ARTICLE Effects of Corneal Collagen Crosslinking on Corneal Topographic Indices in Patients With Keratoconus Ibrahim Toprak, M.D. and Cem Yildirim, M.D. Objectives: To evaluate the effects of corneal crosslinking (CXL) on corneal topographic indices in patients with progressive keratoconus using Scheimpﬂug imaging system. Methods: This retrospective study comprised 59 eyes of 47 patients who underwent CXL treatment for conﬁrmed progressive keratoconus. Changes in corrected distance visual acuity (CDVA, logMAR equivalent), maximum keratometry (K), and corneal topographic indices included index of surface variance (ISV), index of vertical asymmetry, keratoconus index, center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration, and minimum radius of curvature (R min ) were analyzed at 1-year follow-up. Correlations between topographic indices and visual acu- ity were sought. Results: The study included 59 eyes of 47 patients with progressive keratoconus. The mean CDVA (P,0.001), maximum K (P,0.001), ISV, R min , and CKI (P =0.013, P , 0.001, respectively) signiﬁcantly improved after CXL treatment. Moreover, we found a signiﬁcant negative correlation between the change in IHA value and the improvement in CDVA (r = 20.351; P = 0.006). Conclusions: In patients with progressive keratoconus, cornea becomes more optically regular after CXL treatment. Changes in topographic indices might be valuable to follow-up the normalization of keratoconic cornea during the postoperative course and superior–inferior height symmetry seems to be associated with visual improvement. Key Words: Corneal collagen crosslinking—Corneal topography indices— Keratoconus—Pentacam. (Eye & Contact Lens 2013;39: 385–387) W ollensak 1 has introduced corneal collagen crosslinking (CXL) using riboﬂavin and ultraviolet (UV) A as a new hope for treatment of keratoconus. CXL as a photo-oxidative proce- dure, arrests the progression of keratoconus by increasing the biome- chanical stability of the cornea. 2 Recent clinical studies have demonstrated visual and refractive improvements after CXL in pro- gressive keratoconus and corneal ectasia. 3–5 However, under- lying mechanisms and topographic indicators of the clinical improvements after CXL treatment have not been completely determined. The Oculus Pentacam (Oculus Optikgerate GmbH, Neudorf, Germany) is a noninvasive anterior segment tomographer using 360° rotating Scheimpﬂug camera. 6 This device determines the topography and pachymetry of the entire cornea and calculates a number of indices providing information about corneal regularity from anterior curvature and elevation data. 7 In this retrospective study, we aimed to assess the changes in Pentacam topographic indices after CXL treatment, and we sought correlations between these indices and visual outcomes of the CXL treatment in patients with progressive keratoconus. MATERIALS AND METHODS This retrospective study comprised 59 eyes of 47 patients who underwent CXL for conﬁrmed progressive keratoconus. The study was performed in adherence to the tenets of the Declaration of Helsinki, and local ethics committee approved the methodology. Inclusion criteria for all patients were biomicroscopic examination and corneal topography consistent with keratoconus (inferior–supe- rior ratio .1.5), aged at least 15 years, thinnest corneal pachymetry of $400 mm, and no history of corneal scarring or surgery. Pro- gression was deﬁned as $ 1 Diopter (D) steepening of maximum keratometry or an increase of $1.00 D in manifest cylinder or an increase of $0.50 D in manifest refraction spherical equivalent in 2 years. Patients underwent detailed ophthalmological examinations included corrected (including contact lens) distance visual acuity (CDVA) measurement with Snellen charts, slitlamp biomicroscopy examination, applanation tonometry, and dilated funduscopic examination. CXL was performed under sterile conditions using topical anesthesia as described by Wollensak et al. 2 Central 9.0-mm cor- neal epithelium was removed by mechanical debridement. Isotonic riboﬂavin solution (0.1% in 20% dextran T500 solution, Medio Cross; Medio-Haus Medizinprodukte GmbH, Germany) was instilled every 2 minutes for 30 minutes until riboﬂavin absorption was observed in the corneal stroma and anterior chamber under biomicroscopic examination. Then, the cornea was exposed to UVA irradiation at the wavelength of 365 nm and surface irradi- ance of 3 mW/cm 2 (Opto XLink Corneal Cross-linking System 1.0; Opto Electronica S/A, Sao Paulo, Brazil). During the UVA expo- sure, isotonic riboﬂavin solution instillation was continued every 2 minutes for 30 minutes. Postoperatively, a soft contact lens was placed until corneal epithelial healing. Topical antibiotic and corti- costeroid drops were administered and continued 4 times daily for 1 week and 2 weeks, respectively. From the Department of Ophthalmology (I.T.), Servergazi State Hospital, Denizli, Turkey; Department of Ophthalmology (C.Y.), Faculty of Medi- cine, Pamukkale University, Denizli, Turkey; and Private Ege Akademi Eye Hospital (C.Y.), Denizli, Turkey. The authors have no funding or conﬂicts of interest to disclose. This study was performed in adherence to the tenets of the Declaration of Helsinki and Local Ethics Committee approved the study. Address correspondence to Ibrahim Toprak, M.D., Department of Ophthalmology, Servergazi State Hospital, Bereketli Beldesi, Denizli, Turkey; e-mail: ibrahimt@doctor.com Accepted June 3, 2013. DOI: 10.1097/ICL.0b013e31829e907f Eye & Contact Lens  Volume 39, Number 6, November 2013 385 Copyright @ Contact Lens Association of Opthalmologists, Inc. Unauthorized reproduction of this article is prohibited.