REVIEW Therapeutic Topics How to Fight Computer Vision Syndrome Advice on treating one of the possible epidemics of the 21st century. SINCE THE ADVENT OF VIDEO DISPLAY terminals and personal computers, a condition known as Computer Vision Syndrome, or CVS, has been on the rise. Millions of computer users commonly complain of eyestrain, headaches, blurred and double vision, dry and irritated eyes, photophobia, and neck and/or back pain. According to some reports, the diagnosis and treatment of these symptoms costs almost $2 billion each year. As computer users become more concerned with CVS, it is important that ophthalmologists be made aware of this rapidly evolving disorder and determine whether or not it should be termed a ‘syndrome.’ This installment of Therapeutic Topics will investigate the methods of evaluating CVS, examine its suspected causes and review the current treatments. Diagnosis We have all encountered patients complaining of problems associated with computer use (Figure 1). However, these symptoms can be By Mark B. Abelson, MD and George W. Ousler III, BS vague, and may be related to problems like chronic fatigue or stress-related disorders. To diagnose a patient with CVS properly, we must first eliminate other possible causes of discomfort. For example, blurred vision can result from uncorrected refractive error (e.g., hyperopia, myopia, astigmatism), improper prescription lenses or presbyopia. Known muscle disorders such as phoria or tropia may induce eyestrain and headaches. Cataracts or corneal scarring can result in glare symptoms. Ask patients about their computer usage, habits and workstation ergonomics. These questions can often provide insight for diagnosis and potential treatment. If the patient’s complaints continue to include the described symptoms, all other possible causes have been ruled out, and computer usage exceeds more than two consecutive hours per day, then more often than not the patient is suffering from CVS. Symptoms of the syndrome in question are often both ocular and musculoskeletal. Any combination of these symptoms may be present and should not be taken lightly. Causes CVS symptoms can arise from a combination of visual problems, poor computer workstation conditions, and improper computer user habits. One of the most significant problems is the reduction in a patient’s blink rate. Studies show that individuals blink approximately 66 percent less when using a computer. Possible explanations for the decreased blink 114 RPg9.indd 114 J ULY 1999 • R E V I E W O F O P H T H A L M O L O G Y 4/12/11 2:04 PM Figure 1. Common Symptoms of Computer Vision Syndrome Eyestrain Headaches Blurred and Double Vision Dry and Irritated Eyes Photophobia Neck and Back Pain rate include concentration on the task or a relatively limited range of eye movement. Consequently, the tear film gets replenished less frequently and evaporates more quickly, causing ocular discomfort. Improper ergonomics may also influence symptoms of CVS. The placement of a video display terminal often requires individuals to gaze upward, widening their interpalpebral fissure. This increases the exposure of the ocular surface to the environment, contributing to the accelerated loss of the tear film. This viewing angle may also result in incomplete interpalpebral closure, further enhancing a deficiency in lubrication by the blink reflex. The process by which an image is displayed on video display terminals can also induce ocular discomfort. The images consist of thousands of tiny, bright spots, better known as pixels, which collectively form an unresolved image that lacks sharp edges. This requires the user’s accommodative mechanism to refocus continuously, inducing ciliary muscle fatigue. The result can include blurred or double vision, headaches, eyestrain and irritated eyes. The lighting conditions of a workstation can also adversely affect a computer user’s ocular comfort. The constant, bright illumination of overhead fluorescent lighting, large windows and/or desk lamps often washes out the images of video display terminals. Improper screen settings or reflections of objects located near the computer can also interfere with viewing. This causes the user to focus intensely in order to properly process the images. In addition to ocular symptoms, many individuals develop bodily symptoms as well. If the patient’s focal length is inappropriate for viewing the screen (the ideal viewing distance is 20 to 24 inches), or if glare is present, many individuals will position their head, neck, or back awkwardly to achieve adequate viewing of the screen. After extended periods, this adapted posture is the perfect recipe for musculoskeletal pain of the neck and shoulder. Brow and facial muscle fatigue or spasms may also develop. Treatment When treating a patient, we should consider both ocular therapy and the adjustment of the computer user’s workstation and/or habits. Lubricating drops. These are a simple and effective therapy for the inevitable reduction of an individual’s blink Figure 2. Etiology and Suggested Therapies of Computer Vision Syndrome ETIOLOGY SUGGESTED THERAPIES Refractive Problem Viewing Distance (ideally, 20 - 24 inches from VDT) Scheduled Breaks from VDT/Prism Lower VDT/Modify Posture/ Patient Awareness Brow and Facial Muscle Massage/ Patient Awareness Frequent Use of Lubricant Eye Drops/ Lower VDT/Increase Blink Rate Correct Adverse Environment Factors (e.g., Humidifier) Equalize Lighting/Anti-reflective Screen Filter Phoria / Tropia Musculoskeletal Pain (e.g., Neck and Shoulders) Brow and Facial Muscle Fatigue or Spasm Ocular Surface Irritation/ Reduced Blink Rate Adverse Environmental Factors (e.g., Air Conditioning) Screen Glare R RPg9.indd 115 rate and tear film. An over-the-counter tear substitute can periodically rewet the ocular surface, contribute to tear volume, and maintain the proper balance of salts and acidity while viewing a terminal. Prescribe them PRN. Adjust the monitor. To further minimize the drying, recommend that the patient position his video display terminal 10 to 20 degrees below eye level. This minor alteration allows patients to gaze downward, narrowing the interpalpebral fissure, improving the fullness of the blinks, and reducing tear film loss. This more natural posture also can help alleviate musculoskeletal pain. Relax accommodation. To minimize accommodative spasms caused by video displayed images, recommend that the patient vary his focal point, or look away from the computer screen, at least one to two times every hour of computer usage. This provides the patient with temporary relief from the continual visual accommodation and glare of the monitor. Available on the market today are Windows-based interactive software programs (e.g., Vision Guard, www.visionguard.com), E V IE W O F O P H T H A L M O L O G Y • JU L Y 1999 115 4/12/11 2:04 PM REVIEW Therapeutic Topics The Effects of Computer Use on the Ocular Surface designed to remind individuals when to perform these exercises and relax their eyes. Get the light right. In the ideal environment, all objects in the patient’s visual field should be equal in brightness. The light should never be behind the video display terminal. By the same token, computer users should not work in the dark. The contrast between computer-generated light and lack of background light can lead to symptoms. It should go without saying that a light should not be aimed directly at the computer monitor. This will result in glare. If direct light is present that can’t be altered, an anti-reflective screen filter may help reduce the glare. Using a computer for as little as 45 minutes results in a drop in blink rates of 57 percent, leading to significant keratoconjunctivitis and discomfort. Those were among the results of a study we completed here in our center. To measure the effects of computer use on the ocular surface, we performed baseline exams on healthy computer users. We then placed them in a room we call the Controlled Adverse Environment Model, or CAE. The room, which contains a computer, has regulated humidity, temperature and airflow. We assigned all the subjects tasks to perform on the computer. Half of all the subjects administered lubricant eye drops 15 minutes after exposure. The rest received no treatment at all. The users were asked to evaluate their ocular comfort at 15 (pre-instillation), 20, 25, 30 and 45 minutes. After exposure, subjects underwent exit examinations, including slit-lamp, fluorescein staining, tear break-up time, blink rate and visual acuity. All the subjects demonstrated a mean increase in keratitis by 1.3 units (on a 4-unit scale), a mean increase in conjunctival fluorescein staining of 2.9 units (on a 4 unit scale), an 18 percent decrease in mean tear break-up time, and a 57 percent decrease in blink rate. The drops resulted in a mean improvement of 1.1 units on a 4-unit subjective comfort scale. The relief lasted 15 to 30 minutes after drop instillation. Untreated subjects’ ocular discomfort scores remained the same or worsened during the same time period. The Future It’s reasonable to believe that as our society’s dependence on computers, on-line services and the Internet increases, so too will the frequency Figure 3. The ideal position for using a VDT. The screen should be 20 degrees below the line of primary gaze. and severity of CVS. What we need is prevention, not a short-term remedy. We need a global treatment plan encompassing not only ocular agents but also patient education and ‘user friendly’ workstations. Then, perhaps what some are calling the “ocular epidemic of the 21st century,”will soon be ancient history. RO Reprinted with permission of the American Optometric Association Dr. Abelson, an Associate Clinical Professor of Ophthalmology at the Harvard Medical School, consults in ophthalmic pharmaceuticals. Collins MJ, Brown B, Bowman KJ, Caird D. Task variables and visual discomfort associated with the use of VDT’s. Optom Vis Sci. January 1991; 68 (1):27-33. Melino C, Melino G, Azzaro GP. Work at video display terminals. Clin Ter. November 1991 15-30; 139(3-4): 121-35. Grant AH. The computer user syndrome. J Am Optom Assoc. November 1987; 58 (11): 892-901. Von Stroh R. Computer vision syndrome. Occup Health Saf. October 1993; 62 (10): 62-6. Ford W. VDT users should get regular eye exams. Occup Health Saf. February 1987; 56 (2): 70. Ousler GW, PJ Gomes, HJ Crampton, MB Abelson. ‘The Effects of a Lubricant Eye Drop on the Signs and Symptoms of Computer Vision Syndrome (CVS) Exacerbated in a Controlled Adverse Environment.’ Abstract. ARVO 1999. Volume 40; No. 4: S540. 116 RPg9.indd 116 J ULY 1999 • R E V I E W O F O P H T H A L M O L O G Y 4/12/11 2:04 PM