For a long time of focusing your vision on the nearby computer screen, the lens of your eyes would be made convex for as long a time. When you need to focus your vision on near objects, the lens become more convex so as to refract light coming from nearby objects onto the retina clearly.
When you look at distant objects after prolonged period of computer use, your eyes have to readapt by relaxing the ciliary muscles that control the thickness (hence curvature) of your eye lens. Since there is a prolonged period where the muscles applied force to focus on near objects, the muscles relax gradually and not instantly. Thus vision is blurry at first when you focus on far objects immediately after computer use. Very soon after your lens will be able to focus the distant objects clearly onto your retina, and things do not look blurry.
One case where distant objects do not become clear even if you try to focus on far objects is short-sightedness, also resulted from computer usage. It is because you use too much time focusing on the computer screen that your lens become too convex. This means that even if your ciliary muscles relax, the lens would not be able to focus on far objects by being less convex. The lens become more convex than it was when you were born. Hence you would be more able to focus on short objects, as a result of the more convex lens, and you have "short-sightedness". Far objects on the other hand always look blurry.
If you work in front of a computer all day, or spend a lot of time watching TV and playing video games, you might have noticed your eyesight getting a bit blurry. This is due to a condition known as Computer Vision Syndrome (CVS), a group of eye and vision-related issues that are the result of too much screen time. The good news is CVS is not permanent and there are many things you can do to help prevent it. Computers put excess strain on the visual system. The lack of definition of the letters on the screen, the reduced level of contrast, and the reflections on the glass all make viewing more difficult. Poor posture, bad lighting, viewing distance, and screen resolution also worsen symptoms.
Many of us spend hours in front of a computer screen every day, and that can take a toll on your vision. Generally speaking, viewing objects farther away from us is easier on our eyes; conversely, the muscles in our eyes must work harder to view things at close range. Staring at a computer screen for long periods of time, therefore, can cause you to strain the muscles in your eyes and may result in headaches, blurred vision and eye fatigue.There are changes you can make that may help relieve many computer-related vision problems, such as improving lighting in the work area, altering the workstation height, taking intermittent breaks, or obtaining prescription glasses for computer use.