You are not the only one if you find your vision becomes blurry or your eyes get irritated after hours staring at a computer screen. These symptoms may be a sign of computer vision syndrome (CVS), also known as digital eye strain. CVS describes visual symptoms that result from prolonged use of a digital device such as a computer, smartphone, or tablet. With CVS, people often experience dry eye, eye strain, eye irritation, headaches, or even neck and shoulder pain. As our use of digital devices continues to increase, CVS is likely to become more prevalent. The 2014 Vision Council survey found that over 60% of adults between ages 20 and 50 have experienced symptoms of CVS . Although people with CVS often only have transient vision problems associated with significant electronic use, there are those who may experience progressively worsening visual symptoms with each recurrence . Visual discomfort can also impact our ability to work.
CVS, a repetitive eye strain disorder, occurs when the “visual demands of the task exceed the visual abilities of the individual to comfortably perform them” [2,3]. Those who spend four or more continuous hours using a digital device are at higher risk for developing this syndrome . Based on results from the Vision Council’s most recent report, a great portion of the adult population is at risk for CVS. The organization’s survey of 9,749 adults found that 60.8% of adults spend 5 or more hours on a digital device every day . People with uncorrected vision problems such as presbyopia are also more likely to experience visual fatigue, as their eyes are not able to properly focus light on the retina. Poor lighting is another contributor to CVS, particularly when bright surrounding illumination reduces screen contrast and increases screen glare.
Dry eye is a major risk factor for visual fatigue and other symptoms of CVS. People typically blink around 18 times per minute [3,5]. However, the blink rate for people using a computer is significantly less at an average of 3.6 blinks per minute . This decreased blink rate leads to an increase in exposed ocular surface area and a reduction in tear fluid integrity, thereby accelerating eye desiccation . Increased corneal exposure can also occur when an electronic screen is viewed in primary gaze with eyes looking straight ahead, as opposed to viewing at a downward angle. A cross-sectional study published in JAMA Ophthalmology found that prolonged use of digital devices is associated with decreased concentrations of MUC5AC, a mucin secreted by goblet cells in the conjunctiva that acts as a lubricant in human tears . These results illustrate the close physiologic relationship between CVS and dry eye disease.
Extended use of digital devices at closer viewing distances and more upward gaze angles can increase visual demands on appropriate vergence responses. Blurred vision may be a result from “an inaccurate accommodative response or the failure to fully relax the accommodative reflex” following a sustained near-vision task . As opposed to reading printed materials, reading from a digital screen can be more demanding on our visual systems when there is glare on the screen and a reduced contrast ratio between letters and the background. A 2011 study found that under similar viewing conditions, visual symptoms were significantly worse after prolonged computer use when compared to reading from hardcopy text (p = 0.04) . Results from this study imply that symptoms associated with CVS are not simply a result from performing sustained near-vision tasks, but are specifically tied to use of an electronic device.
Although it is still uncertain if CVS is a significant risk factor for myopia onset or progression, studies have shown that prolonged use of a digital device and higher periods of reading print can lead to a small, transient myopic shift . Moreover, increased near-range visual tasks and decreased exposure to natural light through outdoor activities have both been associated with higher rates of early myopia . A prospective 2013 study found that outdoor activity during class recess was associated with a significantly lower onset of myopia (8.41% versus 17.65% in the control group, p < 0.001) and a lower myopic shift . These findings suggest that as children spend more time using electronic devices and reading print instead of engaging in outdoor activities, they may be at higher risk for myopia. The mechanism of the protective effect of outdoor activities on preventing development of myopia is unclear. It has been suggested that because “light intensities are typically higher outdoors than indoors,” pupils tend to be constricted with outdoors activities and as a result, images are not as blurred . Another hypothesis is that dopamine released from the retina after light stimulation can inhibit eye growth and therefore decrease myopic progression.
Exposure to blue light from electronic screens can affect sleep cycles, as blue light suppresses the release of melatonin . There are also possible links between exposure to blue light and age-related macular degeneration (AMD), although this association is still under much debate. Blue light exposure can lead to photochemical reactions that produce cytotoxic reactive oxygen species (ROS) . The release of ROS can cause oxidative stress that contributes to the development of AMD . It has therefore been postulated that cumulative exposure to blue light from digital devices may damage retinal cells and put people with CVS at higher-risk for AMD. However, there have not been rigorous studies assessing the relationship between CVS and AMD. Some organizations have supported the use of blue light-blocking lens that reduce the penetration of blue light into the retina, although there currently is little evidence that these specialty lens help manage CVS symptoms.
As we continue to use electronic devices on a frequent basis, it can be valuable to know preventive measures and treatments for CVS. Correcting refractive errors from myopia and presbyopia will increase visual acuity and ensure that retinal images are focused appropriately . In order to minimize awkward head positioning and neck pain, ophthalmologists can determine an individuals’ optimal computer working distance and prescribe occupational bifocals specifically for computer use and reading. Dry eye and eye strain can be relieved by lowering the monitor so that the middle of the screen is approximately 5 to 6 inches below eye level, blinking more often during digital device use, and taking more frequent breaks during long work periods . These regular breaks during electronic device use will relax the ocular accommodative system and minimize visual fatigue. The American Optometric Association recommends resting your eyes for 15 minutes after 2 hours of continuous computer use . Moreover, the “20-20-20 break” may be helpful for those who frequently have dry eyes. With this break, one looks at an object 20 feet away for 20 seconds after every 20 minutes of digital device use [1,2]. Other simple steps to manage CVS-related symptoms include increasing text size and adjusting the contrast ratio to make text easier to read, positioning the electronic screen to minimize glare, and avoiding excessive brightness around the screen and aiming instead for “equalized brightness throughout the visual field” .
Dr. Stephanie E Wu is a physician resident, internal medicine, NYU Langone Health
Peer reviewed by Joel Solomon, MD, Opthalmologist, NYU Langone Health
Image courtesy of Wikimedia Commons
- Council V. 2015 Digital Eye Strain Report 2015; https://www.thevisioncouncil.org/sites/default/files/VC_DigitalEyeStrain_Report2015.pdf
- Association AO. Computer Vision Syndrome. http://www.aoa.org/patients-and-public/caring-for-your-vision/protecting-your-vision/computer-vision-syndrome?sso=y.
- Blehm C, Vishnu S, Khattak A, Mitra S, Yee RW. Computer vision syndrome: a review. Surv Ophthalmol. 2005;50(3):253-262.
- Rosenfield M. Computer vision syndrome: a review of ocular causes and potential treatments. Ophthalmic Physiol Opt. 2011;31(5):502-515. https://www.ncbi.nlm.nih.gov/pubmed/21480937
- 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. 1991;68(11):888-892. https://www.ncbi.nlm.nih.gov/pubmed/1766652
- Cardona G, Garcia C, Seres C, Vilaseca M, Gispets J. Blink rate, blink amplitude, and tear film integrity during dynamic visual display terminal tasks. Curr Eye Res. 2011;36(3):190-197.
- Uchino Y, Uchino M, Yokoi N, et al. Alteration of tear mucin 5AC in office workers using visual display terminals: The Osaka Study. JAMA Ophthalmol. 2014;132(8):985-992. https://www.ncbi.nlm.nih.gov/pubmed/24903353
- Chu C, Rosenfield M, Portello JK, Benzoni JA, Collier JD. A comparison of symptoms after viewing text on a computer screen and hardcopy. Ophthalmic Physiol Opt. 2011;31(1):29-32.
- Ramamurthy D, Lin Chua SY, Saw SM. A review of environmental risk factors for myopia during early life, childhood and adolescence. Clin Exp Optom. 2015. https://www.ncbi.nlm.nih.gov/pubmed/26497977
- Wu PC, Tsai CL, Wu HL, Yang YH, Kuo HK. Outdoor activity during class recess reduces myopia onset and progression in school children. Ophthalmology. 2013;120(5):1080-1085.
- Rose KA, Morgan IG, Ip J, et al. Outdoor activity reduces the prevalence of myopia in children. Ophthalmology. 2008;115(8):1279-1285.
- Margrain TH, Boulton M, Marshall J, Sliney DH. Do blue light filters confer protection against age-related macular degeneration? Prog Retin Eye Res. 2004;23(5):523-531. https://www.ncbi.nlm.nih.gov/pubmed/15302349
- Chamorro E, Bonnin-Arias C, Perez-Carrasco MJ, Munoz de Luna J, Vazquez D, Sanchez-Ramos C. Effects of light-emitting diode radiations on human retinal pigment epithelial cells in vitro. Photochem Photobiol. 2013;89(2):468-473.