As far as I'm aware, the eye acts like a pinhole camera in that it inverts the image on the rentina. This makes sense as the rays converge and form a focal point that is upside down.
Myopia (shortsightedness) is described as the rays focusing before the retina, resulting in a blurred distance image. This would still be the right side up. However with Hypermetropia (farsightedness) the focal would be behind the retina, so the rays should project a blurry but right side up (but interpreted by the brain as upside down) image.
I know this is not the case, by why?
Best Answer
The eye does not act as a pinhole camera. It is a multi element optical system with the cornea and inter-ocular lens doing most of the work. An image is inverted because the light entering the eye from above is headed DOWN, below the optical axis and will therefore image on the lower half of the retina. The light coming from below is has a positive slope and will image on the top half of the retina. This has nothing to do with focus. Regardless of where your image plane is (retina), the converging cones of light are still headed up or down depending on where they came from in object space. While walking on the sidewalk, the light from the gum you're about to step in is headed UP towards your eye and will image on the upper half of the retina. The light from the bird nest that is about to hit you is coming down to you from above and will continue that trajectory even as it passes through the lens in your eye. This has nothing to do with focus.