Post-operative complications are complications associated with healing that occur after the patient leaves the laser room.

Studies show that approximately 6% of LASIK patients suffer from some complications of surgery which were manifest only some days after the surgery. It should be noted, however, that such studies are somewhat dated, and with the latest knowledge and technology, this percentage is probably less. Some of the complications include:

a)      Dry Eye Disease

b)      Interface Debris

c)      Corneal Edema

d)     Micro Straie or wrinkles in the flap

e)      Flap Displacements

f)       Persistent Corneal Epithelial Defect

g)      Interface Epithelial Ingrowth

h)      Persistent Discomfort or Pain in the eye

i)        Progressive Corneal Thinning

j)        Overcorrection, Undercorrection and Regression of the treatment

k)      Diffuse Lamellar Keratitis

l)        Infection

It should also be noted that not all the above complications have the same effect on a patient’s vision or vision quality. Some, like interface debris, which is the most common, rarely causes any difficulty to a patient. Others, like progressive thinning or Diffuse Lamellar Keratitis, though rare, can have quite severe consequences for vision.

Overcorrection, Undercorrection and Regression

Every eye heals differently.  Patients who are either aggressive or slow healers may experience an under correction, or an overcorrection.

In addition, the cornea may experience some slight remodeling and new cells may grow after LASIK. This might result in a slight loss of refractive  effect  post-operatively. This is called regression. In general, the higher the correction undertaken, the more likely regression is to occur, and this is especially true for treatment of hyperopia greater than +5D and myopia more than -10D.

In most cases, undercorrection (where the treatment did not cause the desired level of change of vision and correction of the refractive error) and regression can be treated with an enhancement procedure. Overcorrection can also be corrected with an enhancement procedure. It may not always be safe or appropriate for patients to undergo enhancement procedures. This could be because the cornea is too thin post the first procedure, or has ended in a situation where it is too steep (for correction of plus errors) or too flat (for correction of minus error) which makes it prone to remodel. Before undergoing an enhancement, you should discuss its safety with your eye surgeon.

Diffuse Lamellar Keratitis (DLK)

Diffuse lamellar keratitis is an inflammatory reaction to the LASIK procedure in your eye. Mild cases of DLK occur in about 1% of the cases, while severe cases are relatively rare. Why DLK occurs is not very well understood, and a number of conditions within the eye, the operation theatre, the instruments used for LASIK, and the surgical technique have been implicated as the causes of the complication. It is imperative that DLK is treated as early as possible, perhaps with an increase in the anti-inflammatory drops after LASIK, and perhaps by lifting the flap and washing of the flap interface.

DLK is easy to treat when caught early. Usually, a patient does not realize that he/she has DLK till it reaches a relatively advanced state. However, eye surgeons should be able to pick it up. DLK usually occures within 24-72 hours after LASIK, but sometimes it can happen even several months after LASIK. Please do keep your follow-up schedule with your eye doctor, and also alert your eye doctor, if you notice a marked deterioration of your vision after the procedure.

Flap Folds, Wrinkles & Striae

Usually minor flap striae, or fine wrinkles in the flap after LASIK surgery, do not interfere with patient vision. In such cases of visually insignificant flap striae, the eye is just left alone. Sometimes the striae are serious enough to decrease vision and cause discomfort to the patient. In such instances, something needs to be done by the eye doctor.

To remove the striae, an eye doctor may simply place a zero power contact lens in your eye for a few days. Or a surgeon might lift the flap, stretch it, irrigate beneath it and lay it back down in the proper position. This is a skilled procedure, and high volume surgeons are usually the only ones who have experience with it.

Why do straie occur? Usually, when the flap drapes back on the reshaped cornea, it may not drape back perfectly. It could also happen because the eye gets rubbed during the first few hours after LASIK.

Epithelial Ingrowth

Epithelial ingrowth is a condition in which epithelial cells, which normally cover the surface of the cornea, grow beneath the flap.

Most epithelial ingrowth does not affect vision and does not require treatment. In such cases, many doctors will simply leave the ingrowth alone and monitor it at post-operative visits. However, in about 1-2% of cases, epithelial ingrowth occurs within the field of vision or affects an area wide enough to require surgical treatment or removal. Central visually significant epithelial ingrowth can appear as early as 1-2 days post-operatively. However, epithelial cells most often appear at 1-3 months post-operatively. Therefore, it is important that patients attend all follow-up visits with their doctors, especially for the first 6 months post-operatively.

Sometimes, doctors will prescribe eye drops to minimize the effects, and this protocol will be sufficient. However, at other times a more aggressive approach will be necessary. Removing the epithelial cells is a relatively simple procedure. The ophthalmologist would lift the flap, wipe the underside of the flap with a swab-like sponge, then lay the flap back down. In rare cases where the epithelial ingrowth persists despite such removals, the surgeon may need to use sutures to secure the flap down and ensure that ingrowth cannot occur.