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Mo LJ, Wang HM, Zhou HM, Huang L, Gui YX, Li QS. Collagen changes in rabbit conjunctiva after conjunctival crosslinking. Open Life Sci 2023; 18:20220604. [PMID: 37250838 PMCID: PMC10224626 DOI: 10.1515/biol-2022-0604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 02/15/2023] [Accepted: 03/27/2023] [Indexed: 05/31/2023] Open
Abstract
This study aims to determine the ultrastructural changes in collagen fibrils in rabbit conjunctiva after conjunctival crosslinking using riboflavin and ultraviolet A (UVA) light at an irradiation intensity of 45 mW/cm2. Conjunctival crosslinking may increase conjunctival stiffness. The supertemporal quadrants of the right eyes of 24 adult rabbits were treated with a topical riboflavin solution (0.25%) before irradiation with UVA light at 45 mW/cm2 for 4 min. After 3 weeks, the collagen fibrils in fibril bundles were examined by electron microscopy. Immunohistochemical staining was used to detect the expression levels of collagen I and collagen III in the rabbits' conjunctiva. The diameter of the collagen fibrils in the fibril bundles varied slightly, ranging from 30 to 60 nm in the conjunctival stroma of the control group. In the treatment group, the diameter of collagen fibrils ranged from 60 to 90 nm. The thickest collagen fibrils were observed in the treatment group (up to 90 nm in diameter). In contrast, those in the conjunctival stroma of the control group were considerably smaller (up to 60 nm in diameter). However, thicknesses of collagen fibrils displayed a unimodal distribution. Both collagen I and collagen III increased after treatment with riboflavin and UVA light irradiation at 45 mW/cm2. The data indicate that in rabbits, conjunctival crosslinking with riboflavin and UVA light at 45 mW/cm2 for 4 min is safe and does not induce ultrastructural alterations of the conjunctival cells. The conjunctival crosslinking with riboflavin and UVA light at 45 mW/cm2 can increase the diameter of collagen fibrils, but the average densities of collagen I and collagen III have no statistical significance.
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Affiliation(s)
- Li-Juan Mo
- Department of Ophthalmology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, No. 164 Lanxi Road, Putuo District, Shanghai200062, China
| | - Han-Min Wang
- Department of Ophthalmology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, No. 164 Lanxi Road, Putuo District, Shanghai200062, China
| | - Huan-Ming Zhou
- Department of Ophthalmology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, No. 164 Lanxi Road, Putuo District, Shanghai200062, China
| | - Li Huang
- Department of Gerontology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yan-Xiang Gui
- Department of Gerontology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Qing-Song Li
- Department of Ophthalmology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, No. 164 Lanxi Road, Putuo District, Shanghai200062, China
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Lai L, Lv X, Wu X, Xu Y, Chen Z, Li Y, Sun M, Zhang F. Comparing the Differences in Slowing Myopia Progression by Riboflavin/Ultraviolet A Scleral Cross-linking before and after Lens-induced Myopia in Guinea Pigs. Curr Eye Res 2021; 47:531-539. [PMID: 34935578 DOI: 10.1080/02713683.2021.2011324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE To compare the effectiveness and differences in slowing myopia progression in Guinea pigs by riboflavin/ultraviolet A (UVA) scleral cross-linking (sCXL) before and after lens-induced myopia (LIM). METHODS Forty 4-week-old Guinea pigs were randomly divided into four groups (n = 10 per group): CXL-A, CXL-B, LIM, and Control groups. The right eyes in CXL-A, CXL-B, LIM groups were treated with -10.00 D lenses from 4 to 10-week old and the left eyes were untreated. In CXL-A and CXL-B groups, riboflavin/UVA sCXL was performed on the right eyes at 4 weeks and 8 weeks of age, respectively. Both eyes were untreated in Control group. The intraocular pressure (IOP), the axial length (AXL), and the refraction were measured in vivo at 4, 8, and 10 weeks of age. At 10 weeks of age, the right eyes were enucleated for the tensile test and transmission electron microscopy observations. RESULTS The myopia has been successfully induced in LIM and CXL-B groups during 4-8 weeks. In CXL-A group, the growth rate of AXL and myopic refraction was markedly inhibited during 4-8 weeks and the inhibitory effects diminished during 8-10 weeks. During 8-10 weeks, the growth rate of AXL and myopic refraction in CXL-B were marked suppressed. At 10 weeks of age, the myopia refraction was lower and the AXL was shorter in CXL-A group in comparison to CXL-B group. The IOP was not significantly different among the 4 groups of eyes at 4, 8, and 10 weeks of age. The scleral stiffness, the fibril diameters, and the fibril density of the sclera were significantly increased in CXL-A and CXL-B groups compared to LIM group. CONCLUSION Riboflavin/UVA sCXL administrated before and after the myopia modeling could both slow the myopia progression in Guinea pigs. The before-myopia preventative sCXL showed lower myopic refraction in the same age comparison between the cross-linked groups. The effect of riboflavin/UVA sCXL might reduce over time and the long-term effect should be further investigated. This sCXL intervention might control the ultrastructure alterations of the sclera during the myopia remodeling.
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Affiliation(s)
- Lingbo Lai
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Xiaotong Lv
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Xiaowei Wu
- Beijing Stomatological Hospital, Capital Medical University School of Stomatology, Beijing, China
| | - Yushan Xu
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Zhe Chen
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Yu Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Mingshen Sun
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
| | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, China
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Wang M, Corpuz CCC, Zhang F. Shaping Eyeballs by Scleral Collagen Cross-Linking: A Hypothesis for Myopia Treatment. Front Med (Lausanne) 2021; 8:655822. [PMID: 34277654 PMCID: PMC8282923 DOI: 10.3389/fmed.2021.655822] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
The global prevalence of myopia has brought to the attention of the different eye and vision specialists, who make way to control its progression. Evidence have shown that a proactive reshaping of the eyeball is the core point of myopia developing process, which particularly includes the weakening, thinning, and expanding of the sclera. Thus, the sclera is considered to be a prime target for therapeutic manipulation in halting progressive myopia. In the past decades, corneal collagen cross-linking has been applied in clinical practice for treating aberrant corneal remodeling diseases. In this article, we hypothesize that scleral collagen cross-linking (SXL) has a huge potential in stabilizing myopic process by shaping the eyeball and preventing the aberrant scleral remodeling. In contrast with the current methods of optometry correction, such as physiotherapy, pharmacotherapy, spectacles, contact lenses, refractive surgeries, etc., eyeball-shaping method using SXL is a fundamental intervention which aims at the pathogenesis of progressive visual loss of myopia. Compared with the current posterior scleral reinforcement, the most advantage of SXL is that there is no allotransplant into the myopic eye, which means less expenditure, lower risk, and easier to handle in operating.
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Affiliation(s)
- Mengmeng Wang
- Hebei Ophthalmology Key Lab, Hebei Eye Hospital, Xingtai, China
| | | | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
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Zhang F, Lai L. Advanced Research in Scleral Cross-Linking to Prevent From Progressive Myopia. Asia Pac J Ophthalmol (Phila) 2021; 10:161-166. [PMID: 33492849 DOI: 10.1097/apo.0000000000000340] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
ABSTRACT Riboflavin-ultraviolet A (UVA) collagen cross-linking (CXL) has been applied in clinical settings to prevent the progression of keratoconus and corneal dilatation caused by other reasons in past decades. As CXL with riboflavin-UVA can enhance the stiffness of collagen-rich tissues, this technique has been further used on sclera to investigate as a safe and effective myopia prevention treatment. Despite the riboflavin-UVA scleral CXL is still in the animal and in vitro experimental phases and the mechanism is not very clear, it is promising to control myopia development clinically. In this article, researches on the laboratory experiments of riboflavin-UVA scleral CXL on scheme exploration and mechanism were reviewed in order to provide more laboratory evidence for scleral CXL in clinical myopia prevention and control in the future.
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Affiliation(s)
- Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Lab, Beijing 100730, China
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Guo P, Miao Y, Jing Y, Akella S, Wang F, Park CY, Zhang C, Chuck RS. Changes in Collagen Structure and Permeability of Rat and Human Sclera After Crosslinking. Transl Vis Sci Technol 2020; 9:45. [PMID: 32934895 PMCID: PMC7463178 DOI: 10.1167/tvst.9.9.45] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 07/11/2020] [Indexed: 11/25/2022] Open
Abstract
Purpose To use second harmonic generation imaging and fluorescence recovery after photobleaching to demonstrate alterations in scleral collagen structure and permeability after crosslinking in rat and human eyes. Methods Excised rat and human scleras were imaged ex vivo with an inverted two-photon excitation fluorescence microscope before and after photochemical crosslinking using riboflavin and 405-nm laser light. Fluorescence recovery after photobleaching was applied to measure the diffusion of fluorescein isothiocyanate–dextran across the sclera. Results Crosslinking caused scleral collagen fibers to become wavier and more densely packed, with surface collagen being more affected than deeper collagen fibers. Crosslinked sclera showed significantly decreased permeability in the irradiation zone and also extended as far as 250 µm outside the irradiation zone. Conclusions Photochemical crosslinking induced changes in scleral structure and permeability that extended to tissue even outside the irradiation zone. Translational Relevance Ultrastructural changes associated with the emerging clinical technique of photochemical scleral crosslinking have not been well characterized. We demonstrate not only changes in scleral collagen by second harmonic generation imaging but also the associated functional changes in tissue permeability by fluorescence recovery after photobleaching. We report the novel finding of reduced permeability extending well beyond the direct irradiation zone. This has implications for control in the clinical setting.
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Affiliation(s)
- Peng Guo
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA.,Analytical Imaging Facility, Albert Einstein College of Medicine, Bronx, NY, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yuan Miao
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA.,Aier School of Ophthalmology, Central South University, China
| | - Yang Jing
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
| | - Sruti Akella
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
| | - Fang Wang
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
| | - Choul Yong Park
- Department of Ophthalmology, Dongguk University Ilsan Hospital, Goyang, South Korea
| | - Cheng Zhang
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
| | - Roy S Chuck
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA
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Kwok SJJ, Forward S, Wertheimer CM, Liapis AC, Lin HH, Kim M, Seiler TG, Birngruber R, Kochevar IE, Seiler T, Yun SH. Selective Equatorial Sclera Crosslinking in the Orbit Using a Metal-Coated Polymer Waveguide. Invest Ophthalmol Vis Sci 2019; 60:2563-2570. [PMID: 31212308 PMCID: PMC6586079 DOI: 10.1167/iovs.19-26709] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/15/2019] [Indexed: 12/03/2022] Open
Abstract
Purpose Photochemical crosslinking of the sclera is an emerging technique that may prevent excessive eye elongation in pathologic myopia by stiffening the scleral tissue. To overcome the challenge of uniform light delivery in an anatomically restricted space, we previously introduced the use of flexible polymer waveguides. We presently demonstrate advanced waveguides that are optimized to deliver light selectively to equatorial sclera in the intact orbit. Methods Our waveguides consist of a polydimethylsiloxane cladding and a polyurethane core, coupled to an optical fiber. A reflective silver coating deposited on the top and side surfaces of the waveguide prevents light leakage to nontarget, periorbital tissue. Postmortem rabbits were used to test the feasibility of in situ equatorial sclera crosslinking. Tensometry measurements were performed on ex vivo rabbit eyes to confirm a biomechanical stiffening effect. Results Metal-coated waveguides enabled efficient light delivery to the entire circumference of the equatorial sclera with minimal light leakage to the periorbital tissues. Blue light was delivered to the intact orbit with a coefficient of variation in intensity of 22%, resulting in a 45 ± 11% bleaching of riboflavin fluorescence. A 2-fold increase in the Young's modulus at 5% strain (increase of 92% P < 0.05, at 25 J/cm2) was achieved for ex vivo crosslinked eyes. Conclusions Flexible polymer waveguides with reflective, biocompatible surfaces are useful for sclera crosslinking to achieve targeted light delivery. We anticipate that our demonstrated procedure will be applicable to sclera crosslinking in live animal models and, potentially, humans in vivo.
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Affiliation(s)
- Sheldon J. J. Kwok
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
- Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
| | - Sarah Forward
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Christian M. Wertheimer
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Andreas C. Liapis
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Harvey H. Lin
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Moonseok Kim
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo G. Seiler
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
- Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
- Universitätsklinik für Augenheilkunde, Inselspital, Universität Bern, Bern, Switzerland
| | - Reginald Birngruber
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
- Institut für Biomedizinische Optik, Universität zu Lübeck, Lübeck, Germany
| | - Irene E. Kochevar
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo Seiler
- Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
| | - Seok-Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
- Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
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Effects of scleral collagen crosslinking with different carbohydrate on chemical bond and ultrastructure of rabbit sclera: Future treatment for myopia progression. PLoS One 2019; 14:e0216425. [PMID: 31083660 PMCID: PMC6513270 DOI: 10.1371/journal.pone.0216425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 04/19/2019] [Indexed: 12/05/2022] Open
Abstract
Background Myopia is the most common ocular disorder and is mainly caused by axial elongation of the sclera. If the stiffness of sclera increased, it can inhibit myopia progression. The aim of this study is to compare the effect of the collagen crosslinking with different types and concentrations of carbohydrates on chemical bond and ultrastructural change of rabbit sclera. Methods Nine New Zealand white rabbits were treated with five, sequential sub-Tenon injections of 0.15 mL solutions of ribose, sucrose, and glycogen of 0.1, 0.2 and 0.4 M concentration at the right eye over 14 days. Ten weeks after the last injection, the rabbits were sacrificed and chemical bond and ultrastructural changes were compared with those of the untreated left sclera using Raman spectroscopy, atomic force microscopy (AFM), and histology. Results Raman spectroscopy of the control and cross-linked rabbit sclera tissue revealed different types of collagen interactions. Raman shift of 919 cm-1 (C-C stretching and vibration of the proline ring in collagen) was the highest in ribose, followed by sucrose and glycogen. Total energy intensity was also highest in ribose, followed by sucrose and glycogen, and showed a tendency to increase at higher concentrations. AFM revealed interlocking arrangements of collagen fibrils. The collagen fibril diameter was 105.6 ± 21.2 nm, 109.4 ± 28.8 nm, 113.1 ± 30.8 nm and 137.6 ± 25.3 nm for control group, 0.4 M glycogen, sucrose, and ribose, respectively. Histology indicated increased density of the collagen bundle and no increase in inflammatory cell recruitment compared to control at high concentrations of ribose. Conclusions Scleral crosslinking using glycation increased the scleral biomechanical rigidity and these results were particularly pronounced in ribose. Scleral crosslinking using glycation may be a promising method for inhibiting high myopia progression.
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Ocular safety evaluation of blue light scleral cross-linking in vivo in rhesus macaques. Graefes Arch Clin Exp Ophthalmol 2019; 257:1435-1442. [PMID: 31065848 DOI: 10.1007/s00417-019-04346-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 03/11/2019] [Accepted: 04/22/2019] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To investigate the safety of blue light scleral cross-linking (SXL) by evaluating changes in biological parameters in the retina and choroid in the eyes of rhesus macaques (Macaca mulatta). METHODS Fifteen 3-year-old macaques (30 eyes) were randomly divided into three groups (n = 5). SXL was performed via riboflavin (0.5%) and blue light (460 nm) at the location of the equatorial sclera. Right eyes served as experimental eyes, and left eyes as control eyes. One quadrant of each right eye was irradiated in group A, two quadrants of each right eye and one quadrant of each left eye were irradiated in group B, and two quadrants of each right eye were irradiated in group C. Optical coherence tomography, optical coherence tomography angiography, and flash electroretinography (f-ERG) examinations were performed at baseline and 1 week, 1 month, 3 months, and 6 months after SXL. Additionally, retinal tissue alterations were detected via transmission electron microscopy at 1 week postoperatively. RESULTS There were no significant differences between experimental eyes and control eyes in retinal thickness, vessel density of retinal superficial capillary plexus, and choroid thickness in any of the groups at any of the time points investigated (p > 0.05). Significant reductions in f-ERG parameters were detected 1 week postoperatively in the experimental eyes of groups A and C (p < 0.05), but they gradually recovered, and there was no significant difference 1 month postoperatively (p > 0.05). Ultrastructural changes were evident in the retinal layers of SXL eyes. In group B, there were no significant differences between the right and left eyes at any of the follow-up time points investigated. CONCLUSIONS Blue light SXL can cause transient retina damage. The f-ERG parameters reductions and retinal ultrastructural changes were found at early stage, even though there were not significant changes in retinal thickness, vessel density of retinal superficial capillary plexus, and choroid thickness after blue light SXL. The long-term intraocular safety of the blue light SXL technique should be investigated further.
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Posterior staphyloma in pathologic myopia. Prog Retin Eye Res 2018; 70:99-109. [PMID: 30537538 DOI: 10.1016/j.preteyeres.2018.12.001] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 11/24/2022]
Abstract
A posterior staphyloma is an outpouching of a circumscribed region of the posterior fundus and has been considered a hallmark of pathologic myopia. Occurring in highly myopic eyes, it is histologically characterized by a relatively abrupt scleral thinning starting at the staphyloma edge, a pronounced de-arrangement of scleral collagen fibrils and a marked choroidal thinning, which is the most marked at the staphyloma edge and which occurs in addition to the axial elongation-associated choroidal thinning. Besides in highly myopic eyes, a posterior staphyloma can be found in non-highly myopic eyes in association with retinitis pigmentosa or localized defects of Bruch's membrane in the cases of which it is not associated with a marked choroidal thinning. The diagnosis of posterior staphylomas is considered best made by wide-field optical coherence tomography, because wide-field optical coherence tomography encompasses the entire extent of the most predominant type of staphylomas (i.e., the wide macular type) and since it also has a sufficiently high resolution of images (in contrast to ultrasonography, computed tomography and three-dimensional magnetic resonance imaging). While the etiology of posterior staphylomas has remained unclear, local choroidal factors and a locally decreased biomechanical resistance of the sclera against a posteriorly expanding Bruch's membrane have been one of the assumed pathogenic parameters. For the therapy of staphylomas, scleral reinforcement strategies such as by posterior encircling bands, posterior scleral collagen cross-linking or scleral regeneration have been discussed or performed, however, with the pathogenesis being elusive, the therapy of staphylomas has remained undetermined.
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Kwok SJJ, Kim M, Lin HH, Seiler TG, Beck E, Shao P, Kochevar IE, Seiler T, Yun SH. Flexible Optical Waveguides for Uniform Periscleral Cross-Linking. Invest Ophthalmol Vis Sci 2017; 58:2596-2602. [PMID: 28494493 PMCID: PMC5433838 DOI: 10.1167/iovs.17-21559] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery. Methods Waveguides were fabricated from polydimethylsiloxane elastomer. Blue light (445 nm) is coupled into the waveguide with an input fiber. Light delivery efficiency from the waveguide to scleral tissue was measured and fit to a theoretical model. SXL was performed on fresh porcine eyes stained with 0.5% riboflavin, using irradiances of 0, 25, and 50 mW/cm2 around the entire equator of the eye. Stiffness of scleral strips was characterized with tensiometry. Results Light delivery with a waveguide of tapered thickness (1.4–0.5 mm) enhanced the uniformity of light delivery, compared to a flat waveguide, achieving a coefficient of variation of less than 10%. At 8% strain, sclera cross-linked with the waveguides at 50 mW/cm2 for 30 minutes had a Young's modulus of 10.7 ± 1.0 MPa, compared to 5.9 ± 0.5 MPa for no irradiation, with no difference in stiffness between proximally and distally treated halves. The stiffness of waveguide-irradiated samples did not differ from direct irradiation at the same irradiance. Conclusions We developed flexible waveguides for periscleral cross-linking. We demonstrated efficient and uniform stiffening of a 5-mm-wide equatorial band of scleral tissue.
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Affiliation(s)
- Sheldon J J Kwok
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 2Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
| | - Moonseok Kim
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Harvey H Lin
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo G Seiler
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 3Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
| | - Eric Beck
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Peng Shao
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Irene E Kochevar
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States
| | - Theo Seiler
- Institute for Refractive and Ophthalmic Surgery (IROC), Zurich, Switzerland
| | - Seok-Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States 2Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
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Iomdina ЕN, Tarutta ЕP, Semchishen VА, Korigodskiy АR, Zakharov ID, Khoroshilova-Maslova IP, Ignat'eva NY, Kiseleva ТN, Sianosyan АА, Milash SV. [Experimental realization of minimally invasive techniques of scleral collagen cross-linking]. Vestn Oftalmol 2017; 132:49-58. [PMID: 28121299 DOI: 10.17116/oftalma2016132649-56] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
AIM To realize two minimally invasive techniques of scleral collagen cross-linking (SXL) at the equator and posterior pole of the eye: 1) targeted irradiation of the region with ultraviolet A (UVA) and 2) sub-Tenon injection of Sklerateks. MATERIAL AND METHODS To perform UVA-SXL, a tool was developed that includes a UV-LED light source (370 nm, 3 mW/cm2) and a polymer-coated silica multimode optical fiber located in one of the two channels of a detachable metal tip. The other channel is used to deliver riboflavin to the scleral surface. The study included 8 Chinchillas' eyes. Intact fellow eyes served as the controls. Scleral echodensity was measured in vivo with Voluson 730 Pro (Kretz) prior to the procedure and then 2 days and 1 month after. After enucleation, the elastic modulus and the degree of scleral cross-linking were established at the same time-points. A placebo-controlled study on the safety and effectiveness of sub-Tenon Sklerateks injections (solution of amino acid salts in the form of succinates) was conducted on 47 Chinchilla rabbits (94 eyes). Sklerateks or placebo (0.1 ml) was injected below the Tenon's capsule of either eye once a week for 1 month (4 injections; 1st series) or 3 months (12 injections; 2nd series). After the end of the course, 22 eyes were studied morphologically. In 72 eyes, scleral samples were obtained in order to evaluate the elastic modulus (Autograph AGS-H tester, SHIMADZU, Japan) and the rate of cross-linking (judging from the denaturation temperature) by differential scanning calorimetry (Phoenix DSC 204 calorimeter, Netzsch, Germany). RESULTS After UVA irradiation, the scleral echodensity increased from 86.7±5.1 to 98±4.9 dB. The elastic modulus appeared 1.5 times higher than that of the control samples. The denaturation temperature also increased indicating the rate of scleral cross-linking as high as 15-18%. Weekly Sklerateks for 1-3 months has been shown to induce neither clinical, nor morphological signs of local irritative, damaging, or toxic effect. The findings also include: a 1.8 times higher rate of scleral cross-linking, activation of cellular elements, neoformation of connective tissue on the scleral surface, and vascular growth, which together indicate a pronounced metabolic and strengthening effect of Sklerateks on the sclera. CONCLUSION Experimental results on minimally invasive techniques of SXL allow to recommend them for further clinical investigation as a promising treatment of progressive myopia.
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Affiliation(s)
- Е N Iomdina
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - Е P Tarutta
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - V А Semchishen
- Federal Research Center 'Crystallography and photonics', Russian Academy of Sciencs, 59 Leninskiy prospekt, Moscow, 119333, Russian Federation
| | - А R Korigodskiy
- HajBiTek LLC, 44-1 Mira prospekt, Moscow, Russian Federation, 129110
| | - I D Zakharov
- HajBiTek LLC, 44-1 Mira prospekt, Moscow, Russian Federation, 129110
| | - I P Khoroshilova-Maslova
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - N Yu Ignat'eva
- Lomonosov Moscow State University, 1 Leninskie Gory, Moscow, 119991, Russian Federation
| | - Т N Kiseleva
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - А А Sianosyan
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
| | - S V Milash
- Moscow Helmholtz Research Institute of Eye Diseases, Ministry of Health of the Russian Federation, 14/19 Sadovaya-Chernogryazskaya St., Moscow, 105062, Russian Federation
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