Corneal procedures continue to dominate refractive surgery techniques

Pre- and postoperative management of the cornea is more important than ever.

Issue: June 1, 2005

ByKenneth R. Kenyon, MD

Despite the apparent broadening spectrum of lens-based refractive surgery procedures, at least 95% of refractive surgical procedures continue to be corneal. As the complications of these procedures remain corneal, new management strategies continue to evolve.

An old but recently more high-profile issue is refractive surgery in eyes that have had prior corneal surgery. This is reflected in the subset of radial keratotomy and astigmatic keratotomy patients who have had PRK or penetrating keratoplasty. These patients are managed not only with LASIK procedures but also increasingly with laser epithelial keratomileusis (LASEK), using adjunctive mitomycin and similar treatments. Therefore, the ability to combine refractive surgical skills with corneal surgical skills must be continuously refined.

The union of refractive surgery with lens surgery has led to an emerging package of refractive lens exchange (RLE) and phakic IOLs, sometimes in concert with subsequent laser vision correction. As ophthalmologists acquire greater experience, the menu of choices increases and the limits of each procedure are better defined. This is important in terms of how to appropriately approach a certain subset of patients such as the moderate myope of presbyopic age.

Medicolegal standards have become increasingly refined with laser vision correction. If the surgeon does not objectively measure tear function, check pupil size by instrumentation, precisely measure corneal thickness and perform sophisticated topographies, the defined medicolegal standards are not met.

Ocular surface diseases, especially post-LASIK neurotrophic dry eye, are the most prevalent of surface refractive surgical problems. Although these are becoming more predictable, the problem underlines the significant relationship between the cornea specialist and the refractive surgeon.

New technologies, treatments

Refractive surgery is the new wave, while with keratoplasty is somewhat moving back.

There has been much progress with wavefront and custom laser vision correction, although one has to question the cost-benefit relationship of the custom correction in routine cases. This depends on the economics and demographics of the practice. LASEK is seemingly more than a trend; therefore, as we consider how to de-epithelialize and re-epithelialize the surface, managing these types of surface problems is critical.

Another interesting development is the resurgence of lamellar keratoplasty in several incarnations including anterior lamellar keratoplasty, deep dissection and posterior keratoplasty. Approximately 40,000 keratoplasty procedures are performed each year, and the increasing challenge is visual rehabilitation, largely the correction of regular and irregular astigmatism. This has led to the use of astigmatic keratotomy, as well as LASIK, and the trend is now shifting toward LASEK. The use of toric IOLs has also become an attractive choice that has shown positive results in Europe.

There has been some exciting progress with keratoconus management, such as the occasional use of Intacs (Addition Technologies) segments to stabilize a mild cone. The increasing application of custom LASIK in Europe and in South America is also provocative, though it is still too soon to predict the full possibilities of this as well.

Refractive lensectomy shows much promise, as well as phakic IOLs. As a cornea specialist, I am concerned about endothelial cell loss but that may prove to be a non-issue.

Regarding presbyopia, the accommodative and multifocal IOL options continue to evolve. Whether we will ever know if scleral expansion is effective is still questionable. Monovision LASIK, on the other hand, is clearly established and continues to be a benchmark.

Contact lenses are considered the corneal surgeon’s silent partner because we are not able to cure all corneas, even with customized surface ablation. The improved contact lens materials are extraordinary. Some of the new contact lens choices have no impedance of oxygen flow and permit extended wear without the effects of hypoxia. Contact lens fitting options, including the use of topographic instrumentation, are beneficial to the patient.

Surface disease treatments

There is a plethora of medications to treat ocular surface disease. Ocular surface disease medications have been a boon for the pharmaceutical industry, although this year has not shown the emergence of any breakthrough drugs. However, the allergy medications available have a multiplicity of effects, as well as the new glaucoma medications.

Treatments worth mentioning for dry eye patients are the tear drops, especially the preparations that are not just new balanced salt solutions but can restore lipids. Testing with FK-506 eye drops and other generations of immunosuppressive medications is of interest. However, the caveat is that with more drugs in our polypharmacy, there is a heightened risk of ocular surface toxicity, allergy and limbal stem cell deficiency.

It has been just 20 years since the first limbal autografts were performed. Strategies have evolved for promoting the healing of persistent epithelial defects and the reconstruction of the ocular surface by limbal grafting, adjunctive use of amnion membrane and transplantation. A potential breakthrough resulting from testing in Europe is an extract of the beneficial aspects of amnion. Hopefully, this will arrive at our shores as well.

Future of education, practice

Important factors currently influencing the practice include the economy and the legal environment. A paradigm shift has been occurring in how we can use our time more efficiently. There will be major volume increases with cataracts due to improved technology and efficiency, which allows each of us as surgeons to accomplish more.

There is an educational change emerging. We are seeing programs, especially at the fellowship level, that include the highest levels of training in cornea, cataract, refractive and even some glaucoma. Given the drive of these new techniques and technologies, students must acquire this whole package of skill sets and instrumentations to operate a fully functioning practice.

For Your Information:

Kenneth R. Kenyon, MD, can be reached at Eye Health Vision Centers, 51 State Road, North Dartmouth, MA 02747; 508-994-1400; fax: 508-992-7701. Dr. Kenyon has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.