Journal of American Science. 2012;8:265-282.

Christine.jpgChristine Reese, MSN, MBA, RN, FNP-C
Community Health Alliance-Neil J. Redfield Center

 

 

BernieLongo - little picture.jpgBernadette Longo, PhD, RN, APHN-BC, CNL
Environmental Health Committee - Chair
Orvis School of Nursing – University of Nevada Reno

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