The American Optometric Association recommends following the 20-20-20 rule to alleviate eye strain, by taking a 20 second break every 20 minutes to look at something 20 feet away.

美国验光协会建议遵循20-20-20原则来缓解眼睛疲劳，原则就是每隔20分钟休息20秒，看看20英尺以外的东西。