Normal Vision Astigmatic Vision
Astigmatism is the most common vision problem. Astigmatism may accompany nearsightedness or farsightedness. It’s caused by an irregularly shaped cornea. There are two kinds of Astigmatism, lenticular and corneal. Astigmatism occurs when the surface of the cornea or of the lens is not perfectly smooth. If, for example, there is a small flat spot on your cornea the image in a certain direction on your retina will not be in perfect focus.
If the figure on the right was constructed with all the radial lines of equal sharpness and contrast a person without Astigmatism would see all these radial lines as perfectly sharp and with the same contrast. The diagram on the right has been fudged to illustrate how it might appear to a person with Astigmatism.
Astigmatism Symptoms and Signs
If you have only a small amount of Astigmatism, you may not notice it or have just slightly blurred vision. Sometimes uncorrected Astigmatism can give you headaches or eyestrain, and distort or blur your vision at all distances.
It’s not only adults who can be Astigmatic. It has been found in a recent study that more than 28 percent of them had astigmatism. Children may be even more unaware of the condition than adults, and they are unlikely to complain of the blurred or distorted vision. Unfortunately, Astigmatism can affect their ability to see well in school and during sports, so it’s important to have their eyes examined at regular intervals in order to detect any Astigmatism early on.
What Causes Astigmatism?
Astigmatism occurs when the cornea is shaped more like an oblong football than a spherical baseball, which is the normal shape. The oblong shape causes light rays to focus on two points in the back of your eye, rather than on just one. Many people are born with this oblong cornea, and the resulting vision problem may get worse over time.