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Abstract
PURPOSE To enumerate the various diagnostic modalities used for keratoconus and their evolution over the past century. METHODS A comprehensive literature search including articles on diagnosis on keratoconus were searched on PUBMED and summarized in this review. RESULTS Initially diagnosed in later stages of the disease process through clinical signs and retinoscopy, the initial introduction of corneal topography devices like Placido disc, photokeratoscopy, keratometry and computer-assisted videokeratography helped in the earlier detection of keratoconus. The evolution of corneal tomography, initially with slit scanning devices and later with Scheimpflug imaging, has vastly improved the accuracy and detection of clinical and sub-clinical disease. Analyzing the alteration in corneal biomechanics further contributed to the earlier detection of keratoconus even before the tomographic changes became evident. Anterior segment optical coherence tomography has proven to be a helpful adjuvant in diagnosing keratoconus, especially with epithelial thickness mapping. Confocal microscopy has helped us understand the alterations at a cellular level in keratoconic corneas. CONCLUSION Thus, the collective contribution of the various investigative modalities have greatly enhanced earlier and accurate detection of keratoconus, thus reducing the disease morbidity.
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Affiliation(s)
- Akhil Bevara
- Department of Cornea and Anterior segment, Cornea Institute, L V Prasad Eye Institute, Hyderabad, India
| | - Pravin K Vaddavalli
- Department of Cornea and Anterior segment, Cornea Institute, L V Prasad Eye Institute, Hyderabad, India
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Vinas-Pena M, Feng X, Li GY, Yun SH. In situ measurement of the stiffness increase in the posterior sclera after UV-riboflavin crosslinking by optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2022; 13:5434-5446. [PMID: 36425630 PMCID: PMC9664890 DOI: 10.1364/boe.463600] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 06/16/2023]
Abstract
Scleral crosslinking may provide a way to prevent or treat myopia by stiffening scleral tissues. The ability to measure the stiffness of scleral tissues in situ pre and post scleral crosslinking would be useful but has not been established. Here, we tested the feasibility of optical coherence elastography (OCE) to measure shear modulus of scleral tissues and evaluate the impact of crosslinking on different posterior scleral regions using ex vivo porcine eyes as a model. From measured elastic wave speeds at 6 - 16 kHz, we obtained out-of-plane shear modulus value of 0.71 ± 0.12 MPa (n = 20) for normal porcine scleral tissues. After riboflavin-assisted UV crosslinking, the shear modulus increased to 1.50 ± 0.39 MPa (n = 20). This 2-fold change was consistent with the increase of static Young's modulus from 5.5 ± 1.1 MPa to 9.3 ± 1.9 MPa after crosslinking, which we measured using conventional uniaxial extensometry on tissue stripes. OCE revealed regional stiffness differences across the temporal, nasal, and deeper posterior sclera. Our results show the potential of OCE as a noninvasive tool to evaluate the effect of scleral crosslinking.
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Wang D, Kuzma ML, Tan X, He TC, Dong C, Liu Z, Yang J. Phototherapy and optical waveguides for the treatment of infection. Adv Drug Deliv Rev 2021; 179:114036. [PMID: 34740763 PMCID: PMC8665112 DOI: 10.1016/j.addr.2021.114036] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 10/11/2021] [Accepted: 10/28/2021] [Indexed: 02/07/2023]
Abstract
With rapid emergence of multi-drug resistant microbes, it is imperative to seek alternative means for infection control. Optical waveguides are an auspicious delivery method for precise administration of phototherapy. Studies have shown that phototherapy is promising in fighting against a myriad of infectious pathogens (i.e. viruses, bacteria, fungi, and protozoa) including biofilm-forming species and drug-resistant strains while evading treatment resistance. When administered via optical waveguides, phototherapy can treat both superficial and deep-tissue infections while minimizing off-site effects that afflict conventional phototherapy and pharmacotherapy. Despite great therapeutic potential, exact mechanisms, materials, and fabrication designs to optimize this promising treatment option are underexplored. This review outlines principles and applications of phototherapy and optical waveguides for infection control. Research advances, challenges, and outlook regarding this delivery system are rigorously discussed in a hope to inspire future developments of optical waveguide-mediated phototherapy for the management of infection and beyond.
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Affiliation(s)
- Dingbowen Wang
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Michelle Laurel Kuzma
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xinyu Tan
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA; Academy of Orthopedics, Provincial Key Laboratory of Bone and Joint Degenerative Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong Province 510280, China
| | - Tong-Chuan He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA; Department of Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Cheng Dong
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Zhiwen Liu
- Department of Electrical Engineering, Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jian Yang
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
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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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Vandekerckhove B, Missinne J, Vonck K, Bauwens P, Verplancke R, Boon P, Raedt R, Vanfleteren J. Technological Challenges in the Development of Optogenetic Closed-Loop Therapy Approaches in Epilepsy and Related Network Disorders of the Brain. MICROMACHINES 2020; 12:38. [PMID: 33396287 PMCID: PMC7824489 DOI: 10.3390/mi12010038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/24/2020] [Accepted: 12/28/2020] [Indexed: 12/25/2022]
Abstract
Epilepsy is a chronic, neurological disorder affecting millions of people every year. The current available pharmacological and surgical treatments are lacking in overall efficacy and cause side-effects like cognitive impairment, depression, tremor, abnormal liver and kidney function. In recent years, the application of optogenetic implants have shown promise to target aberrant neuronal circuits in epilepsy with the advantage of both high spatial and temporal resolution and high cell-specificity, a feature that could tackle both the efficacy and side-effect problems in epilepsy treatment. Optrodes consist of electrodes to record local field potentials and an optical component to modulate neurons via activation of opsin expressed by these neurons. The goal of optogenetics in epilepsy is to interrupt seizure activity in its earliest state, providing a so-called closed-loop therapeutic intervention. The chronic implantation in vivo poses specific demands for the engineering of therapeutic optrodes. Enzymatic degradation and glial encapsulation of implants may compromise long-term recording and sufficient illumination of the opsin-expressing neural tissue. Engineering efforts for optimal optrode design have to be directed towards limitation of the foreign body reaction by reducing the implant's elastic modulus and overall size, while still providing stable long-term recording and large-area illumination, and guaranteeing successful intracerebral implantation. This paper presents an overview of the challenges and recent advances in the field of electrode design, neural-tissue illumination, and neural-probe implantation, with the goal of identifying a suitable candidate to be incorporated in a therapeutic approach for long-term treatment of epilepsy patients.
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Affiliation(s)
- Bram Vandekerckhove
- Center for Microsystems Technology, Imec and Ghent University, 9000 Ghent, Belgium; (B.V.); (J.M.); (P.B.); (R.V.)
| | - Jeroen Missinne
- Center for Microsystems Technology, Imec and Ghent University, 9000 Ghent, Belgium; (B.V.); (J.M.); (P.B.); (R.V.)
| | - Kristl Vonck
- 4Brain Team, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (K.V.); (P.B.); (R.R.)
| | - Pieter Bauwens
- Center for Microsystems Technology, Imec and Ghent University, 9000 Ghent, Belgium; (B.V.); (J.M.); (P.B.); (R.V.)
| | - Rik Verplancke
- Center for Microsystems Technology, Imec and Ghent University, 9000 Ghent, Belgium; (B.V.); (J.M.); (P.B.); (R.V.)
| | - Paul Boon
- 4Brain Team, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (K.V.); (P.B.); (R.R.)
| | - Robrecht Raedt
- 4Brain Team, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (K.V.); (P.B.); (R.R.)
| | - Jan Vanfleteren
- Center for Microsystems Technology, Imec and Ghent University, 9000 Ghent, Belgium; (B.V.); (J.M.); (P.B.); (R.V.)
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Feng J, Jiang Q, Rogin P, de Oliveira PW, Del Campo A. Printed Soft Optical Waveguides of PLA Copolymers for Guiding Light into Tissue. ACS APPLIED MATERIALS & INTERFACES 2020; 12:20287-20294. [PMID: 32285657 DOI: 10.1021/acsami.0c03903] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The application of optical technologies in treating pathologies and monitoring disease states requires the development of soft, minimal invasive and implantable devices to deliver light to tissues inside the body. Here, we present soft and degradable optical waveguides from poly(d,l-lactide) and derived copolymers fabricated by extrusion printing in the desired dimensions and shapes. The obtained optical waveguides propagate VIS to NIR light in air and in tissue at penetration depths of tens of centimeters. Besides, the printed waveguides have elastomeric properties at body temperature and show softness and flexibility in the range relevant for implantable devices in soft organs. Printed waveguides were able to guide light across 8 cm tissue and activate photocleavage chemical reactions in a photoresponsive hydrogel (in vitro). The simplicity and flexibility of the fiber processing method and the optical and mechanical performance of the obtained waveguides exemplify how rational study of medically approved biomaterials can lead to useful inks for printing cost-effective and flexible optical components for potential use in medical contexts.
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Affiliation(s)
- Jun Feng
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
- Chemistry Department, Saarland University, 66123 Saarbrücken, Germany
| | - Qiyang Jiang
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
- Chemistry Department, Saarland University, 66123 Saarbrücken, Germany
| | - Peter Rogin
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Peter W de Oliveira
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Aránzazu Del Campo
- INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
- Chemistry Department, Saarland University, 66123 Saarbrücken, Germany
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Salomão MQ, Hofling-Lima AL, Gomes Esporcatte LP, Lopes B, Vinciguerra R, Vinciguerra P, Bühren J, Sena N, Luz Hilgert GS, Ambrósio R. The Role of Corneal Biomechanics for the Evaluation of Ectasia Patients. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17062113. [PMID: 32209975 PMCID: PMC7143615 DOI: 10.3390/ijerph17062113] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 12/16/2022]
Abstract
Purpose: To review the role of corneal biomechanics for the clinical evaluation of patients with ectatic corneal diseases. Methods: A total of 1295 eyes were included for analysis in this study. The normal healthy group (group N) included one eye randomly selected from 736 patients with healthy corneas, the keratoconus group (group KC) included one eye randomly selected from 321 patients with keratoconus. The 113 nonoperated ectatic eyes from 125 patients with very asymmetric ectasia (group VAE-E), whose fellow eyes presented relatively normal topography (group VAE-NT), were also included. The parameters from corneal tomography and biomechanics were obtained using the Pentacam HR and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). The accuracies of the tested variables for distinguishing all cases (KC, VAE-E, and VAE-NT), for detecting clinical ectasia (KC + VAE-E) and for identifying abnormalities among the VAE-NT, were investigated. A comparison was performed considering the areas under the receiver operating characteristic curve (AUC; DeLong’s method). Results: Considering all cases (KC, VAE-E, and VAE-NT), the AUC of the tomographic-biomechanical parameter (TBI) was 0.992, which was statistically higher than all individual parameters (DeLong’s; p < 0.05): PRFI- Pentacam Random Forest Index (0.982), BAD-D- Belin -Ambrosio D value (0.959), CBI -corneal biomechanical index (0.91), and IS Abs- Inferior-superior value (0.91). The AUC of the TBI for detecting clinical ectasia (KC + VAE-E) was 0.999, and this was again statistically higher than all parameters (DeLong’s; p < 0.05): PRFI (0.996), BAD-D (0.995), CBI (0.949), and IS Abs (0.977). Considering the VAE-NT group, the AUC of the TBI was 0.966, which was also statistically higher than all parameters (DeLong’s; p < 0.05): PRFI (0.934), BAD- D (0.834), CBI (0.774), and IS Abs (0.677). Conclusions: Corneal biomechanical data enhances the evaluation of patients with corneal ectasia and meaningfully adds to the multimodal diagnostic armamentarium. The integration of biomechanical data and corneal tomography with artificial intelligence data augments the sensitivity and specificity for screening and enhancing early diagnosis. Besides, corneal biomechanics may be relevant for determining the prognosis and staging the disease.
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Affiliation(s)
- Marcella Q. Salomão
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis—BrAIN, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- Instituto Benjamin Constant, Rio de Janeiro 22290255, Brazil
| | - Ana Luisa Hofling-Lima
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
| | - Louise Pellegrino Gomes Esporcatte
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
| | - Bernardo Lopes
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- School of Engineering, University of Liverpool, L69 3GH Liverpool, UK;
| | - Riccardo Vinciguerra
- School of Engineering, University of Liverpool, L69 3GH Liverpool, UK;
- Humanitas San Pio X Hospital, 20159 Milan, Italy
| | - Paolo Vinciguerra
- The Eye Center, Humanitas Clinical and Research Center, 20089 Rozzano, Italy;
- Vincieye Clinic, 20141 Milan, Italy
| | - Jens Bühren
- Praxis für Augenheikunde Prof. Bühren, D-60431 Frankfurt, Germany;
| | - Nelson Sena
- Department of Ophthalmology, Federal University the state of Rio de Janeiro (UNIRIO), Rio de Janeiro 22290-240, Brazil;
| | | | - Renato Ambrósio
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis—BrAIN, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- Department of Ophthalmology, Federal University the state of Rio de Janeiro (UNIRIO), Rio de Janeiro 22290-240, Brazil;
- Correspondence:
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Redmond RW, Kochevar IE. Medical Applications of Rose Bengal‐ and Riboflavin‐Photosensitized Protein Crosslinking. Photochem Photobiol 2019; 95:1097-1115. [DOI: 10.1111/php.13126] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 03/27/2019] [Indexed: 01/20/2023]
Affiliation(s)
- Robert W. Redmond
- Wellman Center for Photomedicine Massachusetts General Hospital Harvard Medical School Boston MA
| | - Irene E. Kochevar
- Wellman Center for Photomedicine Massachusetts General Hospital Harvard Medical School Boston MA
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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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Wertheimer CM, Elhardt C, Kaminsky SM, Pham L, Pei Q, Mendes B, Afshar S, Kochevar IE. Enhancing Rose Bengal-Photosensitized Protein Crosslinking in the Cornea. ACTA ACUST UNITED AC 2019; 60:1845-1852. [DOI: 10.1167/iovs.19-26604] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Christian M. Wertheimer
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Carolin Elhardt
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Steffen M. Kaminsky
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Linh Pham
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Qing Pei
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Bryan Mendes
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Sepideh Afshar
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Irene E. Kochevar
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
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Silva E, Barrias P, Fuentes-Lemus E, Tirapegui C, Aspee A, Carroll L, Davies MJ, López-Alarcón C. Riboflavin-induced Type 1 photo-oxidation of tryptophan using a high intensity 365 nm light emitting diode. Free Radic Biol Med 2019; 131:133-143. [PMID: 30502456 DOI: 10.1016/j.freeradbiomed.2018.11.026] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/03/2018] [Accepted: 11/21/2018] [Indexed: 10/27/2022]
Abstract
The mechanism of photo-oxidation of tryptophan (Trp) sensitized by riboflavin (RF) was examined employing high concentrations of Trp and RF, with a high intensity 365 nm light emitting diode (LED) source under N2, 20% and 100% O2 atmospheres. Dimerization of Trp was a major pathway under the N2 atmosphere, though this occurred with a low yield (DφTrp = 5.9 × 10-3), probably as a result of extensive back electron transfer reactions between RF•- and Trp(H)•+. The presence of O2 decreased the extent of this back electron transfer reaction, and the extent of Trp dimerization. This difference is attributed to the formation of O2•- (generated via electron transfer from RF•- to O2) which reacts rapidly with Trp• leading to extensive consumption of the parent amino acid and formation of peroxides and multiple other oxygenated products (N-formylkynurenine, alcohols, diols) of Trp, as detected by LC-MS. Thus, it appears that the first step of the Type 1 mechanism of Trp photo-oxidation, induced by this high intensity 365 nm light source, is an electron transfer reaction between the amino acid and 3RF, with the presence of O2 modulating the subsequent reactions and the products formed, as a result of O2•- formation. These data have potential biological significance as LED systems and RF-based treatments have been proposed for the treatment of pathological myopia and keratitis.
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Affiliation(s)
- Eduardo Silva
- Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Química Física, Santiago, Chile.
| | - Pablo Barrias
- Universidad de Santiago de Chile, Facultad de Química y Biología, Departamento de Ciencias de los Materiales, Santiago, Chile
| | - Eduardo Fuentes-Lemus
- Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Química Física, Santiago, Chile
| | - Cristian Tirapegui
- Universidad de Santiago de Chile, Facultad de Química y Biología, Departamento de Ciencias de los Materiales, Santiago, Chile
| | - Alexis Aspee
- Universidad de Santiago de Chile, Facultad de Química y Biología, Departamento de Ciencias de los Materiales, Santiago, Chile
| | - Luke Carroll
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Michael J Davies
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Camilo López-Alarcón
- Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Química Física, Santiago, Chile.
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12
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Biocompatible and Implantable Optical Fibers and Waveguides for Biomedicine. MATERIALS 2018; 11:ma11081283. [PMID: 30044416 PMCID: PMC6117721 DOI: 10.3390/ma11081283] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 11/17/2022]
Abstract
Optical fibers and waveguides in general effectively control and modulate light propagation, and these tools have been extensively used in communication, lighting and sensing. Recently, they have received increasing attention in biomedical applications. By delivering light into deep tissue via these devices, novel applications including biological sensing, stimulation and therapy can be realized. Therefore, implantable fibers and waveguides in biocompatible formats with versatile functionalities are highly desirable. In this review, we provide an overview of recent progress in the exploration of advanced optical fibers and waveguides for biomedical applications. Specifically, we highlight novel materials design and fabrication strategies to form implantable fibers and waveguides. Furthermore, their applications in various biomedical fields such as light therapy, optogenetics, fluorescence sensing and imaging are discussed. We believe that these newly developed fiber and waveguide based devices play a crucial role in advanced optical biointerfaces.
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Abstract
PURPOSE OF REVIEW Assessment of corneal biomechanics has been an unmet clinical need in ophthalmology for many years. Many researchers and clinicians have identified corneal biomechanics as source of variability in refractive procedures and one of the main factors in keratoconus. However, it has been difficult to accurately characterize corneal biomechanics in patients. The recent development of Brillouin light scattering microscopy heightens the promise of bringing biomechanics into the clinic. The aim of this review is to overview the progress and discuss prospective applications of this new technology. RECENT FINDINGS Brillouin microscopy uses a low-power near-infrared laser beam to determine longitudinal modulus or mechanical compressibility of tissue by analyzing the return signal spectrum. Human clinical studies have demonstrated significant difference in the elastic properties of normal corneas versus corneas diagnosed with mild and severe keratoconus. Clinical data have also shown biomechanical changes after corneal cross-linking treatment of keratoconus patients. Brillouin measurements of the crystalline lens and sclera have also been demonstrated. SUMMARY Brillouin microscopy is a promising technology under commercial development at present. The technique enables physicians to characterize the biomechanical properties of ocular tissues.
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Affiliation(s)
- Seok Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital
| | - Dimitri Chernyak
- Intelon Optics Inc., Zero Emerson Place, Boston Massachusetts, USA
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Shabahang S, Kim S, Yun SH. Light-Guiding Biomaterials for Biomedical Applications. ADVANCED FUNCTIONAL MATERIALS 2018; 28:1706635. [PMID: 31435205 PMCID: PMC6703841 DOI: 10.1002/adfm.201706635] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Indexed: 05/20/2023]
Abstract
Optical techniques used in medical diagnosis, surgery, and therapy require efficient and flexible delivery of light from light sources to target tissues. While this need is currently fulfilled by glass and plastic optical fibers, recent emergence of biointegrated approaches, such as optogenetics and implanted devices, call for novel waveguides with certain biophysical and biocompatible properties and desirable shapes beyond what the conventional optical fibers can offer. To this end, exploratory efforts have begun to harness various transparent biomaterials to develop waveguides that can serve existing applications better and enable new applications in future photomedicine. Here, we review the recent progress in this new area of research for developing biomaterial-based optical waveguides. We begin with a survey of biological light-guiding structures found in plants and animals, a source of inspiration for biomaterial photonics engineering. We describe natural and synthetic polymers and hydrogels that offer appropriate optical properties, biocompatibility, biodegradability, and mechanical flexibility have been exploited for light-guiding applications. Finally, we briefly discuss perspectives on biomedical applications that may benefit from the unique properties and functionalities of light-guiding biomaterials.
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Affiliation(s)
- Soroush Shabahang
- Wellman Center for Photomedicine, Massachusetts General Hospital,
Department of Dermatology, Harvard Medical School. 65 Landsdowne Street,
Cambridge, MA 02139, USA
| | - Seonghoon Kim
- Wellman Center for Photomedicine, Massachusetts General Hospital,
Department of Dermatology, Harvard Medical School. 65 Landsdowne Street,
Cambridge, MA 02139, USA
| | - Seok-Hyun Yun
- Wellman Center for Photomedicine, Massachusetts General Hospital,
Department of Dermatology, Harvard Medical School. 65 Landsdowne Street,
Cambridge, MA 02139, USA
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Abstract
Corneal collagen cross-linking has become the preferred modality of treatment for corneal ectasia since its inception in late 1990s. Numerous studies have demonstrated the safety and efficacy of the conventional protocol. Our understanding of the cross-linking process is ever evolving, with its wide implications in the form of accelerated and pulsed protocols. Newer advancements in technology include various riboflavin formulations and the ability to deliver higher fluence protocols with customised irradiation patterns. A greater degree of customisation is likely the path forward, which will aim at achieving refractive improvements along with disease stability. The use of cross-linking for myopic correction is another avenue under exploration. Combination of half fluence cross-linking with refractive correction for high errors to prevent post LASIK regression is gaining interest. This review aims to highlight the various advancements in the cross-linking technology and its clinical applications.
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Raff AB, Seiler TG, Apiou-Sbirlea G. Bridging medicine and biomedical technology: enhance translation of fundamental research to patient care. BIOMEDICAL OPTICS EXPRESS 2017; 8:5368-5373. [PMID: 29296473 PMCID: PMC5745088 DOI: 10.1364/boe.8.005368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/19/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
The 'Bridging medicine and biomedical technology' special all-congress session took place for the first time at the OSA Biophotonics Congress: Optics in Life Sciences in 2017 (http://www.osa.org/enus/meetings/osa_meetings/optics_in_the_life_sciences/bridging_medicine_and_biomedical_technology_specia/). The purpose was to identify key challenges the biomedical scientists in academia have to overcome to translate their discoveries into clinical practice through robust collaborations with industry and discuss best practices to facilitate and accelerate the process. Our paper is intended to complement the session by providing a deeper insight into the concept behind the structure and the content we developed.
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Affiliation(s)
- Adam B. Raff
- Wellman Center for Photomedicine, Massachusetts General Hospital Research Institute and Harvard Medical School, 40 Blossom Street, Boston, MA 02114, USA
| | - Theo G. Seiler
- Wellman Center for Photomedicine, Massachusetts General Hospital Research Institute and Harvard Medical School, 40 Blossom Street, Boston, MA 02114, USA
- Department of Ophthalmology, Inselspital, University of Bern, Freiburgstrasse, CH-3010, Bern, Switzerland
| | - Gabriela Apiou-Sbirlea
- Wellman Center for Photomedicine, Massachusetts General Hospital Research Institute and Harvard Medical School, 40 Blossom Street, Boston, MA 02114, USA
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