Curvature Analysis
Astigmatism occurs when parts of the eye (cornea, lens or the clear cover in the front of the eye) are abnormally curved, causing light to focus improperly on the retina (the part of the eye that converts images and light into brain signals). This causes blurred vision. Before astigmatism can be corrected, the abnormal curvature must be measured using a keratometer, which measures light reflected off of the cornea, or a keratoscope, which measures the spacing and reflection of light rings projected on the cornea. Often these devices are fitted with a video camera so that the measurements can be recorded and carefully reviewed.
Corrective Lenses
One way of treating astigmatism is through the use of corrective lenses designed to counteract the abnormal curvature of the cornea. These lenses focus light beams properly onto the retina. Corrective lenses can come in the form of contact lenses (both hard and soft) as well as special eyeglasses. These kinds of corrective lenses work best when the patient's vision is otherwise mostly unimpaired, although patients who also need bifocals (for nearsightedness and farsightedness) can get bifocal lenses for astigmatism.
Refractive Treatments
Another way to treat astigmatism is to surgically correct the eye's curvature. The most commonly used curvature-correcting treatments are performed using lasers and include LASIK eye surgery. In this procedure, a small flap of the cornea is cut and peeled back while an excimer laser (a non-heat-generating laser) reshapes the cornea to give it the correct shape. There are many different kinds of refractive laser surgery, but they primarily differ in how large of a corneal flap is peeled back before using the laser on the eye.
