Simple eye conditions
The eye is a precise image capturing device that relies on an image being formed on the retina by the focussing of light rays through the cornea and fine tuned by the internal lens. Given that the tolerances for good vision are extremely small and that these rely on the correct focussing power given the axial length of the eye all of which one would expect to be as variable as the size of any other part of our body it is a small miracle that many of us need no correction until in later life. When such a perfect fit is not present we end up with a need for optical correction.
Here are some common examples of blurred vision created by slight imperfections of our most valuable sense organ:
