Скачать или смотреть Computer vision syndrome ( Causes & risk factors,Symptoms,Treatment )

Extensive use of digital devices causes computer vision syndrome. Some research shows that continuous screen use for at least two hours can be enough to trigger symptoms. The longer you spend staring at screens, the more likely you are to develop symptoms.

The screens themselves aren’t fully to blame. Spending a long time focusing on close-up objects can strain your eyes, whether you’re looking at a screen or a printed page. But the screens add another layer of strain to your eyes. Here’s why:

Constant refocusing. When you use screens, you have to constantly focus and refocus to see the print (which is made of pixels, or tiny dots). Constantly moving your eyes in this way can strain them.
Screen contrast levels. Often, there’s a low contrast level between the letters you read on a screen and their background. This can make your eyes work harder.
Inadequate blinking. Normally, you naturally blink about 18 to 22 times per minute. You need to blink enough to keep your eyes lubricated. But when using a computer, most people only blink three to seven times per minute. Screen use may also cause incomplete blinking. This means you only partly close your eye when you blink. Not blinking fully or often enough can cause the surface of your eyes to dry out.