the technical term for this in me is called computer vision syndrome. aka eye strain due to computer usage.

short version because of the way computers work the eyes are constantly being stimulated to move back and forth, up and down at a much higher rate which causes the eye muscles to get stressed and strained which causes the eye to have less focusing ability, and the pupils are constantly contracting (getting bigger and smaller) based on lighting factors, colors brightness and contrast of text against various backgrounds.

treatment I am on for it is spending less time on the computer, wearing special glasses that filter out the harmful blue lighting and having my computer settings set at a comfortable level for my eyes, more mono toned shades instead of vibrant and bright. (example instead of using the bright "spring" theme here on my support forum I am using the more plain less contrasting colored theme "psych central")

since its your medicine that is causing the problem and many meds cause a situation called photosensitivity you might want to talk with your treatment provider to see if this is the cause for your eye strain aka blurry vision while on the computer.