Computer Vision Syndrome 

Computers are one of the most fascinating inventions of the 20th century. However, computer users confront new challenges both at their workplace and school systems. By working long hours using a computer monitor, a compilation of systemic and ocular symptoms may develop.

According to the United States Bureau of Labor Statistics, computers are used in the United States, by 100 million people at their jobs daily. Further, according to the National Center for Education Statistics, 95% of schools and 62% of all classrooms in the United States have had computers since 1999.

Definition

Both visual and ophthalmic symptoms occur among computer users. These have collectively been called the computer vision syndrome (CVS). Ocular symptoms associated with the syndrome include decreased vision, burning, stinging, and photophobia.^{[1, 2, 3]}

Frequency

A large percentage of computer users have eye symptoms and, thus, seek eye examinations. According to Thompson, the prevalence of ocular symptoms in computer users, as part of the computer vision syndrome, ranges from 25-93%.^[4]

Studies by Sheedy and coworkers suggest that 1 out of 6 patients requiring eye examinations have a computer-related eye problem.^[5] The cost of eye care examinations and glasses made for computer users is a nearly $2 billion industry, although these costs are certainly not all directly a result of the computer vision syndrome.

Comorbidities

Hales and coworkers reported that approximately 22% of computer workers have musculoskeletal problems, such as neck problems, back problems, shoulder problems, and/or carpal tunnel syndrome.^[6]

The etiology of computer vision syndrome (CVS) is multifactorial. Several issues may lead computer users to this syndrome. These factors may be environmental, personal, or a combination of both.^[7]

Environmental factors

Computer users gaze at the computer monitor at a particular angle of gaze. A wide variety of angles exist in workstation and desk settings. Further, a large variety of light fixtures and illumination sources exist at the workplace. Rarely, illumination is evaluated at the workplace.

Personal factors

Uncorrected refractive errors may contribute to CVS due to fatigue with visual tasks. Computer users who are middle aged and older may have presbyopia. Presbyopia decreases near and intermediate visual acuities, which are needed for the various working distances of computer users.

Working for prolonged periods of time looking at the computer monitor is a risk factor that may also lead computer users to have eye symptoms. Further, patients with preexisting dry eyes may have exacerbated symptoms when using a computer.^{[8, 9]}

Combined factors

Computer users who have presbyopia and dry eye (personal factors), who gaze at the monitor with an extended neck (environmental factor) may have symptoms associated with this syndrome.

History

The patient's history should be obtained, including age, chief complaint, and onset of symptoms.

• In obtaining a history of present illness, the ocular symptoms should be evaluated. Patients with computer vision syndrome (CVS) complain of several symptoms, such as blurred vision, dryness, burning sensation, stinging, red eyes, tearing, and photophobia.
• Previous eyeglasses prescriptions and eye medications, including lubricants, should be evaluated.
• The review of systems may include such issues as xerostomia, thyroid disease, menopause, arthritis, carpal tunnel syndrome, Parkinson disease, and systemic medication use that may exacerbate dry eye symptoms (eg, anticholinergics, antihistamines, antidepressants, diuretics).^[10]
• Environmental factors, such as computer setup, seating, wrist position, monitor type (cathode ray tube vs plasma), desktop color, window proximity, and ceiling and desk illumination sources, should be evaluated.^[11]

Physical

Patients with CVS should undergo a comprehensive ophthalmic evaluation that includes the following:

• Best-corrected visual acuity for near, intermediate, and distance vision
• Manifest refraction at near, intermediate, and distance for refractive errors - Computer users may have refractive errors, including presbyopia.
• A slit lamp examination to evaluate tear meniscus and corneal staining

  • Patients with this syndrome may have superficial punctate keratitis.
  • The lens should be evaluated for cataract formation.
• Intraocular pressure should be evaluated.
• A fundus examination to evaluate the optic nerve, vessels, macula, and peripheral retina
• A cycloplegic refraction is of utmost importance because young computer users with this syndrome may have refractive errors, particularly latent hyperopia, that may lead to visual symptoms.
• A Schirmer test to evaluate for dry eye

The general physical features in patients with CVS include neck muscle spasms.

The general environmental evaluation in patients with CVS includes the following:

• Angle of gaze

  • Previous studies suggest that the angle of gaze is the most important risk factor that leads computer users to develop CVS. For this reason, it is of utmost importance to estimate the angle of gaze needed to look at the computer's monitor. For the purpose of this discussion, the center of the monitor will be used as a reference point to measure distances both from the floor and from the lateral canthal area, as shown in the image below. Angle of gaze.
  • To calculate the angle of gaze that a patient uses at the workstation, the ophthalmologist may measure or ask the patient to measure the following:
    • The distance from the computer user's body to the center of the monitor (labeled as A)
    • The distance from the floor to the center of the computer monitor (labeled as B)
    • The distance from the floor to the lateral canthal area of the patient's eye (labeled as C)
  • The absolute value of the difference between the distance from the floor to the center of the computer's monitor (labeled as B) and the distance from the floor to the lateral canthal region of the computer user's eye (labeled as C) is calculated and labeled as D. In other words, ([B - C]) equals (D).
  • Using this information, the angle of gaze that a patient uses to look at the center of the monitor is calculated using the following formula:

Angle of gaze = tan-1 (D/A)

• Estimate room humidity.
• Evaluate room luminance.

Causes

Environmental factors, such as a large angle of gaze, low humidity, and excess room illumination, may exacerbate the symptoms associated with this syndrome in computer users.

Computer users open their interpalpebral fissures to look at their monitors, as opposed to office clerks who look downward at their desktops. Therefore, computer users have more eye surface exposure to environmental factors, which may lead to increased tear evaporation.

• Previous studies show that the angle of gaze is the most important risk factor that leads computer users to develop CVS. When the monitor's center is positioned higher than the intercanthal region, both the angle of gaze needed to look at the monitor and the interpalpebral aperture are wider. On the other hand, when the monitor's center is lower than the intercanthal region, both the angle of gaze needed to look at the monitor and the interpalpebral aperture are smaller. Symptoms associated with this syndrome are diminished when computer users gaze downward at angles of 14 degrees or more.
• Sheedy and coworkers believe that light sensitivity is worst in computer users, as compared to other office clerks, since computer users keep their eyes wide open to look at the monitor.^[12] Many patients with CVS complain of light sensitivity, which is worsened by high wattage fluorescent or flickering lights at the workplace. Computer users may have discomfort and glare from overhead fluorescent lights and large glass windows that are close to their workstations. Personal factors may also exacerbate the symptoms associated with CVS.
• Age and sex: Previous studies have shown that female patients, as compared to male patients, tend to have a reduction in the tear film's aqueous layer with increasing age.
• Uncorrected refractive errors may lead to blurred vision, asthenopia, eye fatigue, and headaches. Even though presbyopes may wear bifocals, computer users who wear bifocals may have to extend their neck to focus on the monitor, reading material, and/or the keyboard, which are usually located at intermediate distances. Neck extension for prolonged periods of time may also lead to neck pain and headaches as part of the syndrome.
• Symptoms associated with this syndrome, such as burning sensation of the eyes, may be exacerbated in computer users with preexisting dry eyes.
• Diseases that widen the interpalpebral fissures or lead to lid retraction, such as thyroid disease, may lead to increased tear evaporation.
• Diminished blinking: Studies by Yaginuma et al and Patel et al showed that computer users have a diminished blinking frequency.^{[13, 14]} Normally, patients tend to blink approximately 18 times per minute. Patel and coworkers showed that computer users blinked only 4 times per minute.^[14] A reduced blinking rate in computer users may be part of an effort to gaze attentively at the computer monitor.
• Combined factors: Computer users who are presbyopic may need to extend their neck to look at the monitor through the bifocals. Symptoms may be exacerbated further by having an upward gaze to look at the computer's monitor.

Blepharitis, Adult

Conjunctivitis, Allergic

Dry Eye Syndrome

Lagophthalmos

Presbyopia

Refractive errors

Lab studies

A hormonal evaluation, such as a thyroid profile and sex hormones, may be needed.

Imaging studies

X-ray films of the neck may be needed to evaluate cervical vertebral curvature straightening in patients with neck pain. Orthopedic consultation or wrist MRI scans to evaluate the possibility of carpal tunnel syndrome may contribute to a complete diagnostic evaluation.

Other tests

Luminance evaluation by electrical engineers (when feasible) conducted at the workplace is advisable.

A primary care provider should lead and coordinate the multisystemic evaluation of patients with computer vision syndrome (CVS). Awareness of both the ocular findings and the systemic findings is essential in the management of patients with the syndrome.

Indications used for eyeglass prescriptions in the general population are also used for patients with this syndrome. Glasses should be prescribed for patients with refractive errors, including presbyopia. Occupational glasses may be needed by some patients with this syndrome. Single vision lenses versus bifocals should be chosen according to the patient's needs and working distances.

Medical therapy for dry eye symptoms as part of this syndrome includes the following:

• Topical lubricants
• Cyclosporine A ophthalmic emulsion
• Punctal occlusion

Surgical care

Surgical indications used for patients with dry eye syndrome are also used for patients with CVS. Some patients may benefit from punctal plug insertion.

Consultations

Since several ergonomic factors may contribute to CVS, engineer consultation is desirable at the workplace, including luminance evaluation of the working area.

Orthopedic and/or physical therapy evaluation is crucial in the diagnosis and treatment of cervical myositis and carpal tunnel syndrome in patients with this syndrome.

Topical ocular tear replacement therapies are available with either vanishing preservatives or as preservative-free ophthalmic drops.

Refresh Tears (Allergan), a lubricant eye drop, is available with varying characteristics and viscosities. Refresh Tears is supplied in 15 cc and 30 cc bottles, for repeated use, using the sodium chlorite Purite, a vanishing preservative system. A more viscous preparation, Refresh Liquigel is also available.

Systane (Alcon) and Systane Preservative free (Alcon) are lubricant eye drops that contain active demulcents such as polyethylene glycol 400 and propylene glycol buffering preservation system. Original Systane is preserved with Polyquad and formulated at a pH of 7.0.

GenTeal (Novartis) is the original vanishing preservative tear replacement therapy. GenTeal is also available in a user-friendly nighttime gel.

Restasis (cyclosporine A ophthalmic emulsion) 0.05% (Allergan) is indicated to increase tear production in patients whose tear production is presumed to be suppressed due to ocular inflammation associated with chronic dry eye. Restasis has revolutionized the treatment of chronic dry eye disease, and it provides a preservative-free emulsion that also replaces both the aqueous and the lipid component of the tear film. Restasis should not be used by patients with active infections of the eye or by patients with known or suspected allergies to any of the ingredients in the formulation. Restasis has not been studied in patients with a history of herpes viral infections of the eye. The most common adverse effect (experienced by approximately 1 in 5 patients) following the use of Restasis is ocular burning sensation.

Further outpatient care

Evaluation and treatment of myositis and carpal tunnel syndrome are recommended.

In/out patient medications

Indications for prescribing ophthalmic medications for patients with CVS are the same as those for patients with dry eye syndrome.

Deterrence/prevention

Patients should avoid medications (eg, antihistamines, anticholinergics) that may worsen dry eye.

Computer users who have dry eye should avoid wearing contact lenses, especially in the late evening and at night when tear production is at its lowest.

Complications

Complications in patients with CVS are similar to those in patients with dry eye, including superficial punctate keratitis and keratitis.

Watch for optical decentration in eyeglasses by examining the patient's pupillary distance (PD). Consider using monocular PD measurements as needed. The patient's PD should be compared to the PD found in prescribed eyeglasses. Consider advising the optician on the patient's dominant eye.

Watch for bifocal height malpositioning in eyeglasses. Consider advising the optician on the patient's dominant eye.

Prognosis

Early evaluation, diagnosis, and intervention may prevent the symptoms associated with CVS. Symptoms associated with this syndrome may be improved with lubricants.

Patient education

Educate employers and school administrators to conduct luminance and humidity evaluations at the workplace.

Proper monitor positioning to decrease the angle of gaze at the monitor will also help in preventing the symptoms associated with the syndrome.

Employees and students may benefit from educational programs about risk factors and symptoms associated with CVS.

For excellent patient education resources, visit eMedicine's Eye and Vision Center. Also, see eMedicine's patient education article Dry Eye Syndrome.