LASIK Surgical Risks

All surgical procedures, including ASA or LASIK eye surgery, involve risks of unsuccessful results, complications, infection, serious injury, or even death, from known and unforeseen causes. Neither your LASIK surgeon, nor your optometrist, nor the office staff, can promise or guarantee that laser eye surgery will be effective or make your vision better than it was before laser eye surgery.

It is possible that laser eye surgery or a complication arising from laser eye surgery could make your vision worse or could injure your cornea or your retina. This may result in partial or total blindness, or could require a cornea transplant. Certain inflammatory conditions can cause severe post-operative complications such as corneal or flap inflammation or thinning, which could result in permanent loss of vision. In addition, because the laser eye surgery is fairly new very little is known about the long-term effects of the procedure. During your preoperative examination, the likely outcomes (e.g. uncorrected vision) will be conveyed to you based on the level of your particular refractive error. Although it is not possible to list every potential risk or complication that may result from the laser eye surgery, many of them are described below.

Halos or Starbursts

Some patients may not see as clearly at night or in dim light. They may notice an optical effect called halos or starbursts around lights and illuminated objects after laser eye surgery. Patients who notice these effects may need to wear eye glasses to drive at night. These effects are for the most part temporary, but could be permanent and uncorrectable. These optical side effects may be more likely to occur in patients with larger-than-average pupil size or higher corrections.

Laser Equipment Malfunction

The microkeratome and excimer laser are maintained according to strict manufacturer specifications. Despite this maintenance, the microkeratome or the excimer laser could malfunction, requiring laser eye surgery to be stopped before completion. In some instances, this could result in a loss of vision, or rescheduling of the procedure.

Under-correction or Over-correction of Eye

The precise reshaping of the cornea performed by the laser may be overridden in some cases by the healing response of the eye. While the treatment of your refractive error is designed to completely neutralize your refractive error (unless otherwise discussed with your LASIK surgeon) this treatment is aimed at the "average" eye. If your eye heals in a different way from the "average," an over- or under-correction of the refractive error may result. A patient's tolerance for under-correction or over-correction varies. In the majority of instances, the over- or under-correction can be corrected with eye glasses, contact lenses or additional laser eye surgery. In other instances, it can be permanent and not amenable to surgery because of structural stability issues or the presence of an irregular corneal surface.

Increased Light Sensitivity or Fluctuating Vision

Patients may be extremely sensitive to light and glare or find that their vision fluctuates after LASIK eye surgery. These conditions are generally temporary and usually go away within one to three months after the procedure. However, in some cases they could be permanent.

Optical Imbalance in Eyes

If the surgeon performs laser eye surgery on each eye on different days, the eyes may not be able to balance and focus properly until the procedure is performed on the other eye because there will be a power difference between the two eyes.

Infection, Hemorrhage, Blockage, Drug Reactions

Other LASIK risks include severe infection that cannot be controlled by antibiotics, hemorrhage, corneal swelling, retinal detachment, venous or arterial blockage, cataracts, drug reaction, or other complications. These complications range from minor, temporary problems to major, permanent conditions, including but not limited to perforation of the cornea, retinal damage, loss of an eye. These complications could cause partial or total blindness.

Vision Regression

The cornea is living tissue. Once tissue has been removed from the cornea during the laser eye surgery, the epithelium (surface layer of cells) may thicken to compensate for the change in shape that has occurred. This happens to a variable degree among treated patients, accounting for the reason why some patients have a stable result (minimal epithelial thickening) and others regress (more significant epithelial thickening). Vision regression is more likely to occur in very nearsighted (myopic) patients. In some cases, the patient can have additional laser eye surgery to further improve distance vision. In other cases where tissue availability for safe laser retreatment is limited, the regression is corrected with eye glasses or contacts.

Increased Pressure in the Eye

The steroid drugs used during the first week after laser eye surgery may, on rare occasions, cause increased pressure in the eye. This raised pressure needs to be closely monitored and may require additional topical or oral medications if significantly elevated. It is important for you to return for scheduled follow-up visits to monitor your eye pressure in order to modify the medication schedule as needed.

Eye Fragility on Impact

For at least three months after laser eye surgery, the eye should be considered fragile to direct trauma. When participating in sports or other activities involving possible contact with the eye during this period, you should wear protective eyewear. In any event, it is advisable to protect your eyes from direct trauma after LASIK surgery as much as possible.

Eyelid Droop

The eyelids have a natural tendency to droop with age. The eyelid speculum or medications that are used during laser eye surgery may hasten this process.

Corneal Ectasia

A certain amount of corneal tissue must remain under the flap after the laser has achieved tissue removal. This is believed to relate to the long-term stability of the cornea. In rare instances, imprecision in the accuracy of the keratome cut, coupled with inaccuracy of the pre-operative corneal thickness evaluation can result in less tissue being left under the flap than intended. This can have two effects: it can either result in bulging of the cornea thus reversing the intended flattening effect of the treatment, or it can lead to progressive deformity of the cornea with thinning and increasing curvature changes, and an irregular shape. In more severe instances, the condition of progressive deformation is called ectasia and may require a corneal transplant in order to restore vision. The probability of this occurring with currently employed modern technology is thought to be approximately one in 10,000.

Inadequate Flap

The corneal flap may be too thin, too thick, uneven, and too short, may wrinkle, become displaced or may not heal properly. This condition could be temporary, requiring that LASIK eye surgery be postponed until the surgeon can create a new flap, or could cause permanent damage to the cornea. In addition, there is a risk that the "hinge" of the flap may be cut off from the cornea (also known as a "free flap"). In some instances, the LASIK surgeon can still perform laser eye correction, reposition the detached flap on the cornea, and place a contact lens on the eye to promote healing, but in some instances he may choose to wait to perform laser treatment until after the flap heals. If, however, a "free flap" is lost, the patient could experience permanent corneal damage. If the damage or distortion in vision is severe, a corneal transplant may be necessary to restore vision.

Debris or Infection under the Flap

Sometimes after the surgeon creates the flap during LASIK eye surgery, there may be a small amount of debris or tissue under the flap. Debris can result from the instruments used or consist of tear-film oil or floating material. The LASIK surgeon may decide in the immediate post-operative period to irrigate beneath the flap to remove this debris. Small amounts of debris can generally be monitored in the clinic without surgical intervention. In most cases, debris that is left behind is cleared in time by the body's own clearing systems. Infection, on the surface of, or beneath the flap is a rare event, estimated to occur at a rate of one in 10,000. Infection is managed by starting antibiotic eye drops and in some instances, taking cultures of the cornea. Your LASIK surgeon might even need to lift the corneal flap to culture and treat the infection. If the infection results in significant scarring of the cornea, a partial or complete corneal transplant may be necessary to restore vision.

Diffuse Lamellar Keratitis or "Sands of the Sahara"

In some cases, patients experience a temporary complication caused by an inflammatory reaction between the flap and the corneal bed of the eye. This condition has been called "Sands of the Sahara" or Diffuse Lamellar Keratitis (also known as "DLK"). The exact cause of this complication has not been determined. Patients with DLK may not show any symptoms at all or may experience blurred vision and tearing, which can last from several days, up to several weeks, and may delay the healing process. DLK can generally be treated with topical or oral steroids, or surgical intervention.

Epithelial Erosion

The epithelium is the surface layer of cells over the stromal layer of the cornea. If the epithelium is cut or removed, it generally grows back. During LASIK eye surgery, the surgeon creates a flap consisting of the epithelium and stroma and holds the flap back while performing the laser procedure. The epithelium in some people is less well attached to the underlying stroma; such eyes are at increased risk for epithelial scratches or epithelial sliding, especially as the flap-maker is passing over the corneal surface to create the flap. In some cases, we can identify eyes at risk and advise about the increased risks associated with laser eye surgery. There are, however, rare patients where there are no pre-operative clues. In addition, older patients are more likely to have areas of loose epithelium during flap creation. In such instances, the surgeon places a contact lens over the cornea at the end of the LASIK eye surgery to assist in healing and to reduce discomfort. Patients who experience an epithelial slide or abrasion may experience a longer recovery period and may be a risk for complications including infection, inflammation, recurrent erosions, flap wrinkles or epithelial ingrowth. The surgeon may postpone and reschedule LASIK eye surgery until the eye heals, he may choose not to treat the second eye at the same session following a severe slide or erosion on the first eye, or he may advise ASA for the second eye.

Epithelial Ingrowth

Epithelial ingrowth is a condition in which epithelial cells from the surface of the cornea grow under the edge of the flap. If the cells continue to grow, they can affect the underlying tissue causing astigmatism, flap edge thinning and reduction of vision. This condition is generally treated by medication and observation, although further surgery to remove the epithelial cells from the interface may be necessary.

Dry Eyes

Dry eyes are a common, but generally temporary, complication arising from ASA or LASIK eye surgery. This condition can usually be treated with lubricating eye drops and occasionally with temporary inserts or "plugs" that prevent the normal drainage of tears into the nose. Dry eye generally improves within six to nine months after laser eye surgery, but in some instances can continue for longer periods of time, and may require long-term use of lubricant drops and permanent plugs. Patients who have dry eyes prior to ASA or LASIK eye surgery are likely to experience dry eyes after surgery.

Vascular Occlusion

When the suction ring is applied to the eye during the flap-making process, the pressure in the eye increases significantly. Most patients will notice that the light will dim or go out completely in the eye. When the suction ring is removed, the vision is restored to the eye within a few seconds. There is a remote risk that when the suction ring interrupts the blood supply to the eye, permanent damage to the retina (the film of the eye camera) and loss of vision can result. This possible occurrence has a theoretical probability of less than one in 1,000,000.

Microscopic Corneal Haze

Microscopic irregularities on the surface of the cornea can cause slight vision loss. One to two percent (1-2%) of patients may lose up to two lines of vision on the eye chart after laser eye surgery.

Excessive Corneal Haze

Although corneal haze is part of the normal healing process, and gradually subsides with little or no permanent effect on vision, if the haze is excessive or does not go away, the patient may have some permanent blurring of their vision. Sometimes additional laser eye surgery may help.

Elevated Intraocular Pressure (IOP)

Because a steroid drop is used post-operatively to control the healing response, some patients may experience a rise in their intraocular pressure (IOP). You will need to be monitored and may require an additional medication to control the pressure until you have completed your prescribed steroid medication.