I see a line in my peripheral vision - what is it?

Question

e.g. when I look at the computer screen a horizontal line is in my peripheral vision? what could it be?

Answer 1

This could be a scratch on your sclera/cornea, or it could be because of glaucoma (when you peripheral vision starts to fade until you have a very narrow line of sight). You should consult your doctor, and ask if they test for glaucoma, because where I live, most doctors don't test everything.

Does this only happen when you look at the computer screen? If so, it might be because you look at it so long that when you look away the light from the screen is still being processed in your brain, so you see the light from the screen.