Eyes and iPads make the facts easy to read

In early 2010, Apple CEO Steve Jobs released the world's first tablet computer - the iPad. Since that moment iPads have swept the world like a tide and are now in the hands of people of all ages. With tablet computers and smartphones have come electronic games, puzzles, videos and pre-school applications that have captured the hearts and eyes of children. Can you blame parents for worrying whether their children's vision will be affected?

Do electronic screens cause near-sightedness?

First, let's talk about the tablet computer's connection to myopia (nearsightedness). Scientists have produced no conclusive findings about this connection. In recent years, several studies have shown that the most important cause of myopia is genetics. If both parents are myopic, the child is four times more likely to be nearsighted. If one parent is myopic, the child is twice as likely to be nearsighted.

Myopia has gradually become more prevalent around the world. A British study found that in addition to educational level, socioeconomic status and genes, another factor that affects vision is if your mother was older or smoking when pregnant or if you experienced growth delays in the womb.

Many parents worry that their children will harm their eyes by watching TV or playing on the computer too much. To date, there has not been a rigorous investigation into this. The fact is that anything you visually focus on and put close to your eyes - whether books, television, computers, art - will cause the eyes to tire and eventually become fatigued.

The biology of myopia

When we start focusing our vision closer and closer to our noses, our lines of sight converge and the part of our eyes called the lens starts to lose its original shape. These processes are involuntary but inevitable if you force your eyes to focus for a long time without relaxing.

Sometimes, people can develop "pseudo-myopia" where you become nearsighted for a short period of time after a long period of focusing on one thing. This happens because the eye muscles become fatigued and this causes your eyes to be temporarily incapable of lining up the information each eye receives. If we get too engrossed in a TV show or a computer program, we are preventing our eyes from relaxing.

How much screen time is appropriate?

After learning that electronic screens themselves do not have a direct impact on vision (it's time and distance, not the screen itself), parents started asking the next question: how much time should I allow my child to watch TV or play on the computer for? There's no standard answer to this. Vision and visual development depends on genes, the child's environment, stress, outdoor activities and a host of other things. How much time each child can spend looking at a screen without impairing their vision is difficult to generalize. Parents need to exercise discretion in managing their child's visual habits. As an ophthalmologist, my suggestion is to encourage children to participate in outdoor activities. These are good for kids and are fairly visually harmless.

Alleviating eye strain

IPads and e-books have special display technology that simulates real ink or that automatically adjusts the screen's brightness according to ambient light. To a certain extent this technology can help reduce eye strain while reading.

However, there are certain measures parents can encourage their children to take to alleviate visual fatigue and prevent myopia. For example, they can suggest doing some eye massages by pressing on pressure points around the eye. In order to relax the eye muscles, every 20 minutes spent on a computer should be rewarded with a 20 second break during which children focus on something five or more meters away. The height of the screen also needs to be adjusted, alongside the brightness of the screen.

Visiting the eye doctor

Finally, I would like to remind parents to bring their children in for an eye checkup every six months. School children have a heavier academic burden, so spend more time staring at things close to their noses. Six months is a good amount of time to check for visual acuity and any visual conditions that might have developed since the last eye exam.

　　Chen Sherry MD PhD

Ophthalmologist

Dr Sherry Chen is from China. She completed her bachelor's and master's degree in medicine at Beijing Medical University. She earned her PhD degree from Peking University Medical School.

Chen completed her residency training at The Third School of Clinical Medicine at Beijing Medical University. She completed her specialized fellowship training in ophthalmic pathology in the Department of Pathology at the University of Illinois (Chicago), where she worked under Professor Robert Folberg.

After working at the University of Illinois, Chen returned to China to work as an ophthalmologist and ophthalmologic pathologist at the Peking University Eye Center. During her nine years there, she spent some time doing cataract surgery with the Lifeline Express program in Qinghai Province. She eventually rose to the position of Chief Executive Attending Doctor.

Chen speaks English and Chinese.