Clinical Study Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking Natasha Pahuja, 1 Rohit Shetty, 1 Chaitra Jayadev, 1 Rudy Nuijts, 2 Bharath Hedge, 3 and Vishal Arora 4 1 Department of Cornea & Refractive Surgery, Narayana Nethralaya 121/C, Chord Road, 1st “R” Block, Rajajinagar, Bangalore, Karnataka 560 010, India 2 Department of Ophthalmology, Maastricht University Medical Center, Netherlands 3 Forus Health Pvt. Ltd, No. 2234, 23rd Cross, Banashankari 2nd Stage, Bangalore 560070, India 4 Department of Cataract & Refractive Lens Surgery, Narayana Nethralaya, 121/C, Chord Road, 1st “R” Block Rajajinagar, Bangalore, Karnataka 560 010, India Correspondence should be addressed to Vishal Arora; vish2012@gmail.com Received 13 June 2014; Revised 20 October 2014; Accepted 30 October 2014 Academic Editor: George Asimellis Copyright © 2015 Natasha Pahuja et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. To compare the penetration of ribolavin using a microscope-integrated real time spectral domain optical coherence tomography (ZEISS OPMI LUMERA 700 and ZEISS RESCAN 700) in keratoconus patients undergoing accelerated collagen crosslinking (ACXL) between epithelium on (epi-on) and epithelium of (epi-of). Methods. Intraoperative images were obtained during each of the procedures. Seven keratoconus patients underwent epi-on ACXL and four underwent epi-of ACXL. A sotware tool was developed using Microsot.NET and Open Computer Vision (OpenCV) libraries for image analysis. Pre- and postprocedure images were analyzed for changes in the corneal hyperrelectance pattern as a measure of the depth of ribolavin penetration. Results. he mean corneal hyperrelectance in the epi-on group was 12.97 ± 1.49 gray scale units (GSU) before instillation of ribolavin and 14.46 ± 2.09 GSU ater AXCL (P = 0.019) while in the epi-of group it was 11.43 ± 2.68 GSU and 16.98 ± 8.49 GSU, respectively (P = 0.002). he average depth of the band of hyperrelectance in the epi-on group was 149.39 ± 15.63 microns and in the epi-of group it was 191.04 ± 32.18 microns. Conclusion. his novel in vivo, real time imaging study demonstrates ribolavin penetration during epi-on and epi-of ACXL. 1. Introduction Keratoconus is a bilateral, asymmetric, degenerative disorder of the cornea that is characterized by progressive thinning of the stroma, leading to signiicant visual morbidity. hough the disease has been studied extensively in the past, its etiology is still unclear [1–3]. Of the various treatment options the most efective in delaying its progression is corneal collagen crosslinking (CXL) [4, 5]. he surgical technique of standard crosslinking involves removal of the epithelium to allow penetration of ribolavin into the stroma and then irradiation with ultraviolet A (UVA) light. here is still no consensus on how long the stroma should be imbibed with the solution (ribolavin 0.1% and dextran T 500 20%) in order to ensure a suicient intrastromal concentration of vitamin B2. While some groups have studied the depth of ribolavin penetration [6, 7], others have deliberated on the importance of removal of corneal epithelium during CXL [8, 9]. Use of imaging modalities like the optical coherence tomography (OCT), Brillouin microscopy, and second harmonic imaging has allowed better understanding of changes occurring in the cornea and thereby helps in predicting treatment outcomes [10–13]. hese methods, however, do not allow the assessment of tissues in vivo. We have previously compared the extent of penetration of ribolavin in epi-on and epi-of procedures with a hand held spectral domain OCT (SD-OCT, Bioptigen, Inc.) with few limitations [7]. he microscope integrated intraoperative SD-OCT is a technology that ofers continuous real time visualization of the corneal changes in vivo during surgical procedures. Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 572698, 7 pages http://dx.doi.org/10.1155/2015/572698