In most cases, both overcorrection and undercorrection of vision can be treated with an enhancement or retreatment procedure. However, those with very thin or steep corneas or a high degree of refractive errors may not be eligible for improvements. Overcorrection in a myopic LASIK case can be particularly challenging for both the doctor and the patient, as it requires a large amount of time in the doctor's office and optical rehabilitation, especially if the patient has presbyopia. The best way to avoid overcorrection is prevention.
A bad candidate for LASIK surgery is anyone who would not be fit to undergo normal LASIK or PRK surgery—such as someone with severe dry eyes, an abnormal topography, or unrealistic expectations. Tip-plugs are very effective in treating dry eyes that occur during waking hours, regardless of whether the situation is associated with LASIK or not. At the meeting of the American Society for Cataract and Refractive Surgery last year, Dr. Tal Rviv reported on the results of a series of 14 patients who had overcorrections in one eye after myopic bilateral LASIK, with an average spherical equivalent of + 1.00 D 1 week after surgery.
Refractive surgeons are often cautious to avoid overcorrecting a patient with excimer lasers, as this would involve blurred vision, removal of excess tissue and the need for a second surgery to treat the overcorrection. However, according to Gordon, patients have no more night vision or halos problems than a typical LASIK patient would have. If you feel absolutely good with clear vision, a little excessive correction isn't necessarily a cause for concern. It was concluded that the use of ocular and soft contact lenses appears to be safe and effective in reducing small amounts of hyperopia in myopic postoperative LASIK patients.
Gordon says that the procedure is quite simple and consists first of inducing an overcorrection of around 1.5 D, either in myopic or farsighted presbyopia, and then coming back and treating that overcorrection.