Intraoperative Complications of LASIK are those complications which occur during the treatment process itself. They may lead to the treatment being cancelled, postponed, or completed with a reduced chance of the patient getting a good result. It is important for patients to know what can go wrong during the LASIK procedure.
Intraoperative Complications during LASIK generally originate at two points-during the flap making process, and during the laser reshaping process. There are other, more general complications. For example, the patient could get a reaction to the anaesthetic drops. But these have such a small chance of occurrence, that these may be safely ignored. After all, you don’t stop crossing the road simply because there is the possibility that you may get hit by a passing car!!
Complications during the flap making process: The majority of the complications during LASIK can occur due to the flap making process. It is estimated that the likelihood of complications with the newest generations of mechanical microkeratomes is about 1%. It is certainly less than this when a Femtosecond laser microkeratome is used. But more about that later.
With mechanical microkeratomes used to make flaps, the following complications can occur:
Incomplete flap: The flap that is created does not open enough to allow the laser treatment to be carried out. This can happen because the patient suddenly squeezing the eye, stopping the microkeratome treatment. It can also happen because microkeratome suction is lost suddenly, terminating the procedure. Or it can happen that the doctor simply lifted his foot off the footswitch!! The normal procedure that is followed is that the flap is replaced back in place, and the treatment postponed. After a few weeks, the treatment procedure can be repeated.
Free Cap: The idea in LASIK is to make a hinged flap. The hinge provides an anchor to the flap, and helps retain it on the eye. Sometimes, the hinge can be too small (especially if the flap is too large), and break off. At other times, a free cap is created when the suction is lost during the procedure. If the free cap exposes the cornea in an area large enough for the laser reshaping process to be carried out, the procedure is generally completed in the same session. The free cap is placed back on the eye. Patients must take extreme care not to rub the eye, or make violent movements with the eye during the first couple of days after the procedure, because there is a risk of losing the flap completely, which is clearly not pleasant, though not altogether disastrous!!
There are other flap making complications-there could be an irregular flap, or a very thin flap or a buttonholed flap (i.e., a donut shaped flap). These are quite rare with modern microkeratomes. Generally the treatment in all these cases is suspended, and then repeated after a few weeks.
There can also be laser complications.
The laser energy may not be perfect: This can happen because of poor control over environmental conditions in the laser room. It can also be because of some organic vapors like alcohol or perfume. Both the patients and the doctor must refrain from carrying strong smells into the room. If the laser energy is not perfect, then there may be an under correction or an over correction.
The treatment zone is not homogenous: If the laser is malfunctioning, or the corneal hydration is not uniform in all areas, the treatment zone can be irregularly treated. This can lead to severe visual symptoms for the patients. This can only be corrected with a topographically linked laser enhancement.
The treatment zone is not centered: If the treatment zone is not centered on the pupil, the patient can experience severe visual symptoms. This can happen, even if rarely, even with lasers with sophisticated eye trackers.
The flap hinge gets laser radiation: If the flap area is small, there is a chance that the flap hinge will get laser spots. This again leads to severe visual symptoms for the patients.
The nice part about LASIK is that generally, all the complications are not vision threatening. They merely lead to the treatment being postponed, or they heal relatively well over time. Remember, as a patient, don’t create an atmosphere that the doctor would feel defensive about postponing the procedure. If the procedure is postponed, it can always be repeated. However, in the case of a buttonhole, or irregular flap or a small flap, if the treatment is carried out, it can lead to severe visual symptoms, which may not be easy to treat.