General Eye Conditions
Common eye conditions which cause people to wear spectacles or contact lenses are called refractive errors. Common types of refractive errors include myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
LASIK and PRK LASER eye surgery can change the shape and curve of the cornea to correct or reduce these types of refractive errors.
20/20 Vision
20/20 is a measurement of your distance vision.
20/20 vision is frequently described as a person being able to see detail from 20 feet away that a person with normal vision can see from 20 feet.
Therefore, if a person has a 20/40 vision, this indicates that the person would have to be 20 feet away to be able to see what a person with normal vision of 20/20 could see at 40 feet.
Astigmatism
If the cornea (the transparent front surface of the eye) is not regularly shaped, the image formed on the retina is blurred both for distance and up close.
A perfect cornea is completely spherical, but with astigmatism the cornea has a steeper curvature in certain axes, called "corneal astigmatism".
