Vision Correction Surgery

POTENTIAL COMPLICATIONS WITH LASIK

Just as all surgical procedures carry risks, so does the LASIK procedure. However, when LASIK is performed by an experienced surgeon, the risk of complications is quite low. In fact, this surgery is among the safest procedures today when performed properly.

Many complications are preventable, either by proper preoperative evaluation or expert surgical technique. An inexperienced surgeon may fail to detect a condition that would make you a poor candidate for LASIK, whereas an experienced surgeon may detect a contraindication and advise you not to have LASIK, or perhaps advise you to have a different procedure. There are many reasons to turn down a patient.

I’ve listed below both the rare and serious complications and the less rare and mild ones. Although this list is not exhaustive, it includes the possible complications that you need to know about in order to make an informed decision about proceeding with LASIK surgery.

UNDERCORRECTION

Undercorrection means that your refractive error wasn’t fully corrected by LASIK. If you were nearsighted before surgery, it means you are still a little bit nearsighted afterward. A slight undercorrection will not seriously affect your vision and may even be desirable in nearsighted patients over forty to help with their reading vision. If the undercorrection is enough to cause significant blurring of vision, we recommend an enhancement procedure for you.

OVERCORRECTION

Overcorrection means that your refractive error was corrected more than intended. If you were initially nearsighted, overcorrection means that you are farsighted after LASIK, making it hard to see clearly up close. If you were farsighted before LASIK, an overcorrection would make you nearsighted. In this case, your distance vision would be somewhat blurred and your near vision rather good.

An initial, temporary overcorrection is not uncommon, and usually rights itself in the first month as the eye heals. Patients can manage a temporary overcorrection by wearing glasses until the problem resolves. As with undercorrections, a significant overcorrection can be treated with an enhancement procedure, after your vision has stabilized.

DRY EYE

LASIK makes the eyes somewhat drier than before surgery, usually for the first few months. For most patients this is not a problem because the eyes have more moisture than needed, so a little dryness is not bothersome. However, in rare cases patients develop more significant dryness after LASIK. These patients experience dryness throughout the day. You are more at risk for this condition if you have dry eyes before LASIK while wearing glasses. (Many people have dry eyes while wearing contact lenses, but these people are usually excellent candidates for LASIK because the eyes can be much more comfortable after LASIK than with contacts.) An important part of the comprehensive examination is an evaluation of your tears to ensure that your chance of experiencing post- LASIK dryness is minimal.

If you develop significant dryness, a variety of treatments are now available. These include taking dietary supplements, using lubricating eyedrops, using an eyedrop called cyclosporine that improves tear production, and blocking your tear drainage canals with tiny plugs to retain more tears in your eyes.

CORNEAL ABRASION

The eye is covered by a thin layer of skin, called the epithelium. This skin is just like the skin on your hand except that it is clear so you can see through it. Occasionally, the minor trauma of surgery causes part of the epithelium to fall off. This is called a corneal abrasion or corneal epithelial defect, and occurs in about 2 percent of LASIK patients. This doesn’t harm your eye and doesn’t interfere with the laser treatment. Your eye will feel scratchy for a few days while the epithelium heals. Abrasions always heal, usually in one to three days.

NIGHT STARBURST AND HALOS

All people, whether or not they have had LASIK, experience some starburst or halos at night. These night-vision disturbances occur when you are in a dark environment and look at a small bright light, such as a headlight or a streetlight. Halo is the glow that surrounds the light source, and starburst is little spiky rays of light that emanate from the light source. Starburst and halos occur because the pupil dilates in low-light conditions. The dilated pupil allows more peripheral light rays (rays coming in from the sides) to enter the eye. These rays are more likely to scatter, instead of coming to a precise focus. You perceive the scattered light as starburst or halos. Look carefully at a headlight or streetlight tonight so you understand what I’m talking about. Incidentally, this scattering of light is why everyone notices that their night vision is not as good as their daytime vision.

Some patients experience an increase in starburst and halo after LASIK. These symptoms can be bothersome in dimlight conditions, such as driving at night. Starburst and halo improve gradually, and the overwhelming majority of significant starburst problems disappear on their own by six months. However, if you still have significant starburst or halos at six months, they tend to persist.

No one can predict whether you will get more starburst or halos after surgery, but we can tell you your odds. If you have high myopia or high astigmatism, you have more chance of noticing significant night-vision disturbances. In one FDA study in which I was a principal investigator, about 10 percent of highly nearsighted people noticed halos all the time at night. This is a primary reason that I prefer the implantable contact lens for high levels of myopia. If you have a low or moderate correction, then significant night-vision disturbances are rare. Many eye doctors used to believe that patients with larger pupils had a greater chance of developing starburst or halos at night, but a number of major studies have now shown that this is not true.

If you develop significant starburst or halos after LASIK, there are treatment options. A light prescription for night driving can help, as can the use at dusk of eyedrops that reduce the size of your pupils. The newer wavefront-guided laser treatment has been shown to significantly reduce night-vision disturbances compared with conventional laser treatment, which is another reason I use wavefront-guided treatment in all eligible patients.

PROBLEMS WITH QUALITY OF VISION

Rarely, patients after LASIK experience a slight decrease in quality of vision. Vision can seem slightly dirty or hazy, like wearing glasses or contacts that aren’t clean. Vision tends to improve over time. This complication is very rare except in those with very high levels of nearsightness or astigmatism. This is another reason I prefer implantable contacts lenses for extreme myopia.

CORNEAL FLAP COMPLICATIONS

The nonlaser microkeratome can occasionally cut the flap incorrectly. The flap can be left too small, too thin, detached, or have a hole in the middle. If this happens the surgeon will abort the operation and replace the flap. This complication is extremely rare with all-laser LASIK, which is another reason I prefer all-laser LASIK over the microkeratome blade.

STRIAE

Rarely, the corneal flap may shift slightly in the first twelve hours after LASIK surgery. If the flap shifts slightly, wrinkles form, just as wrinkles form in a carpet if you step on it and it isn’t properly nailed down. The medical term for these wrinkles is striae. If striae are present in the center of the cornea, they may blur your vision. You will be asked to keep your eyes closed and not to rub your eyes for the first few hours after surgery, which helps prevent the flap from shifting.

Fortunately, striae are easy to fix with a short procedure. The flap is lifted and laid back down smoothly. The surgeon places a bandage contact lens to hold the flap securely in place overnight.

EPITHELIAL INGROWTH

The cornea is covered by a thin, clear skin, called epithelium. This clear skin is made of epithelial cells. When the LASIK flap is lifted and replaced, these cells normally grow back over the top of the flap. Rarely, the cells grow under the flap instead. This condition is called epithelial ingrowth. These cells can cause blurred vision or irritation. Epithelial ingrowth is easy to treat if detected early by gently lifting the flap and clearing away the trapped epithelial cells. Detecting epithelial ingrowth is one of the reasons why it is important that you return for your scheduled follow-up visits.

CORNEAL ECTASIA

I have already noted that keratoconus makes you a poor candidate for LASIK. Corneal ectasia is what we call keratoconus that develops after LASIK. It is very rare. Some patients develop ectasia because the surgeon was too aggressive in removing tissue during the procedure. Some patients with ectasia after LASIK had keratoconus that should have been detected preoperatively but wasn’t. This is one of the reasons a careful preoperative exam is so important.

Rarely, some people develop ectasia after a LASIK procedure that was done properly after there was no evidence of keratoconus in the preoperative exam. It appears that these rare individuals had subclinical keratoconus before surgery. Subclinical means it was present but not detectable. In some of these individuals, the LASIK flap seems to accelerate the underlying disease. In others, it appears they would have developed keratoconus even without LASIK surgery because of their genetic predisposition.

Corneal ectasia is rare in anyone, but less rare in young people with high corrections and thin corneas. In those patients at risk of ectasia, we may recommend PRK or the implantable contact lens instead.

Ectasia and keratoconus can now be arrested with a procedure called corneal crosslinking. In corneal crosslinking, the cornea is saturated with riboflavin, a vitamin, which is then exposed to ultraviolet (UV) light. The UV light causes the riboflavin to bind to the corneal tissue, strengthening the cornea and stopping the progression of the disease.

INFECTION AND OTHER POTENTIAL SERIOUS COMPLICATIONS

Infection is extremely rare after LASIK, occurring in about 1 in 10,000 surgeries done by an experienced surgeon. It is a feared complication because an infection can cause a scar in the cornea, causing blurred vision. The good news is that infection is much rarer with LASIK than with the use of contact lenses, so from the point of view of serious complications, LASIK is safer than contact lenses.

As with any surgery, proper technique is the best way to avoid infection. If your eye does become infected, it will likely occur during the first forty-eight to seventy-two hours after LASIK. This is why it is so important for the first week to avoid any contact with substances that carry bacteria, such as old eye makeup, hot tubs, and swimming pools. It is also essential to go to all of your follow-up visits, even if everything seems fine. You may be prescribed antibiotic eyedrops after surgery to prevent infection.

Any surgery can result in loss of vision. Fortunately, this is extremely rare with LASIK. We have never had a patient lose their vision from LASIK. An important publication from the Oregon Health and Science University compared the risk of loss of vision from LASIK to the risk of loss of vision from contact lenses, and found that LASIK was the safer option. Nevertheless, you shouldn’t be complacent. It is important to follow all the surgeon’s instructions, both pre- and postoperatively, to make the LASIK procedure as safe as possible.

History Of Vision Correction History