On this page we will go over three basic abnormalities. We will start with normal vision and then discuss nearsightedness, farsightedness, and astigmatism.
To see how these vision problems can be corrected with glasses, click below:
Glasses
To see how a person with one of these vision conditions would see, click on the link below:
Normal Vision
In a normal eye, the light enters the eye, and is focused by the lens at a point on the back of the eye (retina).
When an eye is nearsighted (myopic), the focal point falls short of the retina, therefore images far away are seen unclearly. The eye is unable to focus because the curvature of the front of the eye (cornea) is more rounded than usual, causing the light to bend unusually. In some situations the eye is elongated, allowing the focal point to be in front of the retina.
An eye with farsightedness (hyperopia) has the reverse problem as nearsightedness. Either it has a flattened cornea, or the eye is somewhat shorter than normal. This causes the focal point to extend behind the retina, making objects up close seem unclear.
Astigmatism is an abnormality in which the eye is both nearsighted and farsighted. This makes it so that all objects, up close or far away, appear out of focus. An oddly shaped cornea is the reason for this problem.