Progressive corneal ectasia after laser in situ keratomileusis (LASIK)

Background LASIK (Laser in situ keratomileusis) is used in refractive surgery especially for correction of higher degrees of myopia. Preservation of Bowman's layer as well as less postoperative pain and the slight to absent subepithelial haze are regarded as advantages compared to photorefractive keratectomy (PRK). However, numerous serious complications have been described in the literature. Patients and Methods LASIK treatment was performed elsewhere in two patients to treat myopia or myopic astigmatism between -6 and -9 diopters (D). An astigmatism of -6 D was corrected with the LASIK method in another patient with keratoconus. Progressive corneal ectasia of up to seven diopters occurred in all four eyes within a few months. Conclusion Corneal ectasia can occur after LASIK even in low degrees of myopia of less than ten diopters. Recently, -12 D has been specified as the upper limit for this technique. It is especially important to rule out an early keratoconus or a forme fruste of keratoconus preoperatively since keratectasia with particularly rapid progression can occur in such cases: we would like to designate this as "malignant keratoconus".