Astigmatism is a common eye condition characterized by an irregular curvature of the cornea. This type of disorder is also known as a refractive error, and differs from myopia (nearsightedness), hyperopia (farsightedness), and presbyopia (the inability to focus on near objects and read up close after age forty).
A person’s eye is naturally spherical in shape. Under normal circumstances, when light enters the eye, it refracts evenly, creating a clear view of the object. However, the eye of a person with astigmatism is shaped more like a football or the back of a spoon. For this person, when light enters the eye it is refracted more in one direction than the other, allowing only part of the object to be in focus at one time. Objects at any distance can appear blurry and wavy.
Astigmatism occurs in nearly everybody to some degree, but for significantly abnormal curvature, treatment is required. Astigmatism can be surgically corrected separately or at the time of cataract surgery with astigmatic keratotomy (AK) or with the implantation of a toric intraocular lens. It is also routinely corrected during laser vision correction surgery using the excimer laser when performing LASIK or PRK.
As cataract surgery evolves now and in the future, more cataract patients are having their astigmatism corrected with Femtosecond Laser-assisted surgical techniques.
Astigmatic Keratotomy (AK):
This procedure is usually done at the beginning of a cataract operation and involves making one or two additional incisions in the cornea at its steep axis to create a more spherical surface shape out of a previously football shaped cornea. About 40% of cataract patients have a large enough amount of astigmatism to benefit from AK astigmatism correction. For these patients, it is either: 1) fix the astigmatism, or 2) wear glasses after cataract surgery.
Another method to surgically treat astigmatism involves the implantation of a toric IOL at the time of cataract surgery. Both toric IOLs and AK (one with a laser or manually with incisions) work well, although in some circumstances one astigmatism correction option may trump the other. Talk to your Premier Medical Eye Doctor about your specific needs and options.