EyeWorld Asia-Pacific June 2017 Issue

June 2017 EWAP CORNEA 43 Top 10 recommendations for preventing complications in corneal refractive surgery Dr. Bernal shares tips to avoid complications F or over 25 years, excimer laser refractive surgery has been the prevailing choice for patients with refractive errors who are candidates for this type of surgery. During that time, we have gained a lot of knowledge and become much more selective in choosing the right candidate for a specific procedure. Sometimes it is difficult to determine who should not undergo this type of surgery. Here are 10 recommendations for avoiding complications with these procedures. 1. Avoid LASIK in patients with flat corneas. Regardless of pachymetry results, a patient with a keratometry reading below 40 D represents a risk for intraoperative complications, which can easily be avoided by switching to PRK. Procedures using femtosecond laser can find a niche among these patients with femto-LASIK, small incision lenticule extraction (SMILE), or ReLEx SMILE (Carl Zeiss Meditec, Jena, Germany). 2. Use mitomycin-C for all PRK cases. Many Latin American countries are very near the equator, where the sun’s intensity is much greater and constant than in more distant latitudes. We have encountered haze even in very small ablations. Although this complication can be solved in most cases with topical treatment and does not affect the refractive outcome or the patient’s vision, in some instances we have seen the need for a more aggressive surgical treatment. Since implementing the use of mitomycin-C in all PRK cases, our haze rate has decreased considerably. 3. Avoid PRK in bitoric ablations. Even with the use of mitomycin-C, there is a greater incidence of regression and high risk of haze. 4. If a deep cut is present, preventing treatment, it is advisable to suspend surgery in that eye and wait to complete it later. If the surgeon feels confident, he or she can perform the procedure in the other eye after checking the equipment to ascertain that there are no issues. Likewise, we recommend that treatment be performed with PRK to avoid any unnecessary risks. 5. It is important to consider cycloplegic refraction data in farsighted patients and to plan a treatment that covers most of this refraction, despite the initial symptom of transitory nearsightedness. This will ensure more lasting results in this group of patients. 6. Do not use a microkeratome in older adults. This procedure has been associated with a greater risk of macular neovascularization. Usually, when we decide to treat older adults with excimer laser it is for a pseudophakic patients, and the refractive error is not so high that it cannot be treated with PRK. It is also important to take into account that this group of patients usually suffers from varying degrees of dry eye. 7. In aberrometry-guided treatments, particularly when using full-eye wavefront refraction , it is advisable to assure a pupillary aperture that is equal or greater to the optical zone. Extended ablations are extrapolations which do not always conform to the surgical plan and can diminish the desired effect. 8. Reducing the optical zone in order to correct more diopters is usually a bad idea. Patients evaluated using dynamic pupillometry with similar mesopic and photopic conditions may be the exception. In the majority of cases, if it is necessary to modify the optical zone, it may be a better idea to consider a phakic lens to achieve a better result. 9. Treatment of significant flap folds should be performed as soon as possible. It is important to de-epithelize the edge of the cut in order to avoid seeding, and waiting several days could make it impossible to properly smooth out the interface. 10. In the event of an irregular cut with loss of tissue, it is important to allow sufficient time for the cornea to stabilize itself . Once refractive stabilization is achieved, an aberrometry-guided PRK can be performed. These patients can benefit greatly from an anterior lamellar transplant for 150 µm. Photorefractive keratectomy can even be performed over the new lamella. A more conservative but equally effective alternative would be the use of a gas permeable contact lens. EWAP Editors’ note: Dr. Bernal has no financial interests related to his comments. This article originally appeared in Spanish in ALACCSAR-R News, September–October 2016, p. 25. It was translated by Creative Latin Media, Bogotá, Colombia, and is used here with permission from ALACCSA (Latin American Society of Cataract and Refractive Surgeons). Contact information Bernal: claros@videre.com.mx by José Antonio Claros Bernal, MD