Sometimes I cannot see an object very clearly because my eyes don’t focus on it, no matter how much I try, why is this?

Question: Sometimes I cannot see an object very clearly because my eyes don't focus on it, no matter how much I try, why is this?

Asked by amohamed to Lily on 16 Jun 2010 in Categories: General.
- Lily Asquith answered on 16 Jun 2010:
  
  Your iris (the coloured bit of your eye) is muscle. You focus on an object by using this muscle to squeeze or stretch the lens in your eye until the object you are looking at comes into focus.
  
  If your eye is trying to focus on something very close to you the lens is being squeezed so that it gets more like a sphere than a disk. There is a limit to how far this can go.
  
  If the lens in your eye was more flexible you could see very close/far objects.
  
  If you can’t see objects clearly even though they are 30cm away from you then you might have a problem with your eyes.
  
  They could be tired (then the iris muscle wants a rest) or you could have something going on with the shape of the lens in your eye which could be fixed with glasses.

Question: Sometimes I cannot see an object very clearly because my eyes don't focus on it, no matter how much I try, why is this?