Vision Problems Defined

Myopia (nearsightedness)

The most common refractive condition, myopia, affects one in four people. If you have this condition, either your cornea is too curved for the length of your eye or the eye is too long for your cornea. This causes the rays of light that enter your eyes to focus in front of the retina, resulting in clearer near-vision and blurrier distance-vision. Refractive surgery helps correct nearsightedness by flattening the cornea, so light can bend to a more perfect point on the retina, resulting in clearer distance-vision.

Hyperopia (farsightedness)

Farsighted people have corneas that are too flat, so images are focused behind the retina, distorting their near-vision. During refractive surgery the cornea is made steeper, pushing the focal point back to a point directly on the retina.

Astigmatism

If you have astigmatism you have an unevenly shaped cornea or eye that causes light rays to separate and focus at various points on the retina, producing a "ghost-like" or "fuzzy" image. Astigmatism can occur by itself, however, it doesn't discriminate between myopia or hyperopia either. In can occur in a combination of either two -- but all are correctable with the right kind of refractive surgery.

Presbyopia

Almost everyone who hits the 45-year mark experiences presbyopia -- the degradation of vision due to the aging process. The natural weakening of the crystalline lens causes it to lose the ability to focus light from close objects on to the retina. Near-vision is most effected which explains why "presbyopes" hold restaurant menus way out in front of them. Presbyopia is easily fixable with reading glasses, bifocals, contact lenses or even surgery.

Monovision

Monovision is one option to correcting the effects of presbyopia. With glasses, contact lenses or refractive surgery, your dominant eye is set for distance vision and your non-dominant eye is corrected for near. This alternative decreases your dependence on reading glasses but could pose a problem with distance clarity and depth perception. If you're considering refractive surgery, first have your doctor show you some trial lenses or give you a pair of contact lenses to simulate the monovision effect.