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Asked by ellascientist to clairemarieroberts, Faye, Martin, Mus, Pete on 24 Apr 2012.
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Pete Etchells answered on 24 Apr 2012:
Hi ellascientist, that’s a great question! My PhD was on how and why we move our eyes, so hopefully I know the answer to this one. At the back of your eye, you have lots of cells called ‘photoreceptors’, which detect light that comes through the lens, and converts it into an electrical signal that is then passed on as information for the brain. All of these signals have to come out of your eye, so there’s an area at the back of your eye where the optic nerve starts, and all the information is sent along there. Because there aren’t any photoreceptors where the optic nerve starts, you can’t see anything in that particular part of your vision – hence, the blind spot!
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Comments
ellascientist commented on :
I read that becasue you have a blind spot in each eye it makes up for the blind spot in the other eye and so you have no gaps in your sight, is this true?
Pete commented on :
You can test this yourself! If you close one eye, do you suddenly have a bit of a gap in your vision, or not?
ellascientist commented on :
I can’t find a gap when I’m just closing one eye. But, when there are two dots and close one eye and I focus on one of them the other disappears.
Pete commented on :
Great! So technically, there is a gap in your vision – because when you look at the dots, you can’t see one of them. But if you just look around normally when you have one eye closed, it doesn’t seem like there’s a hole anywhere, does it? That’s because our brain basically ignores the fact that it can’t really see anything in that region, and uses very tiny eye movements to fill in the gaps!
spacenut commented on :
Neither can I?