Etiology - An astigmatism is caused by an uneven curvature of either the cornea or lens of the eye. In most, cases it's the cornea that is misshapen. An astigmatism can be present at birth, induced by an injury/surgery, or developed simply due to aging.
Symptoms - Blurry or distorted vision, decreased night vision, squinting, eye strain, and headaches.
Details - An astigmatism creates an uneven focus of light on the retina, which in turn decreases the overall quality of vision. Oftentimes, it's accompanied by nearsightedness (myopia) or farsightedness (hyperopia).
Treatment - An astigmatism isn't "curable" per say, but it can certainly be corrected. The two most common treatment approaches are prescription glasses/contacts or LASIK surgery.
Visual representation of how light reflects in an eye with vs without an astigmatism.
Photo Creds: Cleveland Clinic