Both PRK and LASIK procedures involve a few risks. The chances of having severe vision-threatening side effects of laser eye surgery are very low. However, there have been a few cases of serious eye injury which required corneal transplant.

Infection and delayed healing

Approximately 0.1 percent of all patients suffer from corneal infection after PRK and slightly fewer after LASIK. This usually means an additional discomfort and slower healing, but no long-term effects after a period of four years.

Under correction/Overcorrection

Under correction or overcorrection is also one of the most common side effects of laser eye surgery. A surgeon cannot predict precisely how your eyes will respond to treatment. This means you might need to keep wearing corrective lenses after surgery. In some situations, you can have another surgical procedure to improve the results.

Decrease in Best-Corrected Vision

After a laser eye surgery, a few patients find that their best-corrected vision with contact lenses is worse than before. This is also one of the side effects of laser eye surgery, usually resulting from irregular tissue removal.

Excessive Corneal Haze

Corneal haze is part of the normal recovering process after a PRK procedure. It usually has no significant effect on the final vision and can be noticed only by an ophthalmologist with a microscope. However, in some cases, excessive haze can interfere with vision. The risk for having this side effect is much lower with LASIK than PRK.

Regression

This is yet another possible side effect of laser eye surgery. For some patients, the eye returns to its initial state within a few month. A new surgical procedure is usually possible in such cases.

Halo Effect

The halo effect can affect both PRK and LASIK patients and is noticed in low light. As the pupil becomes larger, a second faded image forms due to the untreated part of the cornea. This can often interfere with night driving.

Flap Damage or Loss

This side effect of laser eye surgery can only affect patients undergoing a LASIK procedure. In some cases, instead of creating a hinged flap on the center of the cornea, the entire flap tissue comes off. This can usually be replaced after the laser treatment. However, in some cases, the flap can be damaged or lost.

Distorted Flap

This side effect of laser eye surgery also affects only patients who have had a LASIK procedure. It consists of a distortion in the shape of the cornea created during the healing process, which can result in a lower best-corrected vision.

Other Side Effects of Laser Eye Surgery

Even when both the procedure and the healing process seem to go perfectly, there are some side effects that may still cause dissatisfaction. Older patients, for example, cannot have both good distance and near vision in the same eye without wearing glasses or contact lenses. Patients suffering from myopia which could still read without glasses may no longer be able to do that after surgery. If both eyes are not treated in the same time, the eyes might work awkward together in the period within the two treatments.