One of the more common side effects of LASIK eye surgery is undercorrection. This occurs when the excimer laser removes not enough of the excess tissue from your eye. Because of this, you may still have some of the refractive error left.

In order to correct undercorrection, a repeat refractive eye surgery, known as enhancement surgery, will have to be done. Enhancement surgery after LASIK should be done as soon as the patient's refractive error has stabilized. The stabilization of the refractive error typically occurs at around 3 months after the first operation. Most surgeons, however, would opt to wait longer before doing the repeat surgery. Usually, ophthalmologists wait until 6 months after the surgery. Up until the fist few years after surgery, the original corneal flap can still be lifted with relative ease. If you wait longer than a couple of years, the ophthalmologist may have to create a new flap of your cornea because the original flap would have healed completely by then.

After the original corrective eye surgery, the patient's eye will be examined and assessed by the ophthalmologist. The patient may have to undergo diagnostic examinations, such as corneal topography. Also, wavefront analysis may be done in order to accurately assess the patient's refraction. Doing these diagnostic examinations are needed in planning for the enhancement surgery.

Before the enhancement surgery is done, the patient first undergoes a slit lamp examination. The edge of the corneal flap is lifted up using a special instrument. After this, the flap is gently opened and held away from the eye with the use of surgical forceps. The rest of the procedure is similar to the original LASIK eye surgery. The excimer laser is then applied to the patient's eye. After the ablation is completed, the flap is again replaced in its original position. The flap may either be left to heal on its own or the ophthalmologist can use a contact bandage lens for the eye. The contact bandage lens helps in protecting the flap.

It is best if the ophthalmologist who did the original surgery also does the enhancement surgery. This is because the original ophthalmologist will know the details of the previous surgery, including the location of the flap hinge and the depth plate, which are helpful when trying to re-open the old corneal flap.

Before undergoing LASIK surgery, be sure to look for an ophthalmologist who offers free enhancement surgery, if needed.