Problems with Quality of Vision
A small number of patients experience a slight loss of quality of vision after LASIK surgery. This is also called loss of best-corrected vision. Loss of best-corrected vision means that, even with eyeglasses, a patient loses some of the visual crispness and clarity he had when wearing eyeglasses prior to surgery. The person may no longer be able to read the 20/20 line of the Snellen eye chart. He may also notice some hazy vision or ghost images. Loss of best-corrected vision can be a result of irregular healing or an irregular flap and may improve over the first year. This complication is very rare except in those with very high levels of nearsightness or astigmatism. Careful surgical technique and good follow-up care help minimize the incidence of this problem.
Development of a “Central Island”
Another potential complication from LASIK is the development of a central island, a small raised area in the cornea’s treatment zone. Central islands often disappear spontaneously after several months, but some require an enhancement procedure; in this, the corneal flap is lifted and a small amount of excimer laser energy is delivered to the raised area. When the central island is removed by additional laser treatment, crisp vision usually returns.
Dr. Kornmehl diagnoses a central island by using a corneal topographer, the device that produces a digitized contour map of the corneal surface. To help prevent central islands, some excimer lasers have special software that distributes additional pulses centrally, along with the regular treatment for the refractive error. With the latest generation of excimer lasers, the incidence of central islands is very low.
Corneal Flap Complications
For experienced surgeons, corneal flap complications are rare, occurring in about 1 in 2,000 procedures. This complication is characterized by a flap that is too small, too thin, detached, or irregularly shaped. After Dr. Kornmehl makes the flap, he inspects it. If there are problems with the flap, Dr. Kornmehl may not proceed with the laser treatment. He will replace the flap and terminate the operation. While this complication is frightening, it almost never harms vision if handled properly. The LASIK procedure can usually be successfully repeated in 6 months, after the eyes heal.