Children are back in school, which means not just more time with books, but more time with computers — and parents should be mindful of possible digital eyestrain.

“Kids are exposed to screens at home and at school — that’s inevitable,” said Dr. Steven Rhee, medical director at Hawaiian Eye Center. “We should be aware, though, that prolonged screen time can cause eye symptoms such as eye strain, dry eye and even headaches.”

Such symptoms are usually temporary, but they may be frequent and persistent, according to the American Academy of Ophthalmology. Children need to take constant breaks when using computers and other digital devices because they don’t blink as often while doing so, as well as while doing extended reading, writing or other intensive “near work.”

“I recommend following the 20/20/20 rule: After 20 minutes of screen time, look far off in the distance at least 20 feet away for about 20 seconds,” Rhee said.

That helps to reset and relax your eyes to prevent eye strain, he said.

“Studies have shown that prolonged ‘near work,’ such as staring at a screen or reading, may promote the development of nearsightedness or myopia,” he said. “That’s another good reason to follow the 20/20/20 rule to prevent eye strain — and to get your kids outside more.”

There are preventative measures parents and their children can take to avoid eye strain, all of which can be discussed with your family eye doctor, Rhee said.

Here are more tips from the American Academy of Ophthalmology and Hawaiian Eye Center to help protect your child’s eyes from computer eyestrain:

>> Set a kitchen timer or a smart device timer to remind children of the 20/20/20 rule.

>> Tell your child to use good posture when using a computer and when reading.

>> Avoid having your child use a computer outside or in brightly lit areas, as the glare on the screen can create strain.

>> Adjust the brightness and contrast of your child’s computer screen so that it feels comfortable to them.

>> Alternate reading an e-book with a real book and encourage kids to look up and out the window every two chapters.

>> Pre-mark books with a paperclip every few chapters to remind your child to look up. On an e-book, use the “bookmark” function for the same effect.

>> After your child completes a level in a video game, have him or her look out the window for 20 seconds.

>> Encourage your child to hold digital media farther away; 18 to 24 inches is ideal.

>> Remind children to blink when watching a screen.