Topic of the Month

Eating to See: Vision, Screen Time and Nutrition

Julia Bird

October 30, 2017

From television to computers to tablets and smart phones—the last decades have seen an unprecedented rise in the use of screens to share information, be entertained and connect. Screens are seemingly ubiquitous with most households having several. The amount of time people spend watching a screen is mind-boggling: an international comparison found that on average, adults spent 5 to 9 hours per day watching their television, computer, smartphone or tablet in the 30 countries surveyed (1). On the one hand, screens have enabled us to learn better, communicate better and increase our productivity. On the other, large amounts of screen time encourage sedentary behavior and can cause eye problems that affect quality of life. Is there a way for us to stop our avid screen use from affecting our vision?

Blue light

The different colors that make up the light we see are beautifully displayed when water droplets refract and disperse light into a rainbow. As the colors of visible light move from red through yellow and green to blue and violet, they increase in energy. Thus, blue-violet light has the greatest amount of energy in the visible spectrum.

Blue light is a normal component of all light, and sunlight is the main source. Indoors, digital devices expose our eyes to blue light. Although the amount of blue light from computer, smartphone and tablet screens is small compared to that from sunlight, the amount of time that we are exposed to blue light and our proximity to the source are a cause for concern. A further issue stems from knowledge that the lens and cornea are capable of blocking damaging UV-light, but not blue light (2).

The high energy content of blue light is likely responsible for its effects on the eye. Blue light increases oxidative stress within the eye when it interacts with vision sensors and pigments (5). Blue light exposure to the visual pigment responsible for vision in low light situations, rhodopsin, caused damage to the retina, whereas green light did not (6). It seems that blue light is more likely to cause discomfort to the eyes that other types of visible light (3), and this may increase eye strain due to squinting (4).

Computer vision syndrome

Overuse of screens has led to a rather common problem, particularly amongst office workers who use a computer for many hours per day: computer vision syndrome (7). Surveys find that between 25 and 40 percent of office workers are affected by a variety of symptoms (8-10). These range from mild to debilitating, and include tired or dry eyes, headache, blurred vision, eye and neck strain, and sensitivity to bright lights. In some cases, sufferers are sent to neurologists and stroke clinics to rule out more serious causes (7), which is concerning for all involved, and places an unnecessary burden on the health care system.

A range of strategies have been identified to help counteract the effects of computer vision syndrome (7):

  • Receive counseling about good practices before prolonged use of screens
  • Keep appropriate distances between the eyes and screens
  • Take regular, short rest breaks for the eyes, such as the 20/20/20 rule: every 20 minutes, a 20 second break, looking 20 feet (7 meters) into the distance
  • Take a longer break for 15 minutes every two hours
  • Use screens in an ergonomic position
  • Use computer glasses or filters on the screen
  • Balance background lighting with screen illumination
  • Treat other eye conditions that may contribute to computer vision syndrome such as dry eyes and astigmatism

Nutritional strategies for computer vision syndrome

Two eye-friendly carotenoids found in many yellow, orange and green leafy vegetables (11) may also help with computer vision syndrome. They are called lutein and zeaxanthin, and they are selectively placed at the back of the eye over the vision sensors responsible for central vision, called the macula (12). Their yellow color acts as a blue-light filter, potentially protecting the delicate photo-sensors from damaging blue light (13). They are also strong antioxidants, and this may be beneficial in highly metabolically active areas of the body such as the eye.

The effect of lutein and zeaxanthin supplementation on computer vision syndrome symptoms was recently tested in a randomized, placebo-controlled clinical trial (4). The study featured 48 college students who normally viewed screens for at least six hours per day at a distance of 3 feet or less, were assigned to a lutein and zeaxanthin supplement (24 mg lutein, zeaxanthin and mesa-zeaxanthin at a ratio of 83:10:7, suspended in oil) or a matching placebo control for six months. At baseline, three months and six months, participants underwent a series of visual tests, and completed questionnaires about their sleep quality and five indicators of excessive screen time. These were headache, blurry vision, neck strain, eye strain and eye fatigue (4).

At baseline, there was already a correlation found between higher levels of lutein and zeaxanthin in the eye (as determined by macular pigment optical density measurements) and less eye strain, eye fatigue and headache. After six months of supplementation, there was an increase in lutein and zeaxanthin in the eye. Headache, eye strain and eye fatigue decreased, and measures of visual performance improved. Interestingly, there was also an improvement in sleep as well (4).

The authors speculate that higher levels of lutein and zeaxanthin in the eye improve the ability of the light-sensitive pigments that are an essential part of vision to regenerate. Thus, the eyes maintain visual performance during long periods of exposure to the blue light from screens with the help of lutein and zeaxanthin. They also suggest that lutein and zeaxanthin screen out some blue light to reduce squinting, a cause of eye strain.

Two other studies that used bilberry extracts, which contain both anthocyanins and a range of carotenoids including lutein and zeaxanthin (14, 15), also showed an improvement in eye complaints due to using screens for an extended period of time (16, 17). The anthocyanins in blueberries could protect the layer of cells that supports the vision cells in the laboratory (18), and other clinical trials have shown that it can improve the ability of the eyes to recover after a flash of bright light (19). 

Improved office ergonomics, appropriate lighting and treating other vision problems is one step to reducing computer vision syndrome. However, making small changes to the diet could also help, like increasing intakes of lutein, zeaxanthin and anthocyanin-rich foods may be a successful strategy to reduce vision complaints related to prolonged screen time. 

 

References

  1. Meeker M. 2014 Internet Trends. 2014. Internet: http://www.kpcb.com/blog/2014-internet-trends.
  2. Mainster MA. Violet and blue light blocking intraocular lenses: photoprotection versus photoreception. Br J Ophthalmol 2006;90(6):784-92. doi: 10.1136/bjo.2005.086553
  3. Stringham JM, Fuld K, Wenzel AJ. Action spectrum for photophobia. J Opt Soc Am A Opt Image Sci Vis 2003;20(10):1852-8.
  4. Stringham JM, Stringham NT, O'Brien KJ. Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure. Foods 2017;6(7). doi: 10.3390/foods6070047
  5. Wu J, Seregard S, Algvere PV. Photochemical damage of the retina. Surv Ophthalmol 2006;51(5):461-81. doi: 10.1016/j.survophthal.2006.06.009
  6. Grimm C, Wenzel A, Williams T, Rol P, Hafezi F, Reme C. Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching. Invest Ophthalmol Vis Sci 2001;42(2):497-505.
  7. Munshi S, Varghese A, Dhar-Munshi S. Computer vision syndrome-A common cause of unexplained visual symptoms in the modern era. Int J Clin Pract 2017;71(7). doi: 10.1111/ijcp.12962
  8. Toomingas A, Hagberg M, Heiden M, Richter H, Westergren KE, Tornqvist EW. Risk factors, incidence and persistence of symptoms from the eyes among professional computer users. Work 2014;47(3):291-301. doi: 10.3233/WOR-131778
  9. Porcar E, Pons AM, Lorente A. Visual and ocular effects from the use of flat-panel displays. Int J Ophthalmol 2016;9(6):881-5. doi: 10.18240/ijo.2016.06.16
  10. Portello JK, Rosenfield M, Bababekova Y, Estrada JM, Leon A. Computer-related visual symptoms in office workers. Ophthalmic Physiol Opt 2012;32(5):375-82. doi: 10.1111/j.1475-1313.2012.00925.x
  11. Humphries JM, Khachik F. Distribution of lutein, zeaxanthin, and related geometrical isomers in fruit, vegetables, wheat, and pasta products. J Agric Food Chem 2003;51(5):1322-7. doi: 10.1021/jf026073e
  12. Bernstein PS, Li B, Vachali PP, Gorusupudi A, Shyam R, Henriksen BS, Nolan JM. Lutein, zeaxanthin, and meso-zeaxanthin: The basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease. Prog Retin Eye Res 2016;50:34-66. doi: 10.1016/j.preteyeres.2015.10.003
  13. Hammond BR, Jr., Fletcher LM. Influence of the dietary carotenoids lutein and zeaxanthin on visual performance: application to baseball. Am J Clin Nutr 2012;96(5):1207S-13S. doi: 10.3945/ajcn.112.034876
  14. Bunea A, Rugină D, Pintea A, Andrei S, Bunea C, Pop R, Bele C. Carotenoid and fatty acid profiles of bilberries and cultivated blueberries from Romania. Chemical Papers 2012;66(10):935-9. doi: 10.2478/s11696-012-0162-2
  15. Karppinen K, Zoratti L, Sarala M, Carvalho E, Hirsimaki J, Mentula H, Martens S, Haggman H, Jaakola L. Carotenoid metabolism during bilberry (Vaccinium myrtillus L.) fruit development under different light conditions is regulated by biosynthesis and degradation. BMC Plant Biol 2016;16:95. doi: 10.1186/s12870-016-0785-5
  16. Kawabata F, Tsuji T. Effects of dietary supplementation with a combination of fish oil, bilberry extract, and lutein on subjective symptoms of asthenopia in humans. Biomed Res 2011;32(6):387-93.
  17. Ozawa Y, Kawashima M, Inoue S, Inagaki E, Suzuki A, Ooe E, Kobayashi S, Tsubota K. Bilberry extract supplementation for preventing eye fatigue in video display terminal workers. J Nutr Health Aging 2015;19(5):548-54. doi: 10.1007/s12603-014-0573-6
  18. Liu Y, Song X, Zhang D, Zhou F, Wang D, Wei Y, Gao F, Xie L, Jia G, Wu W, et al. Blueberry anthocyanins: protection against ageing and light-induced damage in retinal pigment epithelial cells. Br J Nutr 2012;108(1):16-27. doi: 10.1017/S000711451100523X
  19. Kalt W, McDonald JE, Fillmore SA, Tremblay F. Blueberry effects on dark vision and recovery after photobleaching: placebo-controlled crossover studies. J Agric Food Chem 2014;62(46):11180-9. doi: 10.1021/jf503689c