Having normal vision simply means that your eye is correctly shaped, allowing light to focus directly on your retina, thus giving you a clear image. This condition wherein the eye requires absolutely no correction is sometimes referred to as emmetropia. To understand how LASIK works, you first need to know a little about common vision problems.
Nearsightedness: This means that your eye is too long or your cornea is too steep, causing light to focus in front of the retina and making distant objects appear blurry.
Farsightedness: This means that your eye is too short or your cornea is too flat, causing light to focus behind the retina and making near objects appear blurry.
Astigmatism: This means that you have an irregular cornea or lens, causing images both near and far to be distorted or blurry.
Presbyopia: This is a common age-related problem that is caused when the natural lens in the eye loses its elasticity, making it difficult to focus on near objects.