written by Michael Cole, OD, Child and Family Eye Care Center
Screen time is a topic frequently brought up by parents in our office. Many children are spending increasing amounts of time with digital devices, playing video games and apps, and spending less time in physical and outdoor play. This trend is not without consequence in regard to the visual system, especially in young, developing minds.
Near visual tasks are particularly hard on the eyes for a few reasons. First, because the working distance is close, our eyes have to exert extra effort to make details clear. This is called “accommodation.” Adults over 40 are no longer able to do this, and need to wear reading glasses or multifocal lenses to read comfortably up close. While children and young adults are still able to accommodate to make things clear, doing so for long periods of time is fatiguing. Often, we see young patients in the clinic who spend so much time on devices that their eyes’ focus is effectively “stuck” up close, and their distance vision is blurry as a consequence. Our eyes also have to converge, or turn together, to point up close. Doing so allows us to view different distances without seeing double. This is a normal phenomenon, and should happen automatically and effortlessly. However, sustained convergence without breaks can become an uncomfortable chore. When our eyes are no longer able to sustain this position, they tend to relax to their normal, straight alignment. This causes double vision; which can be resolved by either turning one eye off, or exerting increasing amounts of effort to keep the eyes aligned, neither of which are desirable outcomes.
The type and amount of light emitted from screens also has adverse effects on the visual system. High energy light causes overstimulation of the senses and can disrupt sleep patterns, alter moods, and cause visual fatigue. It’s hard to imagine a child drifting calmly to sleep after an intense session playing Fortnite. While devices and electronics may be entertaining and exciting, they offer little to promote creativity and provoke meaningful thought.
A recent study linked the use of smartphones with an eye turn toward the nose, or esotropia. The researchers in this study found that excessive smart phone use can influence the new development of an eye turn in children with previously normal vision. They also noted that upon refraining from electronics, the eye turn always improved, sometimes resolving completely without any other interventions at all.
While looking at how near work affects refractive errors (glasses prescriptions), a group of researchers compared over 500 children who attended different schools. The students attending one school were encouraged to play outside every day during recess, while students at the other school had indoor activities during their breaks. After one year of differing recess patterns, the children who were kept indoors had either become myopic (nearsighted), or increased in myopia at much higher rates than their counterparts who had regular outdoor activities. They concluded that excessive indoor and near visual tasks have a profound effect on myopic shift, or the amount of increase of nearsightedness over time.
Due to the abundance of evidence about the potentially poor consequences that screen time and excessive near activities have with regard to vision, children should be encouraged to spend more time playing outdoors and with hands-on games that promote healthy development.