Surgery for refractive errors

[Tariq Zaki]

Surgical and laser procedures (refractive surgery) can be used to correct the refractive errors nearsightedness, farsightedness, and astigmatism. These procedures are commonly used to reshape the cornea so that it is better able to focus light on the retina. Another type of refractive surgery for people who have severe nearsightedness involves insertion of a thin lens inside the eye.
The goal of refractive surgery is to decrease dependence on eyeglasses or contact lenses. Before deciding on such a procedure, people should have a thorough discussion with an ophthalmologist (a medical doctor who specializes in the evaluation and treatment [surgical and nonsurgical] of eye disorders) and should carefully consider their own needs and expectations, along with the risks and benefits.
The best candidates for refractive surgery are healthy people aged 18 and older with healthy eyes who are not satisfied with eyeglasses or contact lenses and who enjoy activities, such as swimming or skiing, which are difficult to do with eyeglasses or contact lenses. Many people undergo this surgery for convenience and cosmetic purposes. However, refractive surgery is not recommended for all people with refractive errors.
People who usually should not have refractive surgery include those who have

A change in their eyeglass or contact lens prescription in the past year
Conditions that impair wound healing, such as autoimmune or connective tissue diseases
Active eye disease such as severe dry eye
Keratoconus (cone-shaped corneas)
A recurrent herpes simplex infection involving the cornea

Additional people who usually should not have refractive surgery are those who are

Taking certain drugs (for example, isotretinoin or amiodarone )
Younger than 18 (with a few exceptions)

The doctor determines the exact refractive error (eyeglass prescription) before surgery. The eyes are thoroughly examined, and special attention is paid to the surface cells of the cornea (including whether the cornea has a loose or well-anchored surface layer), the shape and thickness of the cornea (using tests called topography, tomography, and pachymetry), the pupil size, the intraocular pressure, the optic nerve, and the retina.
Refractive surgical procedures are generally brief and cause little discomfort. Eye drops are used to numb the eye. Because the eye is not held still, the person should try not to move the eye during the procedure. Usually, a person can go home soon after the procedure.
After refractive surgery, most people have distance vision that is good enough to do most things well (for example, driving or going to the movies), although not everyone has perfect 20/20 vision without eyeglasses after the procedure. More than 95% of people do not need corrective lenses for distance vision. The people most likely to have 20/20 distance vision after surgery are those who have mild to moderate eyeglass prescriptions before refractive surgery. Even if they do not wear eyeglasses for distance vision, most people older than 40 still need to wear eyeglasses for reading after refractive surgery.
Side effects of refractive surgery include temporary symptoms of

Feeling as though something is in the eye (foreign body sensation)
Glare and halos around lights
Dryness

Occasionally, these symptoms do not go away. Dryness can cause vision to blur.
Possible complications of refractive surgery may include

Overcorrection
Undercorrection
Infection

It is important to have high-quality surgery with an experienced refractive surgeon to minimize complications.