Patient Management
Preventing Longer-Term Effects of LASIK
The risk of long-term complications is small. Proper prevention and management make it even smaller.
By Sandra Belmont, M.D., New York, N.Y.

During the past 10 years I've performed LASIK on several thousand patients. Most of them have described the procedure as "a miracle." It's clearly the beginning of a wonderful and emotionally rewarding change of lifestyle for these individuals. However, approximately 1% of LASIK patients do experience mild to severe complications postoperatively. So, although the benefits of this surgery far outweigh the risks, an occasional complication must be expected.

Given that some risk is inevitable, we must do everything we can to minimize it and ensure the best possible outcomes. Here, I'd like to share some of my experience preventing LASIK-related complications and managing the complications on those rare occasions when they do occur.

Undercorrection/overcorrection/regression

In my experience, less than 5% of patients request enhancements because of undercorrection, overcorrection or regression following LASIK.

To prevent: This kind of outcome is usually the result of an unrefined nomogram or insufficient examination by the surgeon prior to the surgery. So:

• Make sure your exam is thorough.
• Standardize your procedure.
• Refine your nomogram to ensure the best results.

To manage: If the patient doesn't achieve the desired correction, or regression occurs, perform enhancements based on the patient's individual needs. For example, if a patient is in the presbyopic age range and the final refraction is a -1 sphere OU, the patient has three choices:

• functioning with residual myopia in both eyes
• an enhancement on both eyes and the subsequent use of reading glasses
• monovision.
• hyperopic patient who is left undercorrected will usually choose to have an enhancement. You can accomplish this using either of two modalities:
• The patient can undergo LASIK a second time.
• If the degree of postoperative hyperopia is low, laser thermal keratoplasty (LTK) is another option. However, the cornea is thinner after a myopic LASIK procedure, so the spots of LTK laser energy will penetrate more deeply. To compensate, program the laser to correct half the actual amount of refractive error. For example, if a myopic patient is left with a refractive error of +2, program a correction of +1.

Dry eyes

Many LASIK patients have dry eyes preoperatively. In fact, many seek out LASIK because dry eye has made them contact lens intolerant, and spectacle correction isn't optimal.

Unfortunately, the symptoms of dry eye may become more noticeable in the months following surgery because the mechanism responsible for lacrimation has been interrupted. Also, the problem may be exacerbated because patients who've worn contact lenses and glasses for prolonged periods of time may have very sensitive eyes. (The post-op problem is often worse in peri-menopausal and menopausal women.)

To prevent: At present, the only way to minimize the chances of a patient's dry eye problem being exacerbated by LASIK is to pretreat with lubricants or punctal plugs.

To manage: Dry eye symptoms generally abate a few months after laser vision correction. Until that happens:

• Patients will have to use artificial tears until the treatment area is once again enervated.
• Should topical lubrication prove insufficient, punctual plugs may alleviate the patient's symptoms.
• Make sure patients understand that this condition exists preoperatively and may be temporarily exacerbated postoperatively. Explain that the problem will diminish over time.

Halos and night glare

Halos and night glare are often the result of the patient's pupil being larger than the treatment zone.

To prevent: Available technology can now accommodate larger treatment zones.

To manage: When halos or night glare do manifest, I reassure the patient that the problem should dissipate within the first few months after surgery. (In extreme cases, these symptoms may take up to 12 months to resolve.) I also point out that we can take steps to minimize these visual effects. Possible strategies include:

• a prescription for night driving glasses
• the use of pilocarpine (where the treatment plan allows)
• the use of colored contact lenses to create a smaller pupil.

Ectasia

Patients who are keratoconus suspects should not be considered suitable candidates for LASIK.

To prevent: Conduct a thorough evaluation before performing LASIK, including pachymetry and corneal topography, to ensure that 250 microns of corneal tissue will remain in the bed after surgery. As part of our evaluation, we routinely use the Orbscan and perform a TMS (topographic modeling system), including a keratoconus screening.

To manage: Should a patient with ectasia be referred to you, gas permeable contact lenses may be indicated. In extreme cases, corneal transplantation can be considered as a last resort.

Retinal complications

Retinal complications are not likely to be an issue unless the patient has a preoperative refraction of -8 or higher.

To prevent: Patients with refractive error in this range should receive a thorough funduscopic evaluation to detect possible peripheral retinal conditions that may require treatment prior to LASIK. We routinely refer patients in this category to retinal specialists for clearance.

To manage: If retinal complications should occur following surgery, refer the patient to a retinal specialist.

Epithelial ingrowth

This occurrence is most frequently associated with corneal abrasions and poor edge apposition at the time of the procedure.

To prevent: To avoid epithelial ingrowth:

• Minimize the use of anesthetic drops to prevent toxicity of the epithelium, which can lead to abrasions.
• Make sure you don't perform the microkeratome pass unless the cornea is moistened.
• Pay careful attention to wound apposition.

To manage: This complication needs to be addressed in the immediate postoperative period by lifting the flap and manually removing the epithelial ingrowth. Should the situation be prolonged, long-term effects could include irregular astigmatism, decreased best-spectacle-corrected visual acuity, glare and visual disturbances.

Striae

This problem results when the flap isn't properly reseated.

To prevent: Pay careful attention to wound apposition. I allow 5 minutes drying time after I'm sure that the edges of the keratectomy are in good position and aren't going to move.

To manage: Again, this must be corrected in the immediate postoperative period. To eliminate striae, lift the flap, hydrate with a hypotonic solution and reposition the flap. Otherwise, the patient may be left with a loss of best-spectacle-corrected visual acuity and debilitating visual symptoms.

Flap complications

I believe that before proceeding with the laser portion of the LASIK procedure, the diameter and thickness of the flap should be perfect. If the flap is irregular, this will be translated onto the stromal bed; the patient will end up with irregular astigmatism and a loss of best-spectacle-corrected visual acuity.

To prevent: If you detect any irregularity in the flap, place it back into position and postpone the laser portion of the procedure for 6 months. Before the secondary procedure, perform another detailed refraction and examination. (I routinely recut using a plate that's 20 microns thicker.)

To manage: If a patient comes to me with irregular astigmatism following LASIK, I advise the patient to wait for the next generation of technology. Meanwhile, fitting the patient with a rigid gas permeable contact lens is a good alternative.

Solid protocols, solid results

In my experience, when the decision to perform LASIK is based on a thorough exam and the nomogram is good, long-term problems are nearly nonexistent. When complications do appear, immediate short-term action should resolve them.

If we remain alert and do our work well, LASIK will continue to change lives for the better for many years to come. 

Sandra Belmont, M.D., is director of the Laser Vision Center and Corneal Service division of New York Presbyterian Hospital, and associate professor of clinical ophthalmology at Weill Cornell Medical Center.