Over 120 million people in the United States wear eyeglasses or contact lenses to correct refractive errors, such as nearsightedness, farsightedness, or astigmatism. These vision disorders affect the cornea and are the most common of all vision problems in the United States.
Refractive errors occur when the curve of the cornea is irregularly shaped, either too steep or too flat. When the cornea is correctly shaped, it bends, or refracts light on the retina with precision. However, when the curve of the cornea is irregularly shaped, the cornea bends light imperfectly on the retina. This has a negative affect on your vision.