US Pharm. 2010;35(4):17-18.
Corrective Procedure to Improve Vision
LASIK (laser-assisted in situ keratomileusis) is a type of eye surgery designed to treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. These conditions, known as refraction errors, are all the result of an out-of-focus image when light is reflected through the cornea onto the retina. LASIK surgery works by changing the shape of the cornea using a laser. Once the cornea is shaped correctly, the eye can focus more clearly and vision improves. The LASIK surgical procedure has been performed on millions of Americans since its FDA approval in 1998, and it continues to be a popular procedure with patients who want to improve their vision.
LASIK is an outpatient surgery that takes less than 30 minutes. The eye is numbed using anesthetic eye drops, and the eyelid is held open by an instrument while a suction ring is placed on the eye to lift, flatten, and hold the cornea steady. A small flap is cut from the corneal tissue and folded back, allowing the laser access to shape the corneal tissue underneath. The flap of tissue is then pressed back into place without stitches. After LASIK surgery is completed, an eye shield is placed over the eye to protect the cornea during the healing period.
LASIK eye surgery is not for everyone. There are many people who should not undergo LASIK, including those with chronic dry eyes, thin corneas, changing refractions, and significant refraction error (very poor vision). Patients considering LASIK surgery must understand the risks and potential complications, as well as the typical results of a successful procedure. For many, LASIK surgery can reduce the need for glasses or contact lenses, but it does not guarantee perfect vision. Even those patients who achieve 20/20 vision with LASIK as measured on the eye chart may not see the sharp images they had expected. In addition, LASIK cannot correct presbyopia, the change in vision that results from aging and requires reading glasses. Many patients who undergo LASIK surgery also find that they require a retreatment (second surgery) to achieve better vision.
Reduces the Need for Glasses or Contact Lenses
Millions of people in the United States have undergone LASIK surgery to improve their vision and become less dependent on corrective lenses (contacts or glasses). Although the majority of patients are pleased with the results, some are disappointed in their visual improvement or suffer permanent side effects or complications from the surgery. It is important to learn about the procedure and identify a surgeon who is skilled in the technique and can determine whether the candidate is likely to benefit from LASIK. Eye doctors who advertise that their patients will “never need glasses again” or make similar promises should be avoided. There are financial considerations as well, since many insurance companies do not reimburse the cost.
Candidates for Surgery
Often people are able to eliminate glasses or contact lenses for everyday tasks after LASIK surgery, although their vision may not be perfect or even as clear as it would be with corrective lenses. The majority of people who have LASIK surgery will have 20/20 to 20/40 vision without glasses or contact lenses. Patients over 40 years of age with presbyopia (problems focusing) will still require reading glasses after LASIK unless they are corrected in one eye for close vision and one eye for distant vision, which is known as monovision. Not all patients adjust well to monovision, so those considering this procedure can try out this correction with a different-strength contact in each eye or different lenses in a pair of glasses.
Some people have conditions that make them ineligible or poor candidates for success with LASIK eye surgery. People with chronically dry eyes, inflammation of the eyelids, thin or damaged corneas, changing refractions, and significant refraction error (very poor vision) are not good candidates for LASIK. Large pupils may also be a problem since halos and glare, two common complaints after LASIK surgery, may be more likely to occur. Pregnant or nursing women or those people taking certain drugs that cause changes in refraction should not undergo LASIK. People with diseases that affect the immune system (e.g., HIV/AIDS, diabetes, lupus) may have trouble with corneal healing after surgery. LASIK is not a good choice for younger people with changing refractions, especially those under age 18 to 21 years.
It is recommended that people considering LASIK discuss their daily work and leisure activities with an eye surgeon when making the decision to undergo surgery. People who need very sharp vision for detailed work or who drive frequently at night may not be satisfied with the results. There is a significant waiting period before vision after LASIK is stable, usually up to 6 months. There are also various waiting periods before wearing eye makeup, swimming, and sports activities can be resumed.
Possible Side Effects
Common complaints after LASIK surgery include scratchy or dry eyes, hazy vision, sensitivity to light, halos or glare, and problems seeing clearly at night. Many of these effects improve over time, although in some people these are permanent. Less typical are problems with visual correction or with the corneal flap that may require a second surgery. Inflammation and infection can occur, but they are usually prevented by the use of prescription eye drops. Rarely, vision is poorer after LASIK, and permanent loss of vision has occurred.
After LASIK surgery, eye drops are prescribed to prevent infection, decrease inflammation and swelling, and soothe dryness. These eye drops must be used as prescribed by the eye surgeon to prevent complications. Several follow-up appointments will be necessary to confirm that the cornea is healing properly and vision is improving. If you have questions about using these eye drops, ask your pharmacist.
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