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Risks and Complications of Laser Eye Surgery

Reviewed by Dr. Tony Pham

The following is a list of the most common risks and complications that may result from Laser Eye Surgery. Your surgeon should review all the possible complications before you sign the Informed Consent Form.

Complication Cause Symptom Correction
Over/Undercorrection Patients may be overcorrected to combat the eye’s natural reaction to regress. Undercorrection may be due to higher order aberrations Farsightedness or nearsightedness depending on whether the patient was under or overcorrected Overcorrection generally works out on its own. An enhancement might be needed in the case of an undercorrection
Loss of Best Vision Wrinkling of the flap Your best vision when corrected (using eyeglasses or contact lenses) is less than 20/20 Many times this can be corrected with another procedure where the flap is lifted and straightened.
Induced Astigmatism This can happen as a result of a poor ablation Blurred vision Can be corrected with an enhancement
Dry Eyes Normal for many after surgery A “sandy” feeling Usually goes away after 1-3 months. If not, the surgeon may suggest blocking your tearducts
Haze A cellular reaction during the ablation Vision doesn’t seem crisp Steroid drops, irrigation under the flap and even a pair of sunglasses can defeat most cases
Corneal Abrasion Happens during the forming of the flap when there is a cell breakdown. A feeling of something in the eye, blurring or tearing. Healing occurs naturally as the epithelium grows back
Glare and Halos Very normal post-op complication of LASIK Fuzziness around lights at night Usually goes away after 3-6 months. If not, glasses may be needed at night
Islands Small areas that didn’t receive enough laser energy ablation Ghosts or fuzzy images may appear An enhancement may be needed, but many times this goes away on its own
Flap Issues Poor surgical technique or patient’s accidently dislodging the flap Distorted vision Re-positioning the flap and smoothing it out
DLK This is a form of inflammation. Small white deposits under the flap Steroid drops
Infection Poor post-op care Discomfort and inflammation antibiotics


Because every patient is different, how they react to the amount of laser energy isn’t perfectly calculable. Often the procedure produces a slight over or under correction. This is generally temporary and will self-correct in 1-3 months time.

Of the two, undercorrection is more common. And it can be expected more often in patients with prescriptions further from the norm. Patients with higher order aberrations are more likely to have undercorrected vision. If the eyes have been undercorrected and it is noticeable an enhancement may be in order.

Many times the eye is over-corrected to combat the cornea’s natural reaction to regress to its original state. This will make a farsighted patient temporarily nearsighted and the inverse if the patient was nearsighted. Most times this stabilizes after 1-3 months. During this time glasses or contact lenses may be needed, and your surgeon may prescribe drops to improve your healing. If the overcorrection is substantial, an enhancement, generally 3-6 months after the original surgery, will be conducted.

Loss of Best Vision:

This means that the patient, even with their best correction (glasses/contact lenses) may lose the ability to read the 20/20 line on the eye chart. Usually, they can read the 20/30 or 20/40 line on the chart. This occurs many times when the corneal flap is wrinkled or when Diffuse Lamellar Keratitis (DLK) sets in. This, generally, occurs in less than 1% of all patients. Many times, these conditions can be reversed.

Induced Astigmatism:

This can result in blurred vision, but is managed in a retreatment with an over or under correction. If the procedure didn’t meet your expectations, it is likely due to an overcorrection, an undercorrection or an induced astigmatism. These can be corrected with an enhancement.

Dry Eyes:

It is very normal to experience a “sandy” feeling after LASIK Surgery. This typically goes away after 1-3 months. And during that time, it can be held in check with lubricating eye drops. If “dry eye” persists, despite the use of drops, your surgeon may suggest blocking your tear ducts so that your natural tears won’t wash away. This should result in improved lubrication.

If you have a history of “dry eye” prior to surgery, you should tell your surgeon, as this may affect the steps taken prior to the procedure.


Haze occurs when there’s a cellular reaction from the ablation. Serious haze occurs in less than 1% of patients that have PRK and is more rare in patients with LASIK. Moderate haze will not affect your vision and can be defeated by a pair of sunglasses in bright light.

Treatment with steroid drops and irrigating under the flap will usually resolve the haze issue. If the haze is causing a reduction in visual crispness then a mechanical debridement is necessary. This will remove the haze permanently.

Corneal Abrasion:

Occasionally, during the LASIK procedure, a small abrasion can occur. This happens during the forming of the flap, due to a breakdown of the cells on the epithelial surface.

The good news is that the epithelium grows back quickly, healing usually occurs in a few days.

Glare and Halos:

The experience of seeing glare and haloes is a rather common occurrence, not only for people having Laser Eye Surgery but people wearing glasses and contact lenses. That said, it can be worse for those having Laser Eye Surgery.

These problems generally decrease in severity by three months and most go away by six months. If they don’t go away, patients may need a weak prescription for night driving or to use eye drops reducing the size of their pupils. The general belief is that patients with larger pupils may have a higher risk of glare and halos.

With Custom LASIK using wavefront technology, some of the higher order aberrations, such as spherical aberrations are discovered before the procedure, reducing the possibility of glare and haloes.


These are areas on the cornea that didn’t receive enough laser energy during the ablation. This happened more often during the early years of Laser Eye Surgery, due to less efficient lasers. Even if it does happen, the symptom would be a ghost image or similar disturbance; generally it will go away on its own or can be made to go away with an enhancement.

Flap Risks:

Though it is rare, especially in the hands of experienced surgeons, flap risks do occur. The flaps may be too small, too short, too thin or irregular; even more rare would be a hingeless flap. Occasionally, the flap may shift due to rubbing or squeezing the eyelids.

If shifting happens, they may distort a person’s vision and require smoothing out. This is done by lifting the original flap and smoothing it into position. This has to be done quickly or can lead to a reduction in best-corrected vision.

Flap risks may be reduced with the use of All Laser Intralase or bladeless LASIK and there is nothing better than an experienced surgeon. Experienced LASIK surgeons have flap-related complications in less than one half of one percent of patients. And almost all can be fixed; though, in some instances, it may take a couple months before the patient is returned to their best-correct vision.

Diffuse Lamellar Keratitis (DLK)

DLK often referred to as “Sands of Sahara” and is an inflammation between the corneal flap and the stroma. The cause is unknown but what happens is the inflammation leaves small white deposits under the flap.

After the procedure, steroid drops are applied for one week to suppress inflammation. And a non-steroidial anti-inflammatory eye drop is administered after surgery. This can reduce discomfort after surgery. Most DLK cases will respond to steroid drops, but in severe cases the surgeon may have to lift the flap and irrigate the stroma to remove the cells. Treated properly, DLK rarely affects a patient’s visual outcome.

Infection or Severe Inflammation:

Infection is extremely rare and is avoided with proper surgical technique. But it is very important post-surgery for the patient to avoid contact with substances that may cause infection like eye makeup, hot tubs and swimming pools. It is also important to use antibiotic drops to prevent infection and to show up at all your appointments, even if everything seems to be fine.

Risks and complications can happen with every surgical procedure, and while this may seem like a long list, these complications are rare, especially in the hands of an experienced surgeon. Questions about risks and complications should be discussed with your surgeon.

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