Why do some people see lines after reading?

[AquilaRising]

I've noticed that some people complain about this and I've often wondered whether it's normal or a symptom of something like palinopsia.  I see them sometimes too, if I read something for about 5 minutes on the computer or even in real life, I'll see lines in my vision, they're usually pale and transparent and show up if I look at something white.  My mom sees them too, and so do a few of my friends, but not all.  Reading with sunglasses or in dim light with less contrast eliminates them. Can anyone give me some insight into this?  Thanks.

[Doreen Fazio, M.D.]

What you and the others are experiencing is most likely normal and is common after computer use.  These after-images fade quickly and do not harm the eye.

[AquilaRising]

That's interesting, but in some cases, the bars seem to stay in people's vision for longer than a few seconds.  In my mother's case they can last for up to 40 seconds if she gets stuck on a page that she reads up close for more than 3 minutes.  The bars just hover in her vision and she can watch them on the ceiling for a while until they fade. It's the worst in high contrast situations, and it can happen on the computer or with books if she reads in dim light by a bright lamp.  I know about the blind spot phenomenon, it's really fascinating too. Thanks for the input!

[erocked]

Its an optical illusion.  Find any black and white image and focus on a small portion of it for a minute or so.  Then look at a white wall. the image will appear on the wall for a few seconds as if it were burned into your vision..  Reading black text on white paper does the same thing.  The lines are because your eyes are moving across the line of text.  Its very interesting to me because it shows that humans do not see a direct representation of reality, but rather a translation formed by your eyes and mind.  Another cool one is blind spots.  Place 2 pennies on a table about 3 inches apart.  Stand up and look down at the pennies and cover just your right eye.  Focus on the penny on teh right and move your head closer and closer to that penny until the penny on the left completely disappears.  That is your blind spot, which is the spot in your eye where the optical nerve connects the retina to your brain.  It does not detect light.  Never has and never will.  But your mind just fills the space with whatever is around it.