Eyes and iPads

In early 2010, Apple CEO Steve Jobs released the world’s first tablet PC – the iPad. This spring, Apple will release the third generation of iPads, which are sweeping the world like a tide and putting an “Apple” in the hands of people of all ages. With tablet computers and smartphones came 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 (near-sightedness). 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 near-sighted. If one parent is myopic, the child is twice as likely to be near-sighted. 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 how or whether computer or TV screens impact vision. The fact is that anything you visually focus on and put close to your eyes – whether books, television, computers, art, even embroidery – will cause the eyes to tire and eventually become fatigued. Anything held and focused on within 50 cm of our eyes tires them. To rest our eyes, it is best to focus on and hold objects more than 50 cm away from our eyes.

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 use your eye muscles to force your eyes to focus for a long time without relaxing. Sometimes, people can develop “pseudo-myopia” where you become near-sighted 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.

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. We can also use the following approaches to alleviate visual fatigue and prevent myopia:

1. Try doing some eye massages by pressing on pressure points around the eye. Most Chinese students could show you how to do an eye massage.
2. Relax the eye muscles. Every 20 minutes spent on a computer should be rewarded with a 20-second break during which you focus on something 5 or more meters away.
3. Adjust the height of the screen so that it is 5-40 degrees below eye level.
4. Adjust the brightness of the screen so that it does not contrast too much with the environmental brightness around you.
5. Make yourself blink periodically.
6. Adjust text on your computer so that your eyes feel comfortable when you read.
7. If you need to, wear progressive lenses for focusing on objects at various distances.

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? There’s no standard answer for this question. 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 his/her vision is difficult to generalize. Parents need to exercise discretion in managing their child’s vision and 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.

Visiting the eye doctor

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