Laser-in-situ-keratomileusis or LASIK surgery cuts a flap into the surface of the cornea and removes some of the underlying corneal bed tissue, which adjusts the shape of the lens. The corneal flap is dropped back into place and the newly reshaped lens typically improves vision. Various corneal flap defects can be introduced such as cutting incomplete flaps, cutting flaps too thin, cutting off the flap hinge and creating flap wrinkles or folds called flap striae. These corneal flap defects can induce various vision complications.
Permanent Vision Loss
Some patients report a permanent reduction of vision post-Lasik that cannot be corrected by contact lenses, glasses or further surgery according to the Food and Drug Administration, which regulates medical devices including the lasers used for Lasik. If the cornea becomes permanently scarred or the corneal shape becomes highly irregular after Lasik surgery, it may be impossible to wear contact lenses.
Night Vision Problems
Performing well on an eye chart is not the only measure of good vision. Some patients see an improvement in their eyesight as measured by the eye chart, but have inferior night vision. Almost 47 percent of patients reported problems with night vision according to Dr. Delphine Saragoussi in the article, Lasik, PRK and quality of vision: a study of prognostic factors and a satisfaction survey, published in the September 2004 issue in the "Journal of French Opthamology." The most common night vision complaint was seeing halos around bright objects. Excessive glare and double vision under night time conditions has also been reported.
Under or Over Corrected Vision
Between 5 to 51 percent of patients report under correction and between 3 to 7 percent report over correction after Lasik surgery, based on a review of clinical studies. Patients with more severe myopia pre-operatively tend to experience more regression to their pre-operative vision. Many post-Lasik patients find they still need some correction with contact lenses or glasses to achieve 20/20 vision. Patients who needed reading glassed before surgery will likely need reading glasses after surgery unless they request monovision, in which one eye is corrected for reading and one eye corrected for distance vision.
Severe Dry Eye
Because of nerve damage when the Lasik flap is created, some patients experience problems with tear production after Lasik surgery. Patients may have permanently dry eyes, requiring frequent use of lubricating eye dops for comfort. Dry eyes can result from cutting nerves that regulate eye-blinking and production of secretion from the meibomian gland that prevents evaporation of the tear film covering the eye according to Dr. Ikuko Toda in his review article, Lasik and Dry Eye, in the March/April 2007 issue of "Comprehensive Opthamology Update."
References
- FDA: What are the risks and how do I find the right doctor for me?
- "Indian Journal of Opthamology": Complications of laser-in-situ-keratomileusis, Mittanamalli S Sridhar et al. , 2002
- "Journal of French Opthamology":Lasik, PRK and quality of vision: a study of prognostic factors and a satisfaction survey, Saragoussi D and Saragoussi JJ, Sept. 2004
- "Comprehensive Opthamology Update": Lasik and Dry Eye, Ikuko Toda, March&April 2007
- NIH Medline Plus :Lasik Eye Surgery
