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Sinjab MM, Rubinfeld RS, Wagner K, Parsons Jnr EC, Cummings AB, Belin MW. Outcomes of Conductive Keratoplasty Combined with Corneal Crosslinking in Advanced Ectatic Corneal Disease. Clin Ophthalmol 2021; 15:1317-1329. [PMID: 33824576 PMCID: PMC8018415 DOI: 10.2147/opth.s259012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 01/15/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose To assess the effectiveness of a novel treatment for patients with advanced corneal ectasia and loss of visual acuity (VA). Conductive keratoplasty (CK) is performed to improve VA followed by epithelium-on (epi-on) corneal crosslinking (CXL) to stabilize the cornea after CK. Methods Retrospective, exploratory cohort study. Patients with keratoconus or postsurgical ectasia and best spectacle-corrected distance VA (CDVA) ≤ 20/40 were included. Conductive keratoplasty was performed (ViewPoint CK System, Refractec, Inc., Bloomington, MN); followed a day later by epi-on CXL (CXLUSA/CXLO, Bethesda, MD/CXLO Encinitas, CA). Measures included uncorrected distance visual acuity (UDVA) and CDVA, as well as refractive and tomographic measures and tomographic indices. Results Data from 50 eyes of 45 patients were analyzed. Mean follow-up was 15.1 ± 12.2 months (range: 2 to 51). Overall, UDVA and CDVA improved postoperatively. Subjective refraction and tomographic metrics did not show consistent changes, but changes in tomographic indices were associated with treatment follow-up time. At the 1-year visit, mean UDVA significantly improved over baseline (P = 0.009) by approximately 3 lines; mean CDVA improved significantly (P = 10−5) by approximately 2 lines. No eye lost lines of CDVA. Change in the Index of Surface Variance (ISV) was associated with treatment, and the D-Index trended over follow-up time. Conclusion Conductive keratoplasty with a proprietary epi-on CXL treatment improved vision in patients with advanced ectasia This CK/epi-on CXL treatment offers the possibility of improved VA for patients with compromised vision due to ectasia.
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Affiliation(s)
- Mazen M Sinjab
- Dr. Mazen Eye Clinic, Medcare Hospitals and Centres, Dubai, United Arab Emirates.,Al Zahra Medical Group, Damascus, Syria
| | - Roy S Rubinfeld
- Department of Ophthalmology, Georgetown University Medical School/Washington Hospital Center, Washington, DC, USA.,Re:Vision Private Practice, Rockville, MD, USA
| | - Kirsten Wagner
- Department of Ophthalmology, Medstar Georgetown University Hospital, Washington, DC, USA.,Department of Ophthalmology, Medstar Washington Hospital Center, Washington, DC, USA
| | | | | | - Michael W Belin
- Department of Ophthalmology, University of Arizona, Tucson, AZ, USA
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Comparison of penetrating keratoplasty outcomes with or without microwave thermokeratoplasty. Sci Rep 2021; 11:5995. [PMID: 33727665 PMCID: PMC7966373 DOI: 10.1038/s41598-021-85470-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 02/19/2021] [Indexed: 11/08/2022] Open
Abstract
Microwave thermokeratoplasty (MTK) is a surgical procedure for the correction of pathologic corneal steepening. The purpose of this study was to examine the postoperative outcomes of eyes with advanced keratoconus that underwent femtosecond-laser zig-zag penetrating keratoplasty (z-PK) following MTK for reshaping of the central cornea. This study involved 32 eyes of 32 consecutive advanced keratoconus patients; i.e., 25 eyes of 25 patients who underwent MTK prior to z-PK (MTK + z-PK group), and 7 eyes of 7 patients who underwent z-PK alone (z-PK group). In all treated eyes, visual acuity (VA) and corneal topography were measured before surgery and at 6-months postoperative. At 6-months postoperative, the mean uncorrected distance VA (logarithm of the minimum angle of resolution) and surface regularity index (SRI) of the MTK + z-PK group was 0.62 ± 0.39 (mean ± standard deviation) and 1.26 ± 0.45, respectively, while that in the z-PK group was 1.02 ± 0.18 and 7.64 ± 3.22, respectively. Both variables were significantly better in the MTK + z-PK group than in the z-PK group (P < 0.05). The findings in this study reveal that MTK prior to z-PKP is effective for improving UDVA and reducing the irregularity of corneal topography in patients with advanced keratoconus.
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Kankariya VP, Dube AB, Grentzelos MA, Kontadakis GA, Diakonis VF, Petrelli M, Kymionis GD. Corneal cross-linking (CXL) combined with refractive surgery for the comprehensive management of keratoconus: CXL plus. Indian J Ophthalmol 2020; 68:2757-2772. [PMID: 33229651 PMCID: PMC7856931 DOI: 10.4103/ijo.ijo_1841_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The past two decades have witnessed an unprecedented evolution in the management of keratoconus that demands a holistic approach comprising of inhibiting the ectatic progression as well as visual rehabilitation. The advent of corneal cross-linking (CXL) in the late 1990s resulted in long-term stabilization of the ectatic cornea along with limited reduction in corneal steepening and regularization of corneal curvature. However, CXL as a standalone procedure does not suffice in rehabilitating the functional vision especially in patients who are unwilling or intolerant towards contact lenses. The concept of “CXL plus” was proposed which incorporates adjunctive use of refractive procedures with CXL in order to overcome the optical inefficiency due to corneal irregularity, decrease the irregular astigmatism, correct the residual refractive error and improve functional visual outcome in keratoconus. Several refractive procedures such as conductive keratoplasty (CK), photorefractive keratectomy (PRK), transepithelial phototherapeutic keratectomy (t-PTK), intrastromal corneal ring segments (ICRS) implantation, phakic intraocular lens (PIOL) implantation and multiple other techniques have been combined with CXL to optimize and enhance the CXL outcome. This review aimed to summarize the different protocols of CXL plus, provide guidelines for selection of the optimum CXL plus technique and aid in decision-making for the comprehensive management of cases with primary keratoconus in addition to discussing the future and scope for innovations in the existing treatment protocols.
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Affiliation(s)
| | - Ankita B Dube
- Asian Eye Hospital and Laser Institute, Pune, Maharashtra, India
| | - Michael A Grentzelos
- Asian Eye Hospital and Laser Institute, Pune, Maharashtra, India; Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - George A Kontadakis
- Laboratory of Vision and Optics, Medical School, University of Crete, Heraklion, Greece
| | | | - Myrsini Petrelli
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - George D Kymionis
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
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Ansah DO, Wang J, Lu K, Jabbour S, Bower KS, Soiberman US. Post-FDA Approval Results of Epithelium-Off, Full-Fluence, Dresden Protocol Corneal Collagen Crosslinking in the USA. Ophthalmol Ther 2020; 9:1023-1040. [PMID: 33029700 PMCID: PMC7708565 DOI: 10.1007/s40123-020-00306-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/16/2020] [Indexed: 12/11/2022] Open
Abstract
Introduction The purpose of this non-comparative, prospective, observational study was to evaluate the post-US Food and Drug Administration approval outcomes of epithelium-off, full-fluence, Dresden protocol corneal collagen crosslinking (CXL) for the treatment of progressive keratoconus (KCN) and post-refractive corneal ectasia at a US academic tertiary medical center. Methods This study involved 125 eyes of 97 patients with KCN and 13 eyes of 12 patients with post-refractive ectasia which underwent CXL between November 2016 and September 2019. Best spectacle-corrected visual acuity (BSCVA) and corneal topographic parameters were measured preoperatively, at postoperative month 1 (POM-1), and between postoperative months 3 and 24 (POM 3–24). Results Best spectacle-corrected visual acuity, flat keratometry, steep keratometry, and mean corneal power worsened at POM-1 (p < 0.01) with a return to preoperative values at POM 3–24. Maximum keratometry (Kmax) steepened at POM-1 and then improved beyond preoperative levels at POM 3–24 (p < 0.01 and p = 0.03, respectively). Pachymetry at the apex and pupil decreased at POM-1 and POM 3–24 (p = 0.03). Pachymetry at the thinnest point decreased at POM-1 and trended toward reduction at POM 3–24 (p < 0.001 and p = 0.06, respectively). Visual and tomographic outcomes were similar between pediatric and adult populations, and between KCN and post-refractive ectasia patients. Conclusions Real-world results of CXL in the USA are similar to those reported in prior studies, demonstrating an initial worsening of BSCVA, pachymetry, and keratometry followed by corneal flattening and preservation of visual acuity. Improvements in Kmax and stability in visual acuity were observed over 24 months in children and adults with progressive KCN or post-refractive ectasia.
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Affiliation(s)
- Derick O Ansah
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jiangxia Wang
- Department of Biostatistics, Johns Hopkins Biostatistics Center, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Kevin Lu
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Samir Jabbour
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kraig S Bower
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Uri S Soiberman
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Zhu AY, Jun AS, Soiberman US. Combined Protocols for Corneal Collagen Cross-Linking with Photorefractive Surgery for Refractive Management of Keratoconus: Update on Techniques and Review of Literature. Ophthalmol Ther 2019; 8:15-31. [PMID: 31605317 PMCID: PMC6789054 DOI: 10.1007/s40123-019-00210-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Indexed: 12/13/2022] Open
Abstract
With the development and gradual dissemination of corneal collagen cross-linking (CXL) in the twenty-first century as an early treatment for keratoconus, the management paradigm has shifted to include a greater focus on complete refractive correction for these patients. Though supplemental hard contact lens therapy remains a mainstay of visual rehabilitation in keratoconus, there has been increasing appeal in a completely surgical approach by combining CXL with adjuvant refractive procedures to both halt the ectatic process and enhance functional visual outcomes. Collectively termed "CXL plus" procedures, several combined protocols have been studied to various degrees in conjunction with CXL, involving photorefractive keratectomy (PRK), transepithelial phototherapeutic keratectomy (PTK), conductive keratoplasty (CK), intrastromal corneal ring segments (ICRS) implantation, phakic intraocular lens (PIOL) implantation, or multiple of these techniques together. The scope of this review aims to encompass a summary of current CXL protocols and present the current status of studies involving adjunctive keratorefractive procedures combined with CXL. By discussing the results to date of these CXL plus protocols, we can assess what further areas of investigation are necessary within this field as the next step to optimizing treatment modalities and outcomes for our keratoconus patients, regardless of disease severity.
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Affiliation(s)
- Angela Y Zhu
- Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Albert S Jun
- Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Uri S Soiberman
- Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
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Mohammadpour M, Heidari Z, Hashemi H. Updates on Managements for Keratoconus. J Curr Ophthalmol 2017; 30:110-124. [PMID: 29988906 PMCID: PMC6034171 DOI: 10.1016/j.joco.2017.11.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 10/07/2017] [Accepted: 11/05/2017] [Indexed: 12/26/2022] Open
Abstract
Purpose Keratoconus is a progressive disease of the cornea which can lead to blindness as irregular astigmatism increases. Currently, a variety of methods are available for the treatment of keratoconus, and in certain cases, it may be difficult to choose the most appropriate option. This article reviews available treatment modalities for keratoconus to provide the practitioner with practical and useful information for selecting the most suitable option for each individual patient. Methods To review treatment methods for different stages of keratoconus, PubMed (United States National Library of Medicine) and Scopus (Elsevier BV) databases were searched using the keywords “keratoconus”, “contact lens”, “cross-linking”, “Intacs”, “keratoplasty”, “gene therapy”, and “irregular astigmatism”, and related articles were reviewed based on disease assessment parameters and treatment methods. Results Various methods are available for the treatment of keratoconus: eyeglasses and contact lenses in the early stages, cross-linking for stabilizing disease progression, intrastromal corneal ring segments (ICRS) for reducing refractive errors or flattening the cornea, and penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK), conductive keratoplasty, gene therapy and more recently, bowman layer transplantation (BL transplantation) in advanced stages of the disease. To achieve optimum results, it is essential to choose the best option for each individual patient. Conclusions A commonality of the reviewed papers was the advancement of novel diagnostic and treatment methods in ophthalmology, which can delay the need for corneal grafting. A better understanding of keratoconus treatment options can help enhance visual rehabilitation and prevent blindness in keratoconus patients.
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Affiliation(s)
- Mehrdad Mohammadpour
- Eye Research Center, Ophthalmology Department, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Zahra Heidari
- Eye Research Center, Ophthalmology Department, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
- Corresponding author. No. 96 Esfandiar Blvd., Vali'asr Ave., Tehran, Iran.
| | - Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
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Parker JS, van Dijk K, Melles GRJ. Treatment options for advanced keratoconus: A review. Surv Ophthalmol 2015; 60:459-80. [PMID: 26077628 DOI: 10.1016/j.survophthal.2015.02.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/17/2015] [Accepted: 02/20/2015] [Indexed: 10/23/2022]
Abstract
Traditionally, the mainstay of treatment for advanced keratoconus (KC) has been either penetrating or deep anterior lamellar keratoplasty (PK or DALK, respectively). The success of both operations, however, has been somewhat tempered by potential difficulties and complications, both intraoperatively and postoperatively. These include suture and wound-healing problems, progression of disease in the recipient rim, allograft reaction, and persistent irregular astigmatism. Taken together, these have been the inspiration for an ongoing search for less troublesome therapeutic alternatives. These include ultraviolet crosslinking and intracorneal ring segments, both of which were originally constrained in their indication exclusively to eyes with mild to moderate disease. More recently, Bowman layer transplantation has been introduced for reversing corneal ectasia in eyes with advanced KC, re-enabling comfortable contact lens wear and permitting PK and DALK to be postponed or avoided entirely. We offer a summary of the current and emerging treatment options for advanced KC, aiming to provide the corneal specialist useful information in selecting the optimal therapy for individual patients.
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Affiliation(s)
- Jack S Parker
- Netherlands Institute for Innovative Ocular Surgery, Rotterdam, The Netherlands; Melles Cornea Clinic, Rotterdam, The Netherlands; UAB Callahan Eye Hospital, Birmingham, Alabama, USA
| | - Korine van Dijk
- Netherlands Institute for Innovative Ocular Surgery, Rotterdam, The Netherlands; Melles Cornea Clinic, Rotterdam, The Netherlands
| | - Gerrit R J Melles
- Netherlands Institute for Innovative Ocular Surgery, Rotterdam, The Netherlands; Melles Cornea Clinic, Rotterdam, The Netherlands; Amnitrans EyeBank, Rotterdam, The Netherlands.
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Abstract
Keratoconus is characterized by progressive corneal protrusion and thinning, leading to irregular astigmatism and impairment in visual function. The etiology and pathogenesis of the condition are not fully understood. However, significant strides have been made in early clinical detection of the disease, as well as towards providing optimal optical and surgical correction for improving the quality of vision in affected patients. The past two decades, in particular, have seen exciting new developments promising to alter the natural history of keratoconus in a favorable way for the first time. This comprehensive review focuses on analyzing the role of advanced imaging techniques in the diagnosis and treatment of keratoconus and evaluating the evidence supporting or refuting the efficacy of therapeutic advances for keratoconus, such as newer contact lens designs, collagen crosslinking, deep anterior lamellar keratoplasty, intracorneal ring segments, photorefractive keratectomy, and phakic intraocular lenses.
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Affiliation(s)
- Jayesh Vazirani
- Cornea and Anterior Segment Services, LV Prasad Eye Institute, Hyderabad, India
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9
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Barton MD, Trembly BS. Measurement of the anisotropic thermal conductivity of the porcine cornea. Exp Eye Res 2013; 115:216-23. [PMID: 23933570 DOI: 10.1016/j.exer.2013.07.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/28/2013] [Accepted: 07/29/2013] [Indexed: 11/19/2022]
Abstract
Accurate thermal models for the cornea of the eye support the development of thermal techniques for reshaping the cornea and other scientific purposes. Heat transfer in the cornea must be quantified accurately so that a thermal treatment does not destroy the endothelial layer, which cannot regenerate, and yet is responsible for maintaining corneal transparency. We developed a custom apparatus to measure the thermal conductivity of ex vivo porcine corneas perpendicular to the surface and applied a commercial apparatus to measure thermal conductivity parallel to the surface. We found that corneal thermal conductivity is 14% anisotropic at the normal state of corneal hydration. Small numbers of ex vivo feline and human corneas had a thermal conductivity perpendicular to the surface that was indistinguishable from the porcine corneas. Aqueous humor from ex vivo porcine, feline, and human eyes had a thermal conductivity nearly equal to that of water. Including the anisotropy of corneal thermal conductivity will improve the predictive power of thermal models of the eye.
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Affiliation(s)
- Michael D Barton
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA.
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Vega-Estrada A, Alió JL, Plaza Puche AB, Marshall J. Outcomes of a new microwave procedure followed by accelerated cross-linking for the treatment of keratoconus: a pilot study. J Refract Surg 2013; 28:787-93. [PMID: 23347373 DOI: 10.3928/1081597x-20121011-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 09/21/2012] [Indexed: 11/20/2022]
Abstract
PURPOSE To analyze the initial data obtained in a group of patients treated with microwave keratoplasty followed by accelerated corneal collagen cross-linking (CXL) for the correction of keratoconus. METHODS Prospective, nonrandomized clinical study including six eyes from four patients treated with microwave thermal keratoplasty followed by accelerated CXL. Refractive, topographic, anterior aberrometry, and corneal biomechanics outcomes were analyzed during 6-month follow-up. RESULTS Immediately after the procedure, a significant reduction of >7.00 diopters (D) was observed in mean keratometry (P=.02). Uncorrected distance visual acuity increased from 0.92±0.52 logMAR (Snellen 20/160) preoperatively to 0.47±0.19 logMAR (Snellen 20/60) postoperatively (P=.05). No statistically significant change was found in corrected distance visual acuity (P=.28). Corneal higher order aberration decreased from 1.89±0.90 to 1.51±0.65 μm and corneal primary coma aberration decreased from 1.45±0.68 μm preoperatively to 0.84±0.23 μm postoperatively (P>.10). No statistically significant changes were found in the biomechanics variables (P=.40). A significant regression of the effect was assessed in keratometry at the end of follow-up (P=.03). CONCLUSIONS The Keraflex procedure may have the ability to improve refractive status in patients who suffer from keratoconus, as well as induce corneal remodeling to a more anterior regular surface. However, the current treatment regimen is not sufficient to maintain the flattening effect achieved and significant regression occurs.
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Affiliation(s)
- Alfredo Vega-Estrada
- Keratoconus Unit, Vissum/Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain
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Abstract
Pre-2000, the clinical management of keratoconus centred on rigid contact lens fitting when spectacle corrected acuity was no longer adequate, and transplantation where contact lens wear failed. Over the last decade, outcome data have accumulated for new interventions including corneal collagen crosslinking, intracorneal ring implantation, topographic phototherapeutic keratectomy, and phakic intraocular lens implantation. We review the current evidence base for these interventions and their place in new management pathways for keratoconus under two key headings: corneal shape stabilisation and visual rehabilitation.
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Affiliation(s)
- D M Gore
- Moorfields Eye Hospital, London, UK.
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McAlinden C. Corneal refractive surgery: past to present. Clin Exp Optom 2012; 95:386-98. [PMID: 22672114 DOI: 10.1111/j.1444-0938.2012.00761.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 04/07/2012] [Accepted: 04/17/2012] [Indexed: 12/20/2022] Open
Abstract
There have been many historical corneal refractive techniques and procedures developed over the years. From early techniques of radial keratotomy to modern excimer laser techniques, the field of refractive surgery is one of the most rapidly developing in ophthalmology. This review details the historical aspects of the many early techniques up to current techniques used on millions of eyes around the world.
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Affiliation(s)
- Colm McAlinden
- University of Ulster, United Kingdom and Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia.
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Kanellopoulos AJ. Laboratory evaluation of selective in situ refractive cornea collagen shrinkage with continuous wave infrared laser combined with transepithelial collagen cross-linking: a novel refractive procedure. Clin Ophthalmol 2012; 6:645-52. [PMID: 22570545 PMCID: PMC3346186 DOI: 10.2147/opth.s31250] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background This research comprised a laboratory evaluation of a novel refractive surgery technique involving sequential corneal subsurface shrinkage-driven reshaping using a continuous wave mid-infrared laser application followed by stiffening via rapid transepithelial higher fluence collagen cross-linking for shape persistence/longevity on cadaver corneas. Materials and methods Ten cadaver corneas were used in this study. During use, all were affixed in an artificial chamber. Thermal delivery entailed a continuous wave laser at 2013 nm wavelength, approximately 650 mW power under scanner control (about 3 mm/sec linear draw speed), with a planoconcave sapphire applanation lens cooled to 8°C. Group 1 (n = 5, myopic treatment) eyes were exposed to three concentric annuli with diameters of 3 mm, 4 mm, and 5 mm. Group 2 (n = 5, hyperopic treatment) eyes were exposed to three concentric annuli with diameters of 6 mm, 7 mm, and 8 mm. The clinical change in shape of the cornea was visualized immediately under a slit-lamp. A transepithelial higher fluence corneal collagen cross-linking step followed each thermal treatment, comprising 0.1% riboflavin drops with 0.02% benzalkonium chloride and 0.2% carboxymethlycellulose in deuterated water (D2O) applied on the epithelium corneal surface for 10 minutes. Next, each cornea was exposed to 10 mW/cm2 of ultraviolet A (365 nm) light for 10 minutes. The corneas were evaluated before and after thermal remodeling and cornea collagen cross-linking for corneal topography, corneal optical coherence tomography, cornea Scheimpflug tomography, and clinical photographs. Results The histopathology effect was noted clinically as concentric white rings underneath the epithelium and Bowman’s membrane, with the lesion depth extending down to 400 μm in the mid stroma of the cornea. This was confirmed by corneal anterior segment optical coherence tomography. The topographic change noted was a 4–8 diopter hyperopic shift in group 1 and a 2–6 diopter myopic shift in group 2. Conclusion This novel refractive surgery technique appears to generate a significant refractive change (+/−) in the cornea, without affecting the epithelium or Bowman’s membrane and without any visible epithelial defect. The transepithelial collagen cross-linking used as a second step in the same procedure aims to stabilize this effect in the long term. Further clinical studies are planned to validate these initial clinical results.
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Corneal topographic analysis in patients with keratoconus using 3-dimensional anterior segment optical coherence tomography. J Cataract Refract Surg 2011; 37:1871-8. [PMID: 21930048 DOI: 10.1016/j.jcrs.2011.05.027] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 04/05/2011] [Accepted: 05/02/2011] [Indexed: 11/20/2022]
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Reply. Am J Ophthalmol 2011. [DOI: 10.1016/j.ajo.2011.01.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Oral D, Kaya V. Topography-guided conductive keratoplasty for keratoconus. Am J Ophthalmol 2011; 151:1102-3; author reply 1103. [PMID: 21616213 DOI: 10.1016/j.ajo.2011.01.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 01/27/2011] [Indexed: 10/18/2022]
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Basu S, Sangwan VS. Efficacy and safety of conductive keratoplasty in keratoconus. Am J Ophthalmol 2011; 151:735; author reply 735-6. [PMID: 21420528 DOI: 10.1016/j.ajo.2010.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 12/27/2010] [Indexed: 11/20/2022]
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Kato N, Tsubota K. Reply. Am J Ophthalmol 2011. [DOI: 10.1016/j.ajo.2010.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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