Mastering Endothelial Keratoplasty DSAEK, DMEK, E-DMEK, PDEK, Air pump-assisted PDEK and others Volume II Soosan Jacob Editor 123 Mastering Endothelial Keratoplasty Soosan Jacob Editor Mastering Endothelial Keratoplasty DSAEK, DMEK, E-DMEK, PDEK, Air pump-assisted PDEK and others Volume II Editor Soosan Jacob Director and Chief Dr Agarwal’s Refractive and Cornea Foundation Dr Agarwal’s Group of Eye Hospitals Chennai India ISBN 978-81-322-2819-6 ISBN 978-81-322-2821-9 DOI 10.1007/978-81-322-2821-9 (eBook) Library of Congress Control Number: 2016945973 © Springer India 2016 This work is subject to copyright All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed The use of general descriptive names, registered names, trademarks, service marks, etc in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer (India) Pvt Ltd For Dad and Mom “No matter how far we come, our parents are always in us.” -Brad Meltzer Foreword It is my pleasure really to write a few words as a foreword for this two-volume book on endothelial keratoplasty led by Dr Soosan Jacob As a cornea surgeon for the last 20 years, I have personally experienced the evolution of surgical visual rehabilitation of patients with corneal endothelial disease and/or trauma My training and early practice was focused on penetrating keratoplasty It was through the work of great innovators in our field of cornea transplantation surgery that endothelial keratoplasty techniques were introduced and popularized Endothelial keratoplasty techniques currently account for the majority of cornea transplantation procedures performed in the USA and many other countries around the world The advantages in safety and accelerated efficacy with endothelial keratoplasty techniques are enormous It only takes one intraoperative suprachoroidal hemorrhage during an opensky graft, or an inadvertent trauma in a successful penetrating keratoplasty, resulting in a wound dehiscence and catastrophic intraocular structure(s) expulsion to appreciate this The journey in the development of these techniques has been colorful and rapid! DLEK was probably the earliest innovation, with DSAEK next, and later, DMEK, PDEK and DMET Dr Jacob has been one of those pivotal innovators and early adaptors, as a keen surgeon and passionate clinician enriching the current status quo of cornea surgery with many innovative concepts and techniques Her commitment not only to patient care but also to academic medicine has brought to fruition this cornea transplantation “encyclopedia” Dr Jacob has generously recruited the significant contributions of many other leading experts and innovators from all around the globe, generating a complete journey for the anterior segment surgeon reader through anatomy, history, technique, technology, complications and their management I think the ophthalmic vii viii Foreword community is indebted to her for this brilliant text, and I am personally grateful to use it as a reference guide myself! Enjoy the knowledge, passion and brilliance of our colleagues in action A John Kanellopoulos, MD Clinical Professor of Ophthalmology, NYU Medical School New York, NY Medical Director: The Laservision Clinical and Research Institute, Athens, Greece President: The International Society of Refractive Surgery-Partner of the American Academy of Ophthalmology Preface The landscape of cornea as a sub-speciality has changed significantly from the past Technology has improved by leaps and bounds and new techniques are constantly evolving Interlinking of technology, newer surgical techniques, and basic research has brought about rapid shifts in our approach to corneal surgery, especially keratoplasty Lamellar keratoplasty, both anterior and posterior, have shown such improved results that they have become the standard of care The last two decades have seen the introduction of posterior lamellar keratoplasty as well as many changes in the way it has been performed Endothelial keratoplasty has today become the most popular of choices for endothelial dysfunction requiring surgery In 2011, about half the corneal transplants performed in the USA were Descemet stripping automated endothelial keratoplasty (DSAEK), and in 2012 it overtook penetrating keratoplasty in terms of the number of corneas being used The acceptance is similar in many other parts of the world The reason DSAEK is finding favor with both surgeons and patients is because of the improved recovery times and visual outcomes as well as the numerous intra-operative advantages However, despite the even greater perceived advantages of the two more recent forms of endothelial keratoplasty – Descemet membrane endothelial keratoplasty (DMEK) and Pre-Descemet endothelial keratoplasty (PDEK) – there is still hesitancy on the part of many corneal surgeons to the inclusion of these into their surgical armamentarium This is because these are perceived as more challenging techniques with a greater learning curve This two-volume book on endothelial keratoplasty (EK) serves to fill up a vacuum in this space as there is at present no book that covers all kinds of EK including DSAEK, ultra-thin DSAEK (UT-DSAEK), DMEK, and PDEK It has been aimed to serve as an excellent guide for DSAEK to both the beginning surgeon as well as those who need a refresher to sharpen their skills further It also at the same time serves as a stepping stone for successfully, and with minimal heartburn, mastering the more challenging newer endothelial keratoplasties, viz., DMEK and PDEK The various minute steps that are essential for these as well as for newer ancillary techniques which help make surgery easy such as endoilluminator assisted DMEK (E-DMEK) and the air-pump assisted PDEK have been described in detail The ix 13 Targeting Emmetropia in Endothelial Keratoplasty 207 Techniques and Technology Dry Eye Target Punctal Plugs Monofocal Thermal pulsation Monovision PRK/ASA Toric LASIK Multifocal Ocular Surface Pterygium removal Accomodative Phakic Implants ICL Anterior – VERISYS] Lasik Vision Surgery ICL Posterior – VISIAN ALK Cornea INTACS Collagen cross linking DSAEK PKP Cataract Surgery Monofocal Toric Fig 13.1 The Gulani 3T system which helps understand and select the right technique, technology, and vision target for each patient cases of corneal diseases were commonly treated with PK, a form of transplant that involved a full thickness cornea, but as medicine advanced, alternative surgical techniques, such as DSEK/DSAEK, DMEK, and now, PDEK, have been the preferred treatment method [6] (Fig 13.2a–h) Descemet’s stripping endothelial keratoplasty (DSEK) and Descemet’s stripping automated endothelial keratoplasty (DSAEK) have become a promising treatment method for advanced corneal disorders [6, 7] These transplant surgeries have proven to reduce the postoperative recovery period, lessen graft complications and rejections, and provide better postoperative visual acuity and corneal function 13.2 DSEK DSEK is one of the modalities of EK that is performed by eye surgeons all over the world DSEK is the preferred choice of surgery because it is fairly easy to perform and provides promising outcomes This surgery involves the removal of a small 208 A.C Gulani a b c d e f g h Fig 13.2 (a) The PBK cornea; (b) paracentesis made at 11 and o’clock; (c) single instrument inserted for scoring seen here; (d) same instrument peels and rolls the Descemet’s membrane out through paracentesis (as seen in the image); (e) checking complete 8.5 mm removal of Descemets by unfolding on top of cornea; (f) inserting donor cornea; (g) air bubble to inflate AC; (h) air bubble decreased with BSS exchange and suture less incision covered by conjunctiva 13 Targeting Emmetropia in Endothelial Keratoplasty 209 Fig 13.3 A case of DSAEK surgery was referred with anterior corneal irregularity and scarring Amniotic membrane resurfacing following lamellar keratectomy resulted in a clear cornea portion of the posterior corneal stroma, the dysfunctional corneal endothelial layer, as well as the basement membrane, Descemet’s membrane, which the endothelial cells are attached to [6, 7] 13.3 DSAEK DSAEK is practically similar to DSEK, except for the use of a machine to automatically address the cornea DSEK and DSAEK involve a thicker corneal transplant compared to the ones used during Descemet’s membrane endothelial keratoplasty (DMEK) [6] (Figs 13.3 and 13.4) 13.4 DMEK Many technical modifications and improvements are flourishing DMEK’s emergence as DSEK/DSAEK’s contender DMEK is currently in the works of becoming the favored corneal endothelial transplant technique DMEK, contrary to DSEK/ DSAEK, only strips the Descemet’s membrane (DM) with the endothelial cells resulting in the need for a thinner and more fragile donor graft [3] One of the drawbacks eye surgeons found in DMEK was the handling and insertion of the delicate donor graft Because the graft is so thin and frail, surgeons must handle it with caution in order to keep from damaging the endothelium cells Compared to DSEK/ DSAEK, inserting the donor graft into the eye is found to be challenging because of the delicacy of the graft [6, 8] Surgeons must be able to unroll the donor graft once inside the chamber of the eye, determine which side contains the DM and endothelium cells, and perfectly position the graft so that it is centered in the eye without any wrinkles [6, 8] The visual outcomes and anatomical restoration are anecdotally superior though with this technique (Fig 13.5) 210 A.C Gulani Fig 13.4 A case of bubble trouble This patient rubbed his eye and next day postop we found the bubble in the interface between the recipient and donor cornea The air bubble was manipulated with a 26-gauge needle and found its position back under the donor cornea to allow the graft to appose to the recipient Fig 13.5 A case of DMEK with lens implant; straight to emmetropia 13 Targeting Emmetropia in Endothelial Keratoplasty 211 Fig 13.6 The PDEK bubble (Courtesy, Dr Soosan Jacob, Dr Agarwal’s Eye Hospital, Chennai, India) 13.5 PDEK In recent times, Dr Harminder Singh Dua made a contributing discovering of a previously undetected layer of the cornea [9, 10] This thin, yet tough layer was later named after the discoverer as Dua’s layer Dua’s layer lies between the corneal stroma and Descemet’s membrane The tough characteristic of Dua’s layer is due to the fibrous tissue that makes up this layer Because the layer is tougher, it is easier to manipulate and reduces the chances of collateral damage to the cornea The discovery of this new corneal layer has led to the innovation of a new endothelial keratoplasty technique, pre-Descemet’s membrane endothelial keratoplasty (PDEK) by Agarwal et al [9, 10] Unlike DMEK, which uses a thin, fragile donor graft, PDEK utilizes an extra layer, Dua’s layer, in the graft, which permits surgeons more freedom with handling and inserting the graft in the eye without struggle Also, the donor graft used for PDEK can be obtained from donors of any age, preferably younger donors Earlier corneal grafts were obtained from donors aged 50 and over [9, 10] The tougher Dua’s layer also aids the surgeon to perform the EK with more liberty and ease, compared to other modalities of EK PDEK procedure is similar to DSEK and DMEK with slight variations to accommodate for the extra layer being removed and replaced (Fig 13.6) With the surgical evolutionary escalation of the abovementioned modalities, endothelial keratoplasty has achieved a paradigm shift in corneal transplant surgery wherein most of the Corneoplastique™ principles [11–13] are already being followed Add to this an unrelenting mindset of concluding with improved vision using refractive surgery principles and the bar is now raised from the surgical evolution of endothelial keratoplasty to heightened visual outcomes The entire thought process of raising the bar on endothelial keratoplasty to a refractive outcome should be initiated and sustained at all levels of preoperative planning, surgery, and follow-up 212 13.6 13.6.1 A.C Gulani Gulani Refractive Descemet’s Endothelial Keratoplasty (REFDEK) Classification Preoperative In patients with Fuchs’ dystrophy, I suggest earlier cataract surgery in order to remove a softer lens (hence less phaco energy which good damage the already compromised endothelium) This could allow us to nearly neglect the existence of associated Fuchs’ dystrophy and plan for emmetropia by additionally providing premium lens implant options which may not be the case with more advanced Fuchs’ dystrophy in the late future 13.6.2 Intraoperative Though endothelial keratoplasty is already an advancement on penetrating keratoplasty, we can further refine and elevate this surgery to being refractively neutral or even corrective using well planned steps during surgery itself A The main incision could be made posterior to the limbus or a frown scleral incision that not only is self-sealing but also astigmatic ally neutral B Minimal manipulation of tissues with good alignment and intrinsic care to prevent wrinkles in the donor cornea or edge discrepancy between donor recipients C The drainage incisions made on the recipient cornea anteriorly could be performed on the steep axis (as predetermined by preoperative topography and refraction) acting like mini limbal relaxing incisions to not only help drain the fluid between the donor and recipient graft interface but also correct coexistent astigmatism D If the patient is pseudophakic, maintain the stability of the anterior chamber and prevent dislodgment or decentration of the lens implant and also check to make sure it is still in the capsular bag nicely secure to prevent any refractive shift E Do remember the Barraquerine principle of lamellar corneal surgery wherein the addition of donor graft will move a refractive status to a relatively hyperopic direction (this principal is also important when doing a combined case to make sure to plan for a matching myopic outcome to compensate for this hyperopic directive) F Intraocular lens implants including premium lens implants like toric lenses can be confidently chosen once sufficient confidence is achieved with consistent refractive outcomes of your own endothelial keratoplasty techniques G Avoid sutures if you can (and thus avoid adding astigmatism) and hydrate to close all incisions which were minimal to begin with This can further be facilitated with recently approved wound sealants like ReSure® H Facilitate rapid epithelial healing to determine refractive status (Figs 13.7 and 13.8) 13 Targeting Emmetropia in Endothelial Keratoplasty 213 Fig 13.7 Poorly done DSAEK or failing endothelial keratoplasty can be rejuvenated and enhanced using REFDEK principles Fig 13.8 Endothelial keratoplasty (REFDEK) in a case of radial keratotomy 13.6.3 Postoperative A Excimer Laser ASA (advanced surface ablation) can be used to correct residual refractive errors to emmetropic outcomes (Fig 13.9) B Lens implant-based optical manipulations can be undertaken, i.e., piggyback lens, toric lens rotation and only if needed, lens exchange surgery too as we would in any patient expectant of refractive outcomes (Fig 13.10) C Miscellaneous: Given proper indications, I not see a contraindication to even using collagen cross-linking in cases of endothelial keratoplasty in RK cases once refractively stable or touch of procedures like astigmatic keratotomy, Femto laser astigmatic keratotomy, conductive keratoplasty, etc In summary then, excited as we are about the surgical evolution of endothelial keratoplasty from DSEK to DMEK and PDEK, let us also raise the bar on ourselves and deliver vision at the highest level we can through this exciting procedure once again not only in restoring anatomic function but also vision outcomes With technologies today ranging from new-generation excimer lasers, femtosecond technology, lens implants with individualized optics, refractively fine tuning procedures, and permanizing techniques like collagen cross-linking, we can truly live up to ever-enchanting properties of the cornea which not only provides 214 A.C Gulani Fig 13.9 The patient in Fig 13.4 at months underwent laser vision surgery to 20/20 uncorrected vision Fig 13.10 Toric lens implant with endothelial keratoplasty planned to emmetropic outcome transparency to see the outside world but also has the optical power to focus our vision [14–16] May I take this opportunity then to reiterate my respects to our cornea by calling it our “Vision rehabilitative platform!” 13 Targeting Emmetropia in Endothelial Keratoplasty 13.7 13.7.1 215 My Personal Techniques Minimal DSAEK Surgery: Gulani Key Hole Transplant (REFDEK) (i) Specifics: topical anesthesia, sutureless superior incision, single instrument surgery (ii) Advantages: • Since most of the referred cases of PBK have had cataract surgery with a temporal incision, my preferred approach is a superior limbal incision which allows me to operate in an untouched area with good self-sealing incision architecture This area also is cosmetically under the upper lid and therefore next day postop these patients look like they have had no surgery • Single instrument (Gulani scorer and peeler) allows for less tissue manipulation and elegant working in a closed system, double paracentesis arena (until the main incision is entered) • Topical anesthesia allows for faster recovery and ocular medication toward an encouraging outcome • Sealant option if needed (Fig 13.11) Fig 13.11 ReSure sealant was used in this case for excellent refractive and anatomic outcome 216 A.C Gulani References Facts about the cornea and corneal diseases National Eye Institute National Institutes of Health, May 2013 Web 28 Oct 2014 http://www.nei.nih.gov/health/cornealdisease/ Cassin B, Solomon S Dictionary of eye terminology Gainesville: Triad Publishing Company; 1990 Sayegh F The correlation of corneal refractive power, axial length, and the refractive power of the emmetropizing intraocular lens in cataractous eyes Ger J Ophthalmol 1996;5(6):328–31 PubMed Web 28 Oct 2014 http://www.ncbi.nlm.nih.gov/pubmed/9479513 MerindanoEncina MD, Potau JM, Ruano D, Costa J, Canals M A comparative study of Bowman's layer in some mammals relationships with other constituent corneal structures Eur J Anat 2002;6(3):133–40 Corneal conditions Cornea Research Foundation of America Web Oct 2014 http://www cornea.org/index.php/research/corneal_conditions Stodola E Cornea surgeons compare thin DSAEK and DMEK as options for endothelial keratoplasty procedures EyeWorld Jan 2013 Web 28 Oct 2014 http://www eyeworld.org/article-cornea-surgeons-compare-thin-dsaek-and-dmek-as-options-forendothelial-keratoplasty-procedures Fernandez M, Natalie A How to perform Descemet’s stripping automated endothelial keratoplasty American Academy of Ophthalmology EyeNet Magazine, Jan 2007 Web 28 Oct 2014 http://www.aao.org/publications/eyenet/200701/pearls.cfm Shaw J DMEK: A new contender for corneal transplantation American Academy of Ophthalmology EyeNet Magazine, Sept 2012 Web 28 Oct 2014 http://www.aao.org/publications/eyenet/201209/cornea.cfm Agarwal A Pre Descemet’s Endothelial Keratoplasty (PDEK): A novel method of endothelial transplantation EyeWorld Jan 2014 Web 28 Oct 2014 http://www.eyeworld.org/ article-pre-descemet-s-endothelial-keratoplasty pdek a-novel-method-of-endothelial-transplantation 10 Agarwal A, Priya N PDEK: a revolution in corneal transplantation Ophthalmology Management Mar 2014 Web 28 Oct 2014 http://www.ophthalmologymanagement.com/ articleviewer.aspx?articleID=110224 11 Gulani AC Tips, insights, and techniques from other surgeons In: Price F, editor Textbook – DSEK what you need to know about endothelial keratoplasty, vol Thorofare: SLACK Inc; 2009 p 113–5 12 Gulani AC Key hole corneal transplant Surgical techniques in ophthalmology corneal surgery JP Publ 2009;25:154–6 13 Gulani AC Corneoplastique™: art of vision surgery Indian J Ophthalmol 2014;62:3–11 14 Gulani AC Evaluating the impact of femto laser-assisted capsulotomy Cataract Refract Surg Today Eur 2014;9(2):36–50 15 Gulani AC Decoding corneal scars: straight to 20/20 Ophthalmol Times 2014;39(4):6–12 16 Gulani AC Corneoplastique Tech Ophthalmology 2007;5(1):11–20 Chapter 14 Rhokinase Inhibitors for Endothelial Decompensation Dhivya Ashok Kumar Contents 14.1 Introduction 14.2 Endothelium 14.3 Rhokinase Enzyme and Its Role 14.4 In Vitro Studies with Monoclonal Endothelial Cells (MCECs) 14.5 In Vivo Rhokinase Inhibitors 14.6 Human Trials 14.7 Conclusion References 14.1 217 218 218 219 219 220 220 221 Introduction Cornea is a unique structure with varied physiological mechanism working for its transparency and integrity Orientation of collagen, arrangements of keratocytes, fluid transport mechanism, endothelial cell function and proteoglycan proportions are some of the factors which contribute to its physical nature Conditions which hinder the above normal systematic functions are known to affect corneal transparency Corneal endothelial cell is one vital structure which is highly efficient in preserving the vitality of the corneal layers D.A Kumar, MD, FICO Consultant and Head R&D, Dr Agarwal’s Refractive and Cornea Foundation, Dr Agarwal’s Eye Hospital and Eye Research Centre, 19, Cathedral Road, Chennai, TN 600086, India e-mail: susruta2002@gmail.com © Springer India 2016 S Jacob (ed.), Mastering Endothelial Keratoplasty, DOI 10.1007/978-81-322-2821-9_14 217 218 14.2 D.A Kumar Endothelium Corneal endothelium is a 5-μm thick single monolayer of cell spread along the posterior most part of the cornea It has active pumps for ionic and fluid transport across it Conditions like trauma, congenital cell damage (Fuchs’ endothelial dystrophy or posterior polymorphous dystrophy) and post-surgery (cataract or vitreoretinal) can affect its routine function Abnormal cell morphology in normal cell count or low pre-operative cell count or endothelial damage intra-operatively can cause this It is known that endothelial cell has less potential to regenerate due to the following reasons: (1) cell-to-cell contact inhibition, (2) G1 phase arrest, (3) less response to microenvironment stimulators, and (4) TGF-B2 suppression of S phase [1] Though there are varied surgical treatment options like penetrating and endothelial keratoplasty in advance cases of corneal endothelial decompensation, only few medical management options have been tried in early cases 14.3 Rhokinase Enzyme and Its Role The Rho/ROCK pathway is known to be involved in regulating the cytoskeleton, cell migration, cell apoptosis, and cell proliferation ROCK inhibitor Y27632 specifically blocks ROCK1 (P160ROCK) Chemically, it is trans-4-(1-aminoethyl)-N(4-pyridyl) cyclohexane carboxamide dihydrochloride It has shown to have some promising effects in corneal endothelial decompensation [2–4] ROCK regulates the formation of actin stress fibres assembly and cell contraction (Fig 14.1) In addition Rhokinase Myosin light chain phosphatase Contraction ERM family P27 ERK1/2 Cell adhesion & migration Fig 14.1 Schematic picture showing the functions of rhokinase pathway Cell propagation 14 Rhokinase Inhibitors for Endothelial Decompensation 219 to the primary function in cytoskeleton remodelling and migration, Rho signalling pathway has been shown to be involved in the regulation of other biological processes like gene transcription, G1 cell cycle progression and apoptosis [5] It has been demonstrated that ROCK inhibitors use both cyclin D and p27 through PI 3-kinase signalling to promote corneal endothelial cell proliferation [6] The ROCK pathway is involved in regulating various cell functions such as migration, apoptosis, differentiation, and proliferation which are cell-type dependent [7–9] Because the ROCK pathway is involved in a variety of diseases, ROCK inhibitors have been developed as therapeutic drugs for endothelial dysfunction [10] 14.4 In Vitro Studies with Monoclonal Endothelial Cells (MCECs) Okumura et al immunostained MCECs for the cell cycle population marker Ki67 [11] MCECs cultured with Y-27632 showed the presence of a larger number of Ki67-positive cells compared with the controls Quantitative flow cytometric analysis revealed an increased number of Ki67-positive cells in MCECs cultured with Y-27632 Additionally, BrdU-labelling assays were conducted to confirm the effect of Y- 27632 on cell proliferation They revealed a significantly greater number of BrdU-positive MCECs among the Y-27632-treated cells compared with the control cells This demonstrated that Y-27632 plays a central role in the proliferation of MCECs In the same study, MCECs were cultured to confluence over a 14-day period and were scraped with a plastic pipette tip to create linear defect sites, and the culture was then continued for a further 24 h in fresh medium with or without 10 mM Y-27632 The mean wound distance was noted to be significantly shorter in the Y-27632 group than in the control group [11] These findings suggested that Y-27632 promoted wound healing in the in vitro model A study by Pipparelli et al showed that the selective ROCK inhibitor Y-27632 has no effect on human corneal endothelial cells proliferative capacities, but alters cellular behaviours [10] It induces changes in cell shape, increases cell adhesion, and enhances wound healing ex vivo and in vitro Its absence of toxicity, as demonstrated herein, is relevant for its use in human therapy [10] 14.5 In Vivo Rhokinase Inhibitors In an in vivo animal experiment, a corneal endothelial wound was initially made, then 10 mM Y-27632 was applied topically six times daily in the form of eye drops over a 2-day period in rabbits [11] Slit-lamp microscopic examination showed that corneal transparency and corneal thickness recovered faster in the Y-27632 group compared to the control group Ultrasound pachymetry revealed that the corneal thickness was significantly thinner in the Y-27632 group compared to the control 220 D.A Kumar group after 48 h of treatment Rabbits were then euthanized, and the wound area of the corneal endothelium was evaluated by Alizarin red staining following enucleation after 48 h The mean wound area of the Y-27632 group was significantly smaller than that of the control group These results demonstrated that the topical administration of Y-27632 eye drops enhances endothelial wound healing [11] In an animal model, Okumura compared rhokinase inhibitors with endothelial cell injection in vivo in rabbit eyes [12] Rabbit eyes were injected with cultivated rabbit corneal epithelial cells (RCECs) with the selective ROCK inhibitor Y-27632 and those cultivated RCECs without Y-27632 A control corneal endothelial dysfunction model was also kept The eyes were assessed after 48 h Rabbit eyes injected with cultivated RCECs combined with Y-27632 recovered complete transparency of the cornea In contrast, eyes injected with cultivated RCECs without Y-27632 and control eyes exhibited a hazy cornea with severe oedema Injection of cultured MCECs with a ROCK inhibitor regenerated healthy corneal endothelium and recovered corneal transparency in the monkey model, similar to the findings in the rabbit model [12] The first human clinical trial has now been initiated 14.6 Human Trials Koizumi et al reported the effect of rhokinase inhibitor in human eye in a patient with Fuchs’ corneal dystrophy [13] The patient was treated by a corneal endothelial denudation in the prepupillary region followed by the topical administration of a selective ROCK inhibitor, Y-27632, as eye drops for week (50 mL of 10 mM ROCK inhibitor, Y-27632, was applied topically as eye drops, repeated six times daily for days) and followed up for 24 months Corneal clarity was noted to improve after weeks of treatment and endothelial function was observed to sustain for 24 months In a trial by Okumura et al., the effect of Y-27632 eye drops after transcorneal freezing was evaluated in eight corneal endothelial dysfunction patients: four central corneal oedema patients and four diffuse corneal oedema patients [14] The clinical study showed that Y-27632 eye drops effectively improved corneal oedema of corneal endothelial dysfunction patients with central oedema 14.7 Conclusion Although corneal transplantations provide considerable clinical benefits, graft rejection, primary graft failure, and the shortage of donor corneas are problems that still need to be overcome Rhokinase inhibitors are in the early stage of its functional assessment in human eyes, and reports exhibit that ROCK inhibitor converts corneal endothelial cells into a phenotype capable of regenerating in vivo endothelial tissue [15] Further investigations are necessary; the topical instillation of the ROCK inhibitor might be a clinically applicable and a less invasive therapeutic modality for the treatment of corneal endothelial dysfunction in future 14 Rhokinase Inhibitors for Endothelial Decompensation 221 References Wulle KG Electron microscopy of the fetal development of the corneal endothelium and Descemet’s membrane of the human eye Invest Ophthalmol 1972;11:897–904 Olson MF, Ashworth A, Hall A An essential role for Rho, Rac, and Cdc42 GTPases in cell cycle progression through G1 Science 1995;269:1270–2 Olson MF Applications for ROCK kinase inhibition Curr Opin Cell Biol 2008;20:242–8 Narumiya S, Ishizaki T, Uehata M Use and properties of ROCK-specific inhibitor Y-27632 Methods Enzymol 2000;325:273–84 Okumura N, Ueno M, Koizumi N, Sakamoto Y, Hirata K, et al Enhancement on primate corneal endothelial cell survival in vitro by a ROCK inhibitor Invest Ophthalmol Vis Sci 2009;50:3680–7 Okumura N, Nakano S, Kay EP, et al Involvement of cyclin D and p27 in cell proliferation mediated by ROCK inhibitors Y-27632 and Y-39983 during corneal endothelium wound healing Invest Ophthalmol Vis Sci 2014;55:318–29 Yoshizaki H, Ohba Y, Parrini MC, et al Cell type-specific regulation of RhoA activity during cytokinesis J Biol Chem 2004;279:44756–62 Coleman ML, Olson MF Rho GTPase signalling pathways in the morphological changes associated with apoptosis Cell Death Differ 2002;9:493–504 Liao JK, Seto M, Noma K Rho kinase (ROCK) inhibitors J Cardiovasc Pharmacol 2007;50:17–24 10 Pipparelli A, Arsenijevic Y, Thuret G, Gain P, Nicolas M, Majo F ROCK inhibitor enhances adhesion and wound healing of human corneal endothelial cells PLoS One 2013;8(4):e62095 11 Okumura N, Koizumi N, Ueno M, Sakamoto Y, Takahashi H, Hamuro J, Kinoshita S The new therapeutic concept of using a rho kinase inhibitor for the treatment of cornealendothelial dysfunction Cornea 2011;30 Suppl 1:S54–9 12 Okumura N, Kinoshita S, Koizumi N Cell-based approach for treatment of corneal endothelial dysfunction Cornea 2014;33 Suppl 11:S37–41 13 Koizumi N, Okumura N, Ueno M, Nakagawa H, Hamuro J, Kinoshita S Rho-associated kinase inhibitor eye drop treatment as a possible medical treatment for Fuchs corneal dystrophy Cornea 2013;32(8):1167–70 14 Okumura N, Koizumi N, Kay EP, Ueno M, Sakamoto Y, Nakamura S, Hamuro J, Kinoshita S The ROCK inhibitor eye drop accelerates corneal endothelium wound healing Invest Ophthalmol Vis Sci 2013;54(4):2493–502 15 Okumura N, Koizumi N, Ueno M, et al ROCK inhibitor converts corneal endothelial cells into a phenotype capable of regenerating in vivo endothelial tissue Am J Pathol 2012;181:268–77 ... Hospitals Chennai India ISBN 978-81- 322 -28 19-6 ISBN 978-81- 322 -28 21-9 DOI 10.1007/978-81- 322 -28 21-9 (eBook) Library of Congress Control Number: 20 16945973 © Springer India 20 16 This work is subject to... 20 14; 121 :445–53 25 Melles GR Posterior lamellar keratoplasty: DLEK to DSEK to DMEK Cornea 20 06 ;25 :879–81 26 Gorovoy MS Descemet-stripping automated endothelial keratoplasty Cornea 20 06 ;25 :886–9 27 ... MO, Tan DT, et al Endothelial keratoplasty: a revolution in evolution Surv Ophthalmol 20 12; 57 :23 6– 52 Bahar I, Kaiserman I, McAllum P, et al Comparison of posterior lamellar keratoplasty techniques