Refractive Surgery Correcting the Irregular Cornea

AUGUST 2011 CATARACT & REFRACTIVE SURGERY TODAY 31 P rogressive, asymmetrical corneal steepening associated with an increase in myopic and astigmatic refractive errors, combined with midperipheral and/or peripheral corneal thinning, represents a constellation of findings in ectatic corneal disorders (eg, keratoconus and pellucid marginal degeneration). These entitites are associated with asymmetry upon presentation, unpredictability of progression, and myriad abnormal topographic findings. Similar observations after LASIK surgery have been described as post-LASIK ectasia.1-3 Analyses of series of eyes that have developed post-LASIK ectasia have suggested that certain preoperative and/or operative features may be associated with this adverse outcome of LASIK or PRK.4 The fact that ectasia can occur in the absence of these features, or that it may not occur in spite of them, has confounded surgeons’ understanding of this complication.5 Nevertheless, post-LASIK ectasia is a visually disabling complication whose ultimate surgical treatment is penetrating keratoplasty when glasses or contact lenses can no longer provide patients with visual quality that allows them to perform their activities of daily living. During the past 10 years, the use of topical riboflavin combined with ultraviolet-A (UVA) irradiation to increase collagen cross-linking (CXL) has demonstrated the potential for retarding or eliminating the progression of keratoconus and post-LASIK ectasia. My colleagues and I have previously reported on the application of CXL in post-LASIK ectasia.6 We have found that once the progression has stabilized, it is possible to treat the surface of the eye with customized PRK to normalize the corneal surface by reducing irregular astigmatism. After using CXL for cases of ectasia, my colleagues and I introduced the Athens Protocol, which consists of same-day, topography-guided partial PRK and CXL.