Posted by: Carolinas Center for Sight in Eye Health

Mobile devices have become ubiquitous. It has been estimated that 90% of Americans have cell phones; smartphones account for 70%. Overall, 4 billion cell phones were used worldwide in 2013, with up to 5.0 billion expected by 2019. Social media sites are often checked first thing upon awakening. In 2015, as many as 75% of us use at least one social media site and the average smartphone user has 7 social media apps. Up to 80% of Americans keep their smartphones with them almost throughout the day and night. In short, smartphones are our mini-mobile computers upon which we depend all of the time. However, our eyes will be more comfortable, our sleep more regular and refreshing, and our bodies overall more healthy if we limit our mobile device use, video-gaming, and desktop computer use to daylight and early evening hours, taking care to avoid any unnecessary viewing after going to sleep. 

There are several negative effects of frequent or prolonged use of mobile devices such as cell phones, electronic tablets, and laptops. These go beyond the socially disruptive and addictive behavior of playing video games and incessant social-networking, the dangers of texting while driving or while a pedestrian crossing the street, and the colonization of screens and keyboards with multiple bacteria due to poor hand hygiene, including E.Coli (16%) and MRSA. In addition, these devices require use of the eyes and it is not surprising that ocular and visual dangers exist. Negative effects on the eyes include asthenopia, dry eyes, interruption of day/night cycle, and blue-light damage to the eyes. One cause of blurred vision is called asthenopia, the fatigue we experience with prolonged viewing especially at near or when reading. With prolonged use, the lens muscle becomes tired and may produce blurred images as well as an ache felt in the eye or eyebrow. It can sometimes be relieved by wearing the correct spectacles or contact lenses to correct vision, and may also improve with periodic breaks from staring activity. The eyelids and tear system are important to our eyes and vision. A dry cornea (in front of the iris) is naturally bumpy on a microscopic scale and presents blurred images. The eyelids work like reverse-windshield-wipers to spread the tears over the cornea. The tears provide a smooth layer of water that keeps the cornea comfortable as well as making it a superior quality lens to give you the clearest vision possible. Thus, dry eyes are another cause of blurred vision. Any reading or viewing activity may involve staring in order to enhance reading or to follow video-gaming. 

Prolonged gazing is common when using mobile devices as well as desk-stop computers and flat screen TVs. This is necessary in order to take in the images presented at a fast refresh rate. (In contrast, print material induces less riveted viewing due to the pigment in ink which doesn’t go on-and-off like lights.) In turn, this intent gaze decreases our blink rate resulting in corneal drying. In turn, we experience burning, tearing, and blurred vision which can be temporarily relieved by blinking or the instillation of artificial tears. Staring activities are even more problematic for those already diagnosed with ‘dry eyes’, rheumatoid arthritis, or Sjogren’s syndrome. When light reaches the retina, the signal travels along the optic nerve to the pineal gland inhibiting the production of melatonin. At night, these impulses normally would stop because when no light stimulates the hypothalamus, melatonin is released from the pineal gland to the body. Those who work night shift or are exposed to light at night will continue to inhibit the production of melatonin. This throws off the sleep/wake cycle and interestingly also places one at greater risk of heart disease, diabetes, gastrointestinal illnesses and reproductive problems. 

For those whose diurnal clocks are miscued for years, there may be higher risks for cancers. This inhibition of melatonin secretion occurs in modern society due to artificial lighting in our homes, but is more accentuated when viewing the blue-based light of TV, computer monitors, and mobile devices. This makes it more difficult to fall asleep as well as to get back to sleep after awakening and checking our phones for social messages. It also may produce temporary night-blindness in one’s eyes, requiring time to recover normal night vision.

The light we receive from the sun contains visible and invisible wavelengths, including “short” blue light, about 450 nanometers. Mobile devices and light from LEDs is primarily blue light as well. When the wavelength of light is shorter, the frequency of light increases and the energy of the light increases as well. There are investigations which suggest that this high energy light may result in higher risk of macular degeneration, injuring the cells which support the cone photoreceptors in the central “20/20” part of the retina, decreasing the sharpness of our vision and threatening our vision for driving, reading, and seeing detail. It is becoming clear that our eyes will be more comfortable, our sleep more regular and refreshing, and our bodies overall healthier if we limit our cell phone and tablet use, as well as our video-gaming, to daylight and early evening hours, taking special care to avoid any unnecessary viewing within a couple of hours of going to bed or after going to sleep.