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Clinical Update: Refractive
The Ocular Surface Before LASIK: Preop Care Prevents Postop Problems
By Lori Baker Schena, Contributing Writer
 
 

Ironically, many patients who seek out refractive surgery—especially those who cannot tolerate contact lenses because of dry eyes—may be the ones most vulnerable to postsurgical problems.

“Dry eye is ubiquitous, and long-term contact eye wear can either cause it or make it worse,” said Ernest W. Kornmehl, MD, medical director, Kornmehl Laser Eye Associates in Boston. “Most patients will be drier three to six months following LASIK because the corneal nerves are severed, which is why it is imperative that ocular surface health be aggressively addressed prior to surgery.”

Obvious, yes, but. While this may sound like common sense, focusing on ocular surface health can be easier said than done. “Oftentimes, patients have thought long and hard about undergoing refractive surgery, and when they finally present at your office, they want to schedule the procedure as quickly as possible,” noted Sonia H. Yoo, MD, assistant professor of ophthalmology and cornea fellowship director at the Bascom Palmer Eye Institute. “Yet this is when you need to counsel patience, educating patients that ocular health must be addressed to optimize their outcome, even if this means weeks or months of presurgical treatment.”

Edward E. Manche, MD, associate professor of ophthalmology and director of the cornea and refractive surgery service, Stanford University, explained that refractive surgery causes a wound to the cornea, and prior ocular health impacts how it will heal.

Survey the Surface
The first step in ensuring ocular surface health is a thorough ocular evaluation. Dr. Kornmehl is so concerned about ocular surface health that he insists on examining each of his patients himself as opposed to delegating that responsibility. “I pick up so much external disease, and find myself managing a large percentage of patients with dry eye,” he said. “A thorough preoperative examination is crucial in achieving an excellent result in an informed, happy patient.”

Dr. Kornmehl’s examination begins the moment the patient walks into the room. He first looks at the patient’s face for any signs of rosacea, a chronic disease characterized by facial telangiectasias, pimples and, in advanced stages, thickened skin. In addition to skin problems, a large percentage of these patients experience eye problems associated with meibomian gland dysfunction. Symptoms and signs may include burning, lacrimation, foreign-body sensation, pruritis and ocular injection. The eyelids may become inflamed and swollen as well. “Sometimes just seeing the telltale signs of rosacea may be a warning for ocular surface problems, some of which could be subclinical,” Dr. Kornmehl said.

Consider the not-so-obvious. Dr. Manche likened this physical examination to “detective work,” as many ocular surface problems simply are not readily apparent, and patients are often at a loss to describe their symptoms. “This is especially true in older patients who come in complaining of itchy, scratchy eyes. They actually won’t say they have dry eye—they may not recognize the symptoms—but they can no longer wear contact lenses,” said Dr. Manche. “When you hear that history, it is imperative to be particularly observant.”

It is also vital to discover which drugs the patient is taking, as antihistamines and some antidepressants can create a dry surface that is not amenable to LASIK. Dr. Kornmehl mentioned nocturnal lagophthalmos as a potential cause of corneal problems as well.

One of the more obvious red flags discovered during slit-lamp examination is anterior basement membrane corneal dystrophy, which can lead to recurrent corneal erosion, Dr. Manche added. Fluorescein ocular testing is also essential; this is often necessary to detect problems with the cornea and conjunctiva. 

Since dry eye problems can be subclinical, noted Dr. Yoo, it is important that patients with persistent problems undergo a Schirmer test to evaluate aqueous tear production. “Without a doubt, older patients produce fewer tears so that should be part of the preoperative evaluation—assessing tear production.” Other things that may be missed include basement membrane dystrophy or loose epithelium. “These are subtle, but could cause problems during or after surgery,” she added.

Refresh With Drops and Plugs
Management of the ocular surface is directly related to the cause of any underlying problem, Dr. Kornmehl noted. For instance, if the patient is suffering from a simple case of dry eye with no inflammation or lid disease, Dr. Kornmehl may start the patient on topical lubrication with nonpreserved tears and ointment and dissolvable punctal plugs that last three to four months. If the patient has lid disease, however, he will give them cyclosporine ophthalmic drops, warm compresses and, potentially, doxycycline. Punctal plugs can be inserted once the lid disease is under control.

Patients need patience. Although the patient may experience some relief within a week of use, the medication achieves its full effect after at least three months of continuous use—which is in sync with Dr. Kornmehl’s assertion that managing the ocular surface prior to LASIK takes time and patience—something patients may be short of in many instances. If medication is ineffective, Dr. Kornmehl may then insert silicone punctal plugs. He may prescribe both upper and lower plugs if required.

“Again, the key factor here is counseling patients so they don’t become discouraged,” Dr. Manche said. “Many of these treatments may take several weeks to a month or two for the desired effect.”  Dr. Manche suggests his patients take supplements such as flaxseed oil. “While some people swear by them, other people have not had any improvement, so my experience is inconclusive. However, as long as it is not going to do harm, then the patient may choose to try them.”

Dr. Kornmehl takes care to communicate to patients that dry eye will not disqualify someone from receiving LASIK if their ocular surface responds to treatment preoperatively. However, they can expect some moderate discomfort for several weeks after the procedure.

Alternatives to LASIK
Finally, there are a group of patients who will have some degree of chronic irritation that cannot be completely eliminated. “In those patients, quite frankly, I dissuade them from undergoing refractive surgery,” Dr. Manche said. “Indeed, there are a good number of people out there that, despite everything you do, you cannot get them to a point where they are comfortable. Those people are at risk for extensive problems following LASIK surgery.”

Dr. Yoo noted that while some patients may not be candidates for LASIK, they may be amenable to other refractive procedures. “In LASIK, we are cutting a flap through the nerves, and it takes longer for those nerves to regenerate,” she explained. “Corneal nerves seem to regenerate more quickly after LASEK or PRK.”

Ablation option. “So, for example, if patients have loose epithelium, the surgeon may choose to do a surface ablation —removing the epithelium and lasering on the surface,” Dr. Yoo said. “That may be a procedure that you would choose over LASIK when you wish to replace the old epithelium.” She cited another instance in which patients experienced an infection or a foreign body that left a superficial opacity or scar on the cornea. “Surface ablation could be used to eliminate the opacity as well as the refractive error,” she said. “In essence, there may be one procedure that would be more appropriate than another.

“This is why it is important for physicians to see patients prior to surgery and evaluate subtle things that may be missed in an earlier screening,” said Dr. Yoo. She warned that many ophthalmologists focus almost entirely on refractive error issues during initial appointments, to the exclusion of ocular surface issues. And sometimes patients may forget to mention ocular surface problems or may be asymptomatic. 

Ounce of Prevention: Pound of Cure
Dr. Yoo said that many referrals to her practice for postoperative problems are the direct result of issues that have not been identified prior to surgery. “Sometimes you can’t know everything in advance, such as patients with borderline dry eye who then have an exacerbation of dry eye postsurgically,” she said.

Dr. Manche added that even those patients who are treated for ocular surface problems preoperatively will still experience postoperative denervation and can expect drier eyes for a few weeks or even a few months. “The real advantage to rehabilitating the surface prior to surgery is that if the ocular surface is healthy, the post-LASIK course will go much more smoothly,” he said. “However, if you totally ignore it, it will be incrementally more difficult to rehabilitate the ocular surface following surgery. And we all want to avoid these pitfalls.”