CLINICAL SCIENCE Corneal Tomographic Changes After UV Cross-Linking for Corneal Ectasia (1-Year Results) Zainab Baksoellah, MD,*† Itay Lavy, MD,*† Lamis Baydoun, MD,*† Hilde C. M. Hooijmaijers, BHealth,*† Korine van Dijk, BHealth,*† and Gerrit R. J. Melles, MD, PhD*† Purpose: To evaluate changes in maximum keratometry (Kmax), corneal higher-order aberrations (HOAs), and densitometry (back- scattered light) up to 1 year after UV cross-linking and their possible relation with changes in the visual outcome. Methods: Retrospective cohort study on 18 eyes of 16 patients, who underwent UV cross-linking after the Dresden protocol for progressive keratoconus or ectasia after laser-assisted in situ keratomileusis. Corrected distance visual acuity (CDVA), Scheimpflug-based corneal tomography, mean image brightness (corneal densitometry) from the anterior 120 mm of the midcornea, and posterior 60 mm of the central 6 mm of the cornea, and HOAs were evaluated. Results: Kmax at 1 month (59.7 6 6.0D) after UV cross-linking resembled preoperative Kmax (59.3 6 6.4D, P = 0.368), decreased until 3 months postoperatively (58.3 6 6.3D, P = 0.002), and stabilized thereafter (P . 0.227). All postoperative corneal densitom- etry values were higher than preoperative values in all measured depths (P , 0.05). One-month anterior and total corneal HOAs (4.28 6 1.64 mm and 3.87 6 1.62 mm, respectively) resembled preoperative values (4.10 6 1.70 mm and 3.67 6 1.62 mm, respectively; P . 0.221) and then decreased until 12 months postoperatively (3.86 6 1.84 mm and 3.40 6 1.80 mm, respectively; P , 0.005). Thinnest point thickness decreased from before (442 6 25 mm) to 3 months postoperatively (427 6 25 mm, P , 0.001), with no difference at 12 months postoperatively compared with preoperative values (437 6 29 mm, P = 0.149). CDVA and endothelial cell density remained unchanged (P . 0.345 and P . 0.257, respectively). No relations were found between CDVA and the evaluated parameters (P . 0.05). Conclusions: One year after UV cross-linking, the observation of stable CDVA and thinnest point thickness, together with reduced Kmax suggests no ectasia progression within the study period in these cases. Although HOAs showed a trend toward improvement, corneal densitometry remained elevated. Key Words: keratoconus, progression, UV cross-linking, densitometry, higher-order aberrations (Cornea 2017;0:1–5) K eratoconus is generally described as a noninflammatory condition of the cornea, which usually starts in adoles- cence and is characterized by continuous steepening and thinning of the cornea, known as keratectasia, resulting in corneal protrusion with irregular astigmatism and significant deterioration of visual quality. 1,2 Keratectasia may also develop after uneventful laser-assisted in situ keratomileusis (LASIK), most likely triggered by disruption in corneal biomechanical integrity. 3 In early stages of the disease, irregular astigmatism may be managed with spectacles and later by different types of contact lenses. However, with progression of the ectasia and further deformation of the cornea, contact lens wear may become difficult, sometimes resulting in contact lens intoler- ance. 1,2,4 Currently, UV cross-linking is a widely used treatment to delay progression and possibly avoid the need for more invasive treatments such as Bowman layer trans- plantation, deep anterior lamellar keratoplasty, or penetrating keratoplasty in eyes with mild to intermediate stages of progressing keratoconus or post-LASIK ectasia. 4–9 Evaluation of corneal ectasia is commonly performed through corneal topography and pachymetry taken at consec- utive follow-up visits. In recent studies, also other parameters such as corneal backscattered light and higher-order aberra- tions (HOAs) were suggested to be useful in the assessment of keratoconus and other corneal ectatic diseases because these parameters might also give refined insight into the optical quality of the cornea in contrast to corneal topography and pachymetry alone. 10–12 In this study, we evaluate the effect of UV cross-linking on corneal tomography parameters, corneal backscattered light, and HOAs up to 1 year after UV cross-linking. MATERIALS AND METHODS Eighteen eyes of 16 patients (12 men and 4 women), with a mean age of 32 (69) years (range 19–51 years), who underwent UV cross-linking for progressive keratoconus Received for publication May 22, 2017; revision received July 6, 2017; accepted July 10, 2017. From the *Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; and †Melles Cornea Clinic Rotterdam, Rotterdam, the Netherlands. G. R. J. Melles is a consultant for DORC International/Dutch Ophthalmic USA and SurgiCube International. L. Baydoun is a consultant for DORC International/Dutch Ophthalmic USA. The remaining authors have no funding or conflicts of interest to disclose. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.corneajrnl.com). Reprints: Gerrit R. J. Melles, MD, PhD, Netherlands Institute for Innovative Ocular Surgery, Laan op Zuid 88, 3071AA Rotterdam, the Netherlands (e-mail: research@niios.com). Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. Cornea  Volume 0, Number 0, Month 2017 www.corneajrnl.com | 1 Copyright Ó 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.