Astigmatism
Astigmatism is a difficult concept to understand.
Under normal circumstances an eye that is looking at say a star in the night sky will see a single point image of that star. A person with astigmatism however will see a halo around it or even a blurred image of the star. This is because two, not one image of the star is formed by the eye. One image is front of the other within the eye. This arises from either the shape of the cornea (the front of the eye) being an oval rather than round shape or the lens having an unusual shape. In most cases it is both. Thus the flatter meridian of the cornea produces an image on the back of the eye and the steeper meridian produces a second image in front of it
Astigmatism is a difficult concept to understand.
Under normal circumstances an eye that is looking at say a star in the night sky will see a single point image of that star. A person with astigmatism however will see a halo around it or even a blurred image of the star. This is because two, not one image of the star is formed by the eye. One image is front of the other within the eye. This arises from either the shape of the cornea (the front of the eye) being an oval rather than round shape or the lens having an unusual shape. In most cases it is both. Thus the flatter meridian of the cornea produces an image on the back of the eye and the steeper meridian produces a second image in front of it
This drawing shows two images. one in red and a second image in blue which is in front of the red one.
The consequences of astigmatism specially large amounts, is blurry images.
Most people have some degree of astigmatism but not usually enough to cause blur.
Having astigmatism does not mean that is anything wrong with the eye, merely that is greater than normal to the point of blurring vision.
Correcting Astigmatism with Lasik or PRK
Astigmatism is corrected during laser vision correction by the laser which can correct up to 5 diopters.
Correcting Astigmatism during cataract surgery
Correcting astigmatism during cataract surgery or clear lens extraction is more involved than during laser vision correction with Lasik.
There are essentially two ways to do this. The first is using a Toric lens which is lens with two focal points. The second is the use of limbal relaxing incisions in which the shape of the cornea is altered at the time of surgery using a special blade
The consequences of astigmatism specially large amounts, is blurry images.
Most people have some degree of astigmatism but not usually enough to cause blur.
Having astigmatism does not mean that is anything wrong with the eye, merely that is greater than normal to the point of blurring vision.
Correcting Astigmatism with Lasik or PRK
Astigmatism is corrected during laser vision correction by the laser which can correct up to 5 diopters.
Correcting Astigmatism during cataract surgery
Correcting astigmatism during cataract surgery or clear lens extraction is more involved than during laser vision correction with Lasik.
There are essentially two ways to do this. The first is using a Toric lens which is lens with two focal points. The second is the use of limbal relaxing incisions in which the shape of the cornea is altered at the time of surgery using a special blade
