Astigmatism
Doc? I was told that I have one of those 'stigmatisms. Am I going blind?
Its funny how often I get asked this question--the usage of the word implying that a-stigmatism is some sort of object or disease to be feared. I'm not casting dispersions on my patients, the word has a horrible ring to it and conjures up negative images when its root, STIGMA crosses the palate. Lets start with the word itself. ASTIGMATISM is one word, not two. And it describes a type of refractive error in the eye that causes blurry vision.
What is ASTIGMATISM?
Astigmatism describes the way light is focused through cylindrical optics--in this case, the optics being the lenses in your eye. Eyes with astigmatism have oblong lenses (shaped like a football) that break the focus apart into two separate points. In contrast, eyes without astigmatism are perfectly spherical (like a baseball), and they focus light to a single point.
How Does Astigmatism affect vision?
Eyes with astigmatism focus incoming light onto the retina in fun house-mirrorfashion. How a person sees with astigmatism depends on the amount of astigmatism and the axis of its alignment. The more one has, the more distorted the vision will be, and astigmatism frequently causes eyestrain-based head aches. In fact, small amounts of astigmatism that don't cause noticeable blur can stimulate the eye's accommodative (focus) mechanism into a spasmodic attempt to clear the physical blur--which it can not do with a split focus--causing a head ache. It can also cause one to see double and ghost images.
How do I tell if I have Astigmatism?
Blurry vision, head aches, eyestrain, or difficulty focusing objects at any distance may be signs of astigmatism. Astigmatism is easily found and corrected at regular eye exams. Observe the diagram below with un-corrected vision one eye at a time; and if you have astigmatism, you will probably notice some of the lines focus more clearly than the rest. The more astigmatism you have, the more you will notice it. Conversely, small amounts may not be readily apparent.
Correcting Astigmatism
Astigmatism is easily corrected by glasses, contact lenses (Soft Torics and Gas Permeable), and with surgery. Because astigmatism is a little unpredictable, you may find that your correction needs to be updated over time to maintain best vision. The lenses we use to correct astigmatism are cylindrical in shape--neutralizing your cylindrical error with the opposite cylindrical shape.
