What is astigmatism?

Astigmatism is a common visual problem affecting 200 million American in the U.S.  A normal cornea should be spherical in shape, so that incoming light can converge into one single focus.  For those that is suffering from astigmatism, their cornea is not spherical but oval in shape.  One of the meridian is longer than the other, as a result, light does not converge into one single focus, but into two major focal points,  due to the two different meridians.  People who suffer from astigmatism generally complain of blurred vision at distance and near, especially in dim light environment.

Astigmatism and contact lenses.

In the past, patients suffering from astigmatism would have to wear glasses or rigid contact lenses.  However, with the advancement of technology, there are many more choices for astigmat than before.  In a fitting session, Dr. Pang will measure the shape of your cornea with a instrument called topographer, depending on the shape of your cornea, he will try different types of contact lenses on your cornea in order to determine a design which will provide you the best vision and comfort.  These lenses are specially designed to correct your uneven corneal shape.  They are called toric lenses, there are two major designs in toric lenses.  One of them uses additional weight at the bottom to stabilize the lens, and places two different powers on the front surface of the lens to correct the astigmatism.  The other design thins out the edges of the lens at 3 and 9 o’clock position to stabilize the lens, and the astigmatic power is placed at the front surface of the lens.

Either one of these designs provides excellent vision to their wearers.  Some patients are more suitable to use one design than the others, it is largely determined by the lids interaction or the shape of your eyes.  It is hard to predict which type of contact lenses is best suited for you, call us for a consultation and receive a free trial pair of contact lenses.