Not all patients get a satisfactory result from excimer laser eye surgery. This may be due to undercorrection, overcorrection, or one of several other complications. By far the most common problem is an undercorrection or overcorrection.
Patients who experience undercorrection or overcorrection can usually undergo a second procedure, known as an enhancement, to obtain a better correction. In most cases, a significant improvement in the vision will occur, but it is important to realize that this, too, is a laser procedure and therefore has the same laser eye surgery risks of the first procedure. It is possible but rare that your vision can be worse after an enhancement procedure. Complications can occur, even if no complications occurred during your first procedure.
If your vision is quite good after your excimer laser eye treatment, but not perfect, you should consider carefully whether you want to have an enhancement procedure. Maybe you can easily adapt by wearing glasses on a limited basis, such as for driving or watching movies. If your vision is really not satisfactory, then an enhancement procedure is a good idea.
Overall, around 10 to 20 percent of patients undergo enhancement procedures, though your likelihood will vary significantly depending on your degree of nearsightedness, farsightedness, and astigmatism. Over 25 percent of patients with extremely high degrees of nearsightedness, farsightedness, and astigmatism are likely to require enhancement procedures.
From a study it was found that one patient ended up slightly undercorrected in both eyes after having PRK, which meant she was still somewhat nearsighted. She had excellent vision for close-up work, but distances were a problem – especially when driving at night. She got prescription glasses as a “security blanket,” she said, “because it’s a little scary to wait until you get right up to the street signs to read them”. But she decided soon after to have an enhancement procedure on her right eye.
The enhancement, she said, “was a snap, because I knew what was going to happen. It was like seeing a movie the second time.” The procedure was identical to the first surgery, except it took even less time to complete. She took a pain pill for less than twenty-four hours and never experienced any pain, swelling, or light sensitivity. “Having one eye done was a breeze, because I could rely on the other eye. It was like it didn’t happen,” she said. Within three days, she was driving without glasses, wearing makeup, and was back at work.
Another patient decided to have touch-up surgery four months after he first had LASIK. He was. 20/40 in one eye and 20/70 in the other, and was straining to see distances when driving.
The touch-up LASIK procedure differed slightly from the first operation. Rather than using the keratome machine to cut a thin flap in the cornea, the doctor was able to see the outline of the original flap and reopen it by hand. The procedure itself was painless, but the patient reported experiencing slightly more postoperative discomfort after the second surgery than he had felt after the first. The corneal flap irritated his eyelid. “It felt like something was in my eye, and I wanted to rub it,” he says. The doctor put in a protective contact lens, and the pain disappeared.
The next day, he could read license plates. His vision had improved to 20/25, and he wasn’t feeling any discomfort. Today, he doesn’t need glasses for reading or distance.
