A flaw in the curvature of the cornea (the clear covering at the front of the eye structure) or the lens can occur naturally, even from birth. When the cornea is irregularly shaped, the eye does not have the capacity to focus correctly. Ideally, a lens with no defects reflects light to a single point on the back of the eye, on the retina. An unnatural curve causes a problem in the reflective process, and light is not focused to one point.
This causes a variety of symptoms, including:
Blurred vision Eyestrain
Headaches Frequent squinting
Difficulty with night vision Double vision
Astigmatism can occur at any age, and can worsen over time. If you are nearsighted or farsighted, it is important that your eyes are checked for astigmatism as the condition may not be corrected with your current eyeglass or contacts prescription.