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Naik K, du Toit LC, Ally N, Choonara YE. In vivo evaluation of a Nano-enabled therapeutic vitreous substitute for the precise delivery of triamcinolone to the posterior segment of the eye. Drug Deliv Transl Res 2024:10.1007/s13346-024-01566-1. [PMID: 38519828 DOI: 10.1007/s13346-024-01566-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2024] [Indexed: 03/25/2024]
Abstract
This study focused on the design of a thermoresponsive, nano-enabled vitreous substitute for the treatment of retinal diseases. Synthesis of a hydrogel composed of hyaluronic acid and a poloxamer blend was undertaken. Poly(D,L-lactide-co-glycolide) acid nanoparticles encapsulating triamcinolone acetonide (TA) were synthesised with a spherical morphology and mean diameter of ~ 153 nm. Hydrogel fabrication and nanoparticle loading within the hydrogel was confirmed via physicochemical analysis. Gelation studies indicated that hydrogels formed in nine minutes and 10 min for the unloaded and nanoparticle-loaded hydrogels, respectively. The hydrogels displayed in situ gel formation properties, and rheometric viscoelastic studies indicated the unloaded and loaded hydrogels to have modulus values similar to those of the natural vitreous at 37 °C. Administration of the hydrogels was possible via 26G needles allowing for clinical application and drug release of triamcinolone acetonide from the nanoparticle-loaded hydrogel, which provided sustained in vitro drug release over nine weeks. The hydrogels displayed minimal swelling, reaching equilibrium swelling within 12 h for the unloaded hydrogel, and eight hours for the nanoparticle-loaded hydrogel. Biodegradation in simulated vitreous humour with lysozyme showed < 20% degradation within nine weeks. Biocompatibility of both unloaded and loaded hydrogels was shown with mouse fibroblast and human retinal pigment epithelium cell lines. Lastly, a pilot in vivo study in a New Zealand White rabbit model displayed minimal toxicity with precise, localised drug release behaviour, and ocular TA levels maintained within the therapeutic window for the 28-day investigation period, which supports the potential applicability of the unloaded and nanoparticle-loaded hydrogels as vitreous substitutes that function as drug delivery systems following vitrectomy surgery.
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Affiliation(s)
- Kruti Naik
- Wits Advanced Drug Delivery Platform Research Unit, Department of Pharmacy and Pharmacology, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Johannesburg, Parktown, 2193, South Africa
| | - Lisa Claire du Toit
- Wits Advanced Drug Delivery Platform Research Unit, Department of Pharmacy and Pharmacology, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Johannesburg, Parktown, 2193, South Africa
| | - Naseer Ally
- Division of Ophthalmology, Department of Neurosciences, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Johannesburg, Parktown, 2193, South Africa
| | - Yahya Essop Choonara
- Wits Advanced Drug Delivery Platform Research Unit, Department of Pharmacy and Pharmacology, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Johannesburg, Parktown, 2193, South Africa.
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Qu S, Tang Y, Ning Z, Zhou Y, Wu H. Desired properties of polymeric hydrogel vitreous substitute. Biomed Pharmacother 2024; 172:116154. [PMID: 38306844 DOI: 10.1016/j.biopha.2024.116154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/06/2024] [Accepted: 01/10/2024] [Indexed: 02/04/2024] Open
Abstract
Vitreous replacement is a commonly employed method for treating a range of ocular diseases, including posterior vitreous detachment, complex retinal detachment, diabetic retinopathy, macular hole, and ocular trauma. Various clinical substitutes for vitreous include air, expandable gas, silicone oil, heavy silicone oil, and balanced salt solution. However, these substitutes have drawbacks such as short retention time, cytotoxicity, high intraocular pressure, and the formation of cataracts, rendering them unsuitable for long-term treatment. Polymeric hydrogels possess the potential to serve as ideal vitreous substitutes due to their structure-mimicking to natural vitreous and adjustable mechanical properties. Replacement with hydrogels as the tamponade can help maintain the shape of the eyeball, apply pressure to the detached retina, and ensure the metabolic transport of substances without impairing vision. This literature review examines the required properties of artificial vitreous, including the optical properties, rheological properties, expansive force action, and physiological and biochemical functions of chemically and physically crosslinked hydrogels. The strategies for enhancing the biocompatibility and injectability of hydrogels are also summarized and discussed. From a clinical ophthalmology perspective, this paper presents the latest developments in vitreous replacement, providing clinicians with a comprehensive understanding of hydrogel clinical applications, which offers guidance for future design directions and methodologies for hydrogel development.
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Affiliation(s)
- Sheng Qu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130041, China
| | - Yi Tang
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130041, China
| | - Zichao Ning
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130041, China
| | - Yanjie Zhou
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130041, China
| | - Hong Wu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130041, China.
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3
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Choi G, An SH, Choi JW, Rho MS, Park WC, Jeong WJ, Cha HJ. Injectable alginate-based in situ self-healable transparent hydrogel as a vitreous substitute with a tamponading function. Biomaterials 2024; 305:122459. [PMID: 38199216 DOI: 10.1016/j.biomaterials.2023.122459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/24/2023] [Accepted: 12/30/2023] [Indexed: 01/12/2024]
Abstract
Retinal detachment and other vision-threatening disorders often necessitate vitreous body removal and tamponade injection for retina stabilization. Current clinical tamponades such as silicone oil and expansile gases have drawbacks, including patient discomfort and the need for secondary surgery. We introduce a transparent alginate-phenylboronic acid/polyvinyl alcohol composite hydrogel (TALPPH) as a novel vitreous substitute with tamponading capabilities. In vitro physicochemical, rheological, and optical characterization of in situ self-healable TALPPH was performed, and long-term biocompatibility was assessed in a rabbit model of vitrectomy retinal detachment. In vivo evaluations confirmed TALPPH's ability to inhibit retinal detachment recurrence and preserve rabbit vision without adverse effects. TALPPH's close resemblance to the natural vitreous body suggests potential as a vitreous tamponade substitute for future ophthalmological applications.
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Affiliation(s)
- Geunho Choi
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Seoung Hyun An
- Department of Ophthalmology, Dong-A University Hospital, Busan 49315, Republic of Korea
| | - Jae-Won Choi
- Department of Ophthalmology, Sungmo Eye Hospital, Busan 48064, Republic of Korea
| | - Mee Sook Rho
- Department of Pathology, Dong-A University Hospital, Busan 49315, Republic of Korea
| | - Woo Chan Park
- Department of Ophthalmology, Dong-A University Hospital, Busan 49315, Republic of Korea
| | - Woo Jin Jeong
- Department of Ophthalmology, Dong-A University Hospital, Busan 49315, Republic of Korea.
| | - Hyung Joon Cha
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea; Medical Science and Engineering, School of Convergence Science and Technology, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
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4
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Mimura M, Akagi T, Kohmoto R, Fujita Y, Sato Y, Ikeda T. Measurement of vitreous humor pressure in vivo using an optic fiber pressure sensor. Sci Rep 2023; 13:18233. [PMID: 37880357 PMCID: PMC10600124 DOI: 10.1038/s41598-023-45616-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 10/21/2023] [Indexed: 10/27/2023] Open
Abstract
We conducted a study to assess the pressure difference between the aqueous and vitreous humors in rabbit eyes using a direct intraocular pressure (IOP) measurement method. A micro-optic-fiber pressure sensor was utilized for this purpose. Preliminary experiments with enucleated porcine eyes confirmed the sensor's accuracy in measuring both aqueous and vitreous humor pressure. The main study involved six healthy albino rabbits, where the sensor measured the pressure in the anterior chamber (aIOP) and posterior vitreous-cavity (pIOP). These measurements were compared to aIOP values obtained through rebound tonometry. Additionally, pre- and postoperative pressure comparisons were made after performing a vitrectomy. Results revealed a significant disparity between aqueous and vitreous humor pressures. Prior to vitrectomy, pIOP was 22.8 mmHg, over twice as high as aIOP (11.0 mmHg), but decreased to a similar level following the procedure. Comparison between the sensor measurements and rebound tonometry showed agreement in aIOP values. In conclusion, our study demonstrates that vitreous humor pressure is consistently higher than aqueous humor pressure, reaching the upper limit of normal IOP. Furthermore, vitrectomy effectively reduces pIOP, aligning it with aIOP. These findings contribute valuable insights into intraocular pressure dynamics and have implications for clinical interventions targeting ocular pressure regulation.
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Affiliation(s)
- Masashi Mimura
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan.
- Department of Ophthalmology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo , 663-8501, Japan.
- Department of Ophthalmology, Toho University Sakura Medical Center, Sakura-City, Chiba, Japan.
| | - Tadamichi Akagi
- Division of Ophthalmology and Visual Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ryosuke Kohmoto
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Yasushi Fujita
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Yohei Sato
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Tsunehiko Ikeda
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
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Zu H, Zhang K, Zhang H, Qian X. An Inverse Method to Determine Mechanical Parameters of Porcine Vitreous Bodies Based on the Indentation Test. Bioengineering (Basel) 2023; 10:646. [PMID: 37370577 DOI: 10.3390/bioengineering10060646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
The vitreous body keeps the lens and retina in place and protects these tissues from physical insults. Existing studies have reported that the mechanical properties of vitreous body varied after liquefaction, suggesting mechanical properties could be effective parameters to identify vitreous liquefaction process. Thus, in this work, we aimed to propose a method to determine the mechanical properties of vitreous bodies. Fresh porcine eyes were divided into three groups, including the untreated group, the 24 h liquefaction group and the 48 h liquefaction group, which was injected collagenase and then kept for 24 h or 48 h. The indentation tests were carried out on the vitreous body in its natural location while the posterior segment of the eye was fixed in the container. A finite element model of a specimen undertaking indentation was constructed to simulate the indentation test with surface tension of vitreous body considered. Using the inverse method, the mechanical parameters of the vitreous body and the surface tension coefficient were determined. For the same parameter, values were highest in the untreated group, followed by the 24 h liquefaction group and the lowest in the 48 h liquefaction group. For C10 in the neo-Hookean model, the significant differences were found between the untreated group and liquefaction groups. This work quantified vitreous body mechanical properties successfully using inverse method, which provides a new method for identifying vitreous liquefactions related studies.
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Affiliation(s)
- Haicheng Zu
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
| | - Kunya Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
| | - Haixia Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
| | - Xiuqing Qian
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
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Sridhar V, Yildiz E, Rodríguez-Camargo A, Lyu X, Yao L, Wrede P, Aghakhani A, Akolpoglu BM, Podjaski F, Lotsch BV, Sitti M. Designing Covalent Organic Framework-Based Light-Driven Microswimmers toward Therapeutic Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2301126. [PMID: 37003701 DOI: 10.1002/adma.202301126] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/18/2023] [Indexed: 06/19/2023]
Abstract
While micromachines with tailored functionalities enable therapeutic applications in biological environments, their controlled motion and targeted drug delivery in biological media require sophisticated designs for practical applications. Covalent organic frameworks (COFs), a new generation of crystalline and nanoporous polymers, offer new perspectives for light-driven microswimmers in heterogeneous biological environments including intraocular fluids, thus setting the stage for biomedical applications such as retinal drug delivery. Two different types of COFs, uniformly spherical TABP-PDA-COF sub-micrometer particles and texturally nanoporous, micrometer-sized TpAzo-COF particles are described and compared as light-driven microrobots. They can be used as highly efficient visible-light-driven drug carriers in aqueous ionic and cellular media. Their absorption ranging down to red light enables phototaxis even in deeper and viscous biological media, while the organic nature of COFs ensures their biocompatibility. Their inherently porous structures with ≈2.6 and ≈3.4 nm pores, and large surface areas allow for targeted and efficient drug loading even for insoluble drugs, which can be released on demand. Additionally, indocyanine green (ICG) dye loading in the pores enables photoacoustic imaging, optical coherence tomography, and hyperthermia in operando conditions. This real-time visualization of the drug-loaded COF microswimmers enables unique insights into the action of photoactive porous drug carriers for therapeutic applications.
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Affiliation(s)
- Varun Sridhar
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Erdost Yildiz
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Andrés Rodríguez-Camargo
- Nanochemistry Department, Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
- Department of Chemistry, University of Stuttgart, 70569, Stuttgart, Germany
| | - Xianglong Lyu
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Liang Yao
- Nanochemistry Department, Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Paul Wrede
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland
| | - Amirreza Aghakhani
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Birgul M Akolpoglu
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland
| | - Filip Podjaski
- Nanochemistry Department, Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
- Department of Chemistry, Imperial College London, W12 0BZ, London, UK
| | - Bettina V Lotsch
- Nanochemistry Department, Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
- Department of Chemistry, University of Stuttgart, 70569, Stuttgart, Germany
- Cluster of Excellence e-conversion, 85748, Lichtenbergstrasse 4, Garching, Germany
- Department of Chemistry, University of Munich (LMU), 81377, Munich, Germany
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Institute for Biomedical Engineering, ETH Zurich, 8092, Zurich, Switzerland
- School of Medicine and College of Engineering, Koç University, 34450, Istanbul, Turkey
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Hollister JCP, Rodriguez M, Hosseini H, Papour A, Hubschman JP, Kavehpour HP. Ultrasonic Vitrectomy Performance Assessment Using Micro-Extensional Rheology. Transl Vis Sci Technol 2023; 12:24. [PMID: 36790819 PMCID: PMC9940767 DOI: 10.1167/tvst.12.2.24] [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] [Indexed: 02/16/2023] Open
Abstract
Purpose The purpose of this study was to assess the performance of ultrasonic (US) vitrectomy devices by quantifying and comparing its impact on extracted vitreous properties to conventional pneumatic blade (PB) cutters using micro-extensional rheology. US vitrectomy is a new technology that offers an alternative to PB cutters used in vitreo-retinal surgeries. Methods Thirty-six porcine vitreous samples were extracted using US and PB cutters. Each sample was kept at 4°C and tested within 24 hours postmortem and 4 hours post-vitrectomy. A recently developed micro-extensional rheology technique is used to infer the relative protein fragment size of extracted vitreous by quantifying the extensional relaxation time. Results US-extracted vitreous exhibited extensional relaxation times orders of magnitude lower than PB-extracted vitreous (0.37 ms and 27.25 ms, respectively). Relaxation time is directly correlated to the fragment size of the collagen fibers in the vitreous. The formation of beads-on-a-string droplets within the PB samples indicates the presence of larger collagen fragments. These droplets were not seen on US samples. Conclusions This new micro-extensional rheology technique can identify significant differences in physical properties of extracted vitreous. Long relaxation times and beads-on-a-string droplets within the PB vitreous samples indicate larger protein fragments compared to the US samples. Translational Relevance Higher fragmentation of vitreous and lower extensional relaxation times may improve retina safety due to a reduction in vitreo-retinal traction resulting from the continuous shear action and aspiration applied by ultrasonic vitrectomy technology.
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Affiliation(s)
- John C. P. Hollister
- Department of Mechanical and Aerospace Engineering, University of California – Los Angeles, Los Angeles, CA, USA
| | - Mercedes Rodriguez
- Stein Eye Institute, University of California – Los Angeles, Los Angeles, CA, USA
| | - Helia Hosseini
- Department of Bioengineering, University of California – Los Angeles, Los Angeles, CA, USA
| | | | | | - H. Pirouz Kavehpour
- Department of Mechanical and Aerospace Engineering, Department of Bioengineering, University of California – Los Angeles, Los Angeles, CA, USA
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Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery. Int J Mol Sci 2023; 24:ijms24043342. [PMID: 36834754 PMCID: PMC9961686 DOI: 10.3390/ijms24043342] [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: 12/20/2022] [Revised: 01/24/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.
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Phillips JD, Hwang ES, Morgan DJ, Creveling CJ, Coats B. Structure and mechanics of the vitreoretinal interface. J Mech Behav Biomed Mater 2022; 134:105399. [PMID: 35963021 PMCID: PMC9552593 DOI: 10.1016/j.jmbbm.2022.105399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 07/17/2022] [Accepted: 07/24/2022] [Indexed: 12/24/2022]
Abstract
Vitreoretinal mechanics plays an important role in retinal trauma and many sight-threatening diseases. In age-related pathologies, such as posterior vitreous detachment and vitreomacular traction, lingering vitreoretinal adhesions can lead to macular holes, epiretinal membranes, retinal tears and detachment. In age-related macular degeneration, vitreoretinal traction has been implicated in the acceleration of the disease due to the stimulation of vascular growth factors. Despite this strong mechanobiological influence on trauma and disease in the eye, fundamental understanding of the mechanics at the vitreoretinal interface is limited. Clarification of adhesion mechanisms and the role of vitreoretinal mechanics in healthy eyes and disease is necessary to develop innovative treatments for these pathologies. In this review, we evaluate the existing literature on the structure and function of the vitreoretinal interface to gain insight into age- and region-dependent mechanisms of vitreoretinal adhesion. We explore the role of vitreoretinal adhesion in ocular pathologies to identify knowledge gaps and future research areas. Finally, we recommend future mechanics-based studies to address the critical needs in the field, increase fundamental understanding of vitreoretinal mechanisms and disease, and inform disease treatments.
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Affiliation(s)
- Joseph D Phillips
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Eileen S Hwang
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States
| | - Denise J Morgan
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, United States
| | | | - Brittany Coats
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, United States.
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Kasireddy N, Orie JC, Khismatullin DB. Drop-of-sample rheometry of biological fluids by noncontact acoustic tweezing spectroscopy. LAB ON A CHIP 2022; 22:3067-3079. [PMID: 35851909 PMCID: PMC10661770 DOI: 10.1039/d2lc00356b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Knowledge of rheological properties, such as viscosity and elasticity, is necessary for efficient material processing and transportation as well as biological analysis. Existing rheometers operate with large sample volume and induce sample contact with container or device walls, which are inadequate for rheological analysis of sensitive fluids limited in availability. In this work, we introduce acoustic tweezing spectroscopy (ATS), a novel noncontact rheological technique that operates with a single 4-6 μl drop of fluid sample. In ATS, a sample drop is acoustically levitated and then exposed to a modulated acoustic signal to induce its forced oscillation. The time-dependent sample viscosity and elasticity are measured from the resulting drop response. The ATS measurements of polymeric solutions (dextran, xanthan gum, gelatin) agree well with previously reported data. The ATS predicts that the shear viscosity of blood plasma increases from 1.5 cP at 1.5 min of coagulation onset to 3.35 cP at 9 min, while its shear elastic modulus grows from a negligible value to 10.7 Pa between 3.5 min and 6.5 min. Coagulation increases whole blood viscosity from 5.4 cP to 20.7 cP and elasticity from 0.1 Pa to 19.2 Pa at 15 min. In summary, ATS provides the opportunity for sensitive small-volume rheological analysis in biomedical research and medical, pharmaceutical, and chemical industries.
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Affiliation(s)
- Nithya Kasireddy
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans, Louisiana, 70118, USA.
| | - Jeremy C Orie
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans, Louisiana, 70118, USA.
| | - Damir B Khismatullin
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans, Louisiana, 70118, USA.
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11
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Yeast-produced fructosamine-3-kinase retains mobility after ex vivo intravitreal injection in human and bovine eyes as determined by Fluorescence Correlation Spectroscopy. Int J Pharm 2022; 621:121772. [PMID: 35487399 DOI: 10.1016/j.ijpharm.2022.121772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 11/20/2022]
Abstract
Globally, over 2 billion people suffer from vision impairment. Despite complex multifactorial etiology, advanced glycation end products are involved in the pathogenesis of many causative age- and diabetes-related eye diseases. Deglycating enzyme fructosamine-3-kinase (FN3K) was recently proposed as a potential therapeutic, but for further biopharmaceutical development, knowledge on its manufacturability and stability and mobility in the vitreous fluid of the eye is indispensable. We evaluated recombinant production of FN3K in two host systems, and its diffusion behavior in both bovine and human vitreous. Compared to Escherichia coli, intracellular production in Pichia pastoris yielded more and higher purity FN3K. The yeast-produced enzyme was used in a first attempt to use fluorescence correlation spectroscopy to study protein mobility in non-sonicated bovine vitreous, human vitreous, and intact bovine eyes. It was demonstrated that FN3K retained mobility upon intravitreal injection, although a certain delay in diffusion was observed. Alkylation of free cysteines was tolerated both in terms of enzymatic activity and vitreous diffusion. Ex vivo diffusion data gathered and the availability of yeast-produced high purity enzyme now clear the path for in vivo pharmacokinetics studies of FN3K.
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12
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Ocular biomechanics during improvised explosive device blast: A computational study using eye-specific models. Injury 2022; 53:1401-1415. [PMID: 35144807 PMCID: PMC8940691 DOI: 10.1016/j.injury.2022.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/27/2022] [Accepted: 02/03/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Eye injuries comprise 10-13% of civilian improvised explosive device (IED) injuries. The bomb blast wave induces a normal and shear forces on the tissues, causing a large acute IOP elevation. This study calculated the biomechanical stresses and strains in the eye due to IED explosion via eye-specific fluid-structure interaction (FSI) models. METHODS Blast occurred at 2, 3, and 4 m from the front and side of the victim and the weights of the IED were 1 and 2 kg. The ground was covered with the deformable soil to mimic the realistic IED explosion condition and reflect the blast wave. RESULTS The IOP elevation of ∼6,000-48,000 mmHg was observed in the eyes while the highest IOP was occurred with the IED weight and distance of 2 kg and 2 m (front) and the lowest was occurred with the IED weight and distance of 1 kg and 4 m (side). Our findings suggest the importance of the victim location and orientation concerning the blast wave when it comes to ocular injury assessment. IOP elevation of ∼2900 and ∼2700 mmHg were observed in ∼1.6 ms after the blast for the IEDS weight of 2 kg and a victim distance of 2 m in front and side blasts, respectively, in consistence with the literature. Nonetheless, IOPs were considerably higher after ∼1.6 ms due to the merging of the bomb blast wave and its reflection off the ground. CONCLUSIONS The stresses and strains were highest for the frontal blast. Both side and frontal blasts caused higher stresses and strains at the rectus muscle insertions where the sclera is thinnest and prone to rupture. Blast angle has no considerable role in the resultant IOP. Front blast with a heavier IED resulted a higher stresses and deformations in the eye connective tissues compared to the side blast.
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13
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Srikantha N, Teijeiro-Gonzalez Y, Simpson A, Elsaid N, Somavarapu S, Suhling K, Jackson TL. Determining vitreous viscosity using fluorescence recovery after photobleaching. PLoS One 2022; 17:e0261925. [PMID: 35143514 PMCID: PMC8830689 DOI: 10.1371/journal.pone.0261925] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 12/14/2021] [Indexed: 01/22/2023] Open
Abstract
PURPOSE Vitreous humor is a complex biofluid whose composition determines its structure and function. Vitreous viscosity will affect the delivery, distribution, and half-life of intraocular drugs, and key physiological molecules. The central pig vitreous is thought to closely match human vitreous viscosity. Diffusion is inversely related to viscosity, and diffusion is of fundamental importance for all biochemical reactions. Fluorescence Recovery After Photobleaching (FRAP) may provide a novel means of measuring intravitreal diffusion that could be applied to drugs and physiological macromolecules. It would also provide information about vitreous viscosity, which is relevant to drug elimination, and delivery. METHODS Vitreous viscosity and intravitreal macromolecular diffusion of fluorescently labelled macromolecules were investigated in porcine eyes using fluorescence recovery after photobleaching (FRAP). Fluorescein isothiocyanate conjugated (FITC) dextrans and ficolls of varying molecular weights (MWs), and FITC-bovine serum albumin (BSA) were employed using FRAP bleach areas of different diameters. RESULTS The mean (±standard deviation) viscosity of porcine vitreous using dextran, ficoll and BSA were 3.54 ± 1.40, 2.86 ± 1.13 and 4.54 ± 0.13 cP respectively, with an average of 3.65 ± 0.60 cP. CONCLUSIONS FRAP is a feasible and practical optical method to quantify the diffusion of macromolecules through vitreous.
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Affiliation(s)
- Nishanthan Srikantha
- School of Medicine, King’s College London, London, United Kingdom
- Department of Ophthalmology, King’s College Hospital, London, United Kingdom
- * E-mail:
| | | | - Andrew Simpson
- School of Medicine, King’s College London, London, United Kingdom
- Department of Ophthalmology, King’s College Hospital, London, United Kingdom
| | - Naba Elsaid
- Anglia Ruskin University, Bishop Hall Lane, Chelmsford, United Kingdom
| | - Satyanarayana Somavarapu
- Department of Pharmaceutics, University College London School of Pharmacy, London, United Kingdom
| | - Klaus Suhling
- Department of Physics, King’s College London, Strand, London, United Kingdom
| | - Timothy L. Jackson
- School of Medicine, King’s College London, London, United Kingdom
- Department of Ophthalmology, King’s College Hospital, London, United Kingdom
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Lee J, Rhee YS. Ophthalmic dosage forms for drug delivery to posterior segment. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2022. [DOI: 10.1007/s40005-021-00554-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Karimi A, Razaghi R, Girkin CA, Downs JC. Ocular biomechanics due to ground blast reinforcement. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 211:106425. [PMID: 34598082 PMCID: PMC8577623 DOI: 10.1016/j.cmpb.2021.106425] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/14/2021] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND OBJECTIVE Bomb blast injuries exerts a shearing force on the air-tissue interfaces, causing devastating ocular injury from the blast wave. Improvised explosive devices (IEDs) are usually placed at different heights from the ground to induce more severe injury through ground blast reinforcement (GBR). However, there is still a lack of knowledge of the role of GBR and IED height from the ground on ocular biomechanics, and how they can affect the intraocular pressure (IOP) in the eye. This study aimed to estimate the IOP due to frontal IED explosion at different heights from the ground using a fluid-structure interaction model with and without GBR effects. METHODS A 2 kg IED was placed within 5 m of the victim at 5 different heights from the ground, including 0, 0.42, 0.85, 1.27, and 1.70 m. Two different blast formulations were used to simulate the IED explosion: (a) spherical airburst, with no amplification of the initial shock wave due to interaction with the ground-surface, and (b) hemispherical surface-burst, where the initial blast wave is immediately reflected and reinforced by the ground (GBR). RESULTS Results revealed that the blast wave due to GBR reaches to the skull prior to the IED blast itself. The GBR also reached to the skull ∼ 0.6 ms earlier when the IED was on the ground compared to the height of 1.70 m. The highest and lowest IOPs of ∼ 17,000 and ∼ 15,000 mmHg were observed at the IED heights of 1.70 and 0 m from the ground considering GBR. However, when the role of the GBR is ignored, IOP of ∼ 9,000 mmHg was observed regardless of the IED height from the ground. The deformation in the apex of the cornea was higher when considering the GBR (∼ 0.75 cm) versus no GBR (∼ 0.65 cm). Considering GBR led to higher stresses and strains in the sclera. CONCLUSIONS When the role of GBR was ignored, the results showed similar patterns and magnitudes of stresses and deformations in the skull and eye regardless of the height of the IED from the ground, which was not the case when GBR was considered. The findings of this study suggest the critical role of GBR in ocular blast simulations.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 390A, Birmingham, AL 35294, United States.
| | - Reza Razaghi
- Research Department, Heel of Scene Ltd., 2 Chome-12-3 Honmachi, Shibuya City, Tokyo, Japan.
| | - Christopher A Girkin
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 390A, Birmingham, AL 35294, United States.
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 390A, Birmingham, AL 35294, United States.
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Chen D, Liu X, Geng X, Huo H, Dong Y, Tang M, Tang Z, Qiao X, Fan Y. A simple indentation technique for identifying localized liquefaction of the vitreous body. J Biomech 2021; 129:110795. [PMID: 34662756 DOI: 10.1016/j.jbiomech.2021.110795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/17/2021] [Accepted: 10/04/2021] [Indexed: 11/16/2022]
Abstract
Identification of vitreous liquefaction (VL) is important for investigating some eye pathologies related to changes in the mechanical properties of the vitreous, such as posterior vitreous detachment or retinal detachment. However, because of the extremely high-water content, characterization of the structural and mechanical properties of the vitreous remains a challenge. In the current study, a simple indentation test was performed on the fresh vitreous, partially liquefied vitreous and water, using a mechanical testing machine with a high-precision load cell. Pressure loads on the indenter changing with time for different samples were obtained to characterize their mechanical properties. VL identification was achieved based on a comparison of relative differences in some typical mechanical parameters (e.g. the pressure at the moment of the insertion (P0), the pressure at the steady mechanical state (P∞) and the time when the pressure on the indenter declined to one half the initial value (t1/2)) between 1) partially liquefied vitreous and fresh vitreous samples and 2) partially liquefied vitreous and water samples. The results indicated that P0 of the partially liquefied vitreous was almost half that of fresh vitreous (p < 0.05) and approximately 1.5 times that of water (p < 0.05). t1/2 of the partially liquefied vitreous was approximately 1.4 times higher than that of fresh vitreous (p < 0.05) and approximately 80% of that of water (p < 0.05). It is concluded that P0 and t1/2 can be used as indicators to identify localized liquefaction of the vitreous.
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Affiliation(s)
- Duo Chen
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaoyu Liu
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; School of Medical Science and Engineering Medicine, Beihang University, Beijing 100083, China.
| | - Xiaoqi Geng
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Hongqiang Huo
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Ying Dong
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Min Tang
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Zhili Tang
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaofeng Qiao
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yubo Fan
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; School of Medical Science and Engineering Medicine, Beihang University, Beijing 100083, China; State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing 100083, China.
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17
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Aboulatta A, Abass A, Makarem A, Eliasy A, Zhou D, Chen D, Liu X, Elsheikh A. Experimental evaluation of the viscoelasticity of porcine vitreous. J R Soc Interface 2021; 18:20200849. [PMID: 33530856 DOI: 10.1098/rsif.2020.0849] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study aims to estimate the material properties of the porcine vitreous while testing it in close to its natural physiological conditions. Eighteen porcine eyes were tested within 48 h post-mortem. A custom-built computer-controlled test rig was designed to support, load and monitor the behaviour of eye globes while being subjected to dynamic rotation cycles mimicking saccade eye movement. Specimens were glued to the base of a container, surrounded by gelatin, frozen and cut in half to expose the vitreous. After thawing, the container was subjected to concentric dynamic rotations of up to 5°, 10° or 15°, while taking 50 MP photos of the specimen every 2 ms. The images were analysed by a digital image correlation algorithm to trace the movement of marked points on the vitreous surface with different radii from the centre of the posterior chamber. The initial camera image was used in building a finite-element model of the test set-up, which was used in an inverse analysis exercise to estimate the material properties of the vitreous. Angular displacements of the monitored points were up to 3.3°, 4.1° and 3.9° in response to eye rotations of 5°, 10° and 15°, respectively. With the experimental relationships between eye rotation and angular displacements used as target behaviour, the inverse analysis exercise estimated the initial shear modulus, the long-term shear modulus and the viscoelastic decay constant of the porcine vitreous as 2.10 ± 0.15 Pa, 0.50 ± 0.04 Pa and 1.20 ± 0.09 s-1, respectively. Consideration of the viscoelasticity of the vitreous was essential to represent its experimental behaviour. Testing the vitreous in close to its normal physiological conditions produced estimations of the initial shear modulus and long-term shear modulus that were, respectively, smaller and larger than reported values (Zimberlin et al. 2010 Soft Matter 6, 3632-3635. (doi:10.1039/b925407b), Liu et al. 2013 J. Biomech. 46, 1321-7. (doi:10.1016/j.jbiomech.2013.02.006), Rossi et al. 2011 Invest. Ophthalmol. Vis. Sci. 52, 3994-4002. (doi:10.1167/iovs.10-6477)).
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Affiliation(s)
- Ali Aboulatta
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ahmed Makarem
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Dong Zhou
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Duo Chen
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, People's Republic of China
| | - Xiaoyu Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, People's Republic of China.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, People's Republic of China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, People's Republic of China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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18
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Experimental assessment of the performance of vitreous cutters with fluids with different rheological properties. Graefes Arch Clin Exp Ophthalmol 2021; 259:1113-1121. [PMID: 33394160 DOI: 10.1007/s00417-020-05061-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/02/2020] [Accepted: 12/21/2020] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To assess the influence of rheological properties of an artificial vitreous (AV) on the performance of double-blade (DB) and single-blade (SB) guillotine vitreous cutters, with 23-, 25-, and 27-gauge (G) probes. METHODS We evaluate the aspiration flow rate, using an optical method, based on image processing. Experiments are conducted using ten viscoelastic vitreous phantoms, with different properties that are measured with rheological tests. RESULTS Aspiration rate strongly varies with fluid properties. Regardless of cutter geometry and operational conditions, the flow rate significantly decreases as vitreous viscosity and elasticity increase. CONCLUSIONS All tested vitreous probes are very sensitive to changes in fluid rheology. SB cutters produce smaller flow rates compared with DB ones of the same caliber; however, they are less sensitive to fluid properties at low aspiration pressures. The use of vitreous substitutes for test performance guarantees comparability between flow rate results achieved with different vitrectomy systems operating in different media. This outcome is further confirmed by the low values of estimated flow rate relative errors.
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19
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Uthoff D, Oravecz R, Kuehnl R, Rubin-Schwarz F, Frentzen M, Schrage N, Meister J. A promising approach in laser vitrectomy executed by plasma-mediated removal of vitreous body via a diode-pumped Q-switched Nd:YAG laser. Sci Rep 2020; 10:21710. [PMID: 33303956 PMCID: PMC7730428 DOI: 10.1038/s41598-020-78878-y] [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: 07/18/2020] [Accepted: 11/23/2020] [Indexed: 11/09/2022] Open
Abstract
To examine the applicability of plasma-mediated vitreous body removal, a diode-pumped Q-switched Neodymium:YAG laser was used for a possible application in eye surgery/vitrectomy. On a total of 1500 porcine vitreous bodies, removal rates were evaluated by comparing different LaserVit-tip designs (Mark I/II Gauge 19 and Mark III Gauge 22). The Nd:YAG laser, operating at a wavelength of 1064 nm and a pulse duration of 4 ns, was utilized for vitreous body removal with respective settings of 2, 3 and 4 mJ and pulse repetition rates (cut rates) from 5 to 25 Hz (300–1500 /min) in 5 Hz-steps as well as for 100 Hz (6000 cuts/min). The exposure times were selected at 10, 20, 40 and 60 s, respectively. Comparative measurements were carried out with mechanical cutters (Gauge 20 and Gauge 23), applying a fixed cut rate of 800 /min (13.33 Hz) at identical exposure times. The LaserVit-tips showed successful vitreous body removal for all laser settings and exposure times (Mark I: 6.2 g/min, Mark II: 8.2 g/min at 1500 cuts/min and 3 mJ, Mark II: 10.1 g/min, Mark III: 3.6 g/min at 6000 cuts/min at 3 mJ). Similar tip-dimensions (Gauge 22laser and Gauge 23cutter) showed comparable removal rates of 3.6 g/minlaser and 1.3 g/mincutter with settings of 6000 cuts/min at 3 mJ (laser) and 800 cuts/min for the mechanical cutter. A diode-pumped Q-switched Nd:YAG laser can successfully and gently remove vitreous body. The efficiency of the laser was comparable to that of mechanical cutters in terms of quantity of material removed per time unit.
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Affiliation(s)
- Daniel Uthoff
- Aachen Center of Technology Transfer in Ophthalmology (ACTO E.V.), An-Institute RWTH Aachen University, Karlsburgweg 9, 52070, Aachen, Germany.
| | - Rita Oravecz
- Aachen Center of Technology Transfer in Ophthalmology (ACTO E.V.), An-Institute RWTH Aachen University, Karlsburgweg 9, 52070, Aachen, Germany
| | - Romina Kuehnl
- University of Applied Sciences Ansbach, Ansbach, Germany
| | | | - Matthias Frentzen
- Department of Operative and Preventive Dentistry, Bonn University, Bonn, Germany
| | - Norbert Schrage
- Aachen Center of Technology Transfer in Ophthalmology (ACTO E.V.), An-Institute RWTH Aachen University, Karlsburgweg 9, 52070, Aachen, Germany
| | - Jörg Meister
- Center of Dento-Maxillo-Facial Medicine, Bonn University, Bonn, Germany.,Center of Applied Medical Laser Research and Biomedical Optics (AMLaReBO), Bonn University, Bonn, Germany
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20
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de Santana JM, Cordeiro GG, Soares DTC, Costa MR, Paashaus da Costa Pinto A, Lira RPC. Use of axial length to estimate the vitreous chamber volume in pseudophakic. Graefes Arch Clin Exp Ophthalmol 2020; 259:1471-1475. [PMID: 33141255 DOI: 10.1007/s00417-020-04991-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/28/2020] [Accepted: 10/22/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE To develop an equation for estimating the vitreous chamber volume in pseudophakic patients based on the axial length of the eye. METHODS A consecutive series of patients who underwent vitrectomy surgery for a macular hole or an epiretinal membrane were enrolled. The inclusion criteria were as follows: having pseudophakia, being older than 50 years, and having eyes with axial length ranging from 21 to 26 mm. Before the surgery, the axial length was measured using optical biometry. Pars plan vitrectomy was performed, and, after the fluid-air exchange, the vitreous chamber was filled with Brilliant Blue G (0.005%). The infused volume of each eye was recorded. Then, epiretinal membrane peeling or internal limiting membrane peeling and a new fluid-air exchange were performed. Main outcomes and measures were the vitreous chamber volume and axial length. RESULTS The sample consisted of 112 patients. The mean [standard deviation (SD), range] age was 71 years (7, 53-90). Sixty-five individuals (58%) were women. In 58 (51.8%) patients, surgery was performed on the right eye. The mean (SD; range) axial length was 23.78 mm (0.93; 21.55-25.26), and the mean (SD; range) vitreous chamber volume was 4.96 mL (0.69; 3.60-6.40). Pearson's correlation coefficient (r = 0.950; p < 0.01) was positive, and the coefficient of determination (R2) was 0.902. The estimated regression equation was Y = 0.71X - 11.84, where Y was the vitreous chamber volume, X was the axial length of the eye, the linear coefficient for the straight line was - 11.83, and the angular coefficient was 0.71 (p < 0.01). CONCLUSION These data suggest that the vitreous chamber volume is significantly correlated with the axial length and the former could probably be calculated using biometry. New studies with larger samples will be required to confirm these observations and will allow the development of an algorithm (perhaps non-linear) that includes extreme axial length values and that takes into account other factors such as the status of the lens and sex.
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Tram NK, Maxwell CJ, Swindle-Reilly KE. Macro- and Microscale Properties of the Vitreous Humor to Inform Substitute Design and Intravitreal Biotransport. Curr Eye Res 2020; 46:429-444. [PMID: 33040616 DOI: 10.1080/02713683.2020.1826977] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested in vitro, has been hypothesized to be different in vivo. Future studies should focus on testing the mechanical properties of the vitreous in situ or in vivo. In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport.
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Affiliation(s)
- Nguyen K Tram
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Courtney J Maxwell
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Katelyn E Swindle-Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.,William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, USA.,Department of Ophthalmology & Visual Science, The Ohio State University, Columbus, OH, USA
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Bayat J, Emdad H, Abouali O. 3D numerical investigation of the fluid mechanics in a partially liquefied vitreous humor due to saccadic eye movement. Comput Biol Med 2020; 125:103955. [DOI: 10.1016/j.compbiomed.2020.103955] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 10/23/2022]
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23
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Rangchian A, Hubschman JP, Kavehpour HP. Time dependent degradation of vitreous gel under enzymatic reaction: Polymeric network role in fluid properties. J Biomech 2020; 109:109921. [DOI: 10.1016/j.jbiomech.2020.109921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 02/06/2023]
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A drug delivery analysis of large molecules in ocular vitreous chamber: Dependency on saccadic movements after intravitreal injection. Med Eng Phys 2020; 82:49-57. [PMID: 32709265 DOI: 10.1016/j.medengphy.2020.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 05/14/2020] [Accepted: 06/15/2020] [Indexed: 02/06/2023]
Abstract
The purpose of this study is to investigate the effect of vitreous sloshing induced by saccades on the intravitreal delivery of large molecule drugs. The vitreous body was considered in its age-related liquefaction condition. Fluid dynamics and large molecule distribution were described by the coupling of mass conservation's and Fick's laws with continuity and momentum equations for a Newtonian incompressible fluid in a 3D unsteady analysis. Two injection sites were analyzed, in both the mixing effect of a 50° periodic saccade leads to uniform drug distribution in 30 s of simulation, the initial bolus site being left after 3 s of simulation. In absence of saccadic movements, the dominant transport contribution is the diffusive one and large molecules hardly reach their uniform distribution inside the vitreous cavity. A model describing the intravitreal distribution of large molecules in presence of saccades was developed, improving the understanding of drug transport mechanism after an intravitreal injection and highlighting how advection contribution enhances its distribution in the vitreous chamber.
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Laradji A, Shui YB, Karakocak BB, Evans L, Hamilton P, Ravi N. Bioinspired Thermosensitive Hydrogel as a Vitreous Substitute: Synthesis, Properties, and Progress of Animal Studies. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E1337. [PMID: 32183465 PMCID: PMC7143394 DOI: 10.3390/ma13061337] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/26/2020] [Accepted: 03/13/2020] [Indexed: 11/16/2022]
Abstract
In many vitreal diseases, the surgeon removes the natural vitreous and replaces it with silicone oils, gases, or balanced salt solutions to fill the eyeball and hold the retina in position. However, these materials are often associated with complications and have properties that differ from natural vitreous. Herein, we report an extension of our previous work on the synthesis of a biomimetic hydrogel that is composed of thiolated gellan as an analogue of type II collagen and poly(methacrylamide-co-methacrylate-co-bis(methacryloyl)cystamine), a polyelectrolyte, as an analogue of hyaluronic acid. This thermosensitive hydrogel can be injected into the eye as a viscous solution at 45 °C. It then forms a physical gel in situ when it reaches body temperature, and later forms disulfide covalent crosslinks. In this article, we evaluated two different formulations of the biomimetic hydrogels for their physical, mechanical, and optical properties, and we determined their biocompatibility with several cell lines. Finally, we report on the progress of the four-month preclinical evaluation of our bio-inspired vitreous substitute in comparison to silicone oil or a balanced salt solution. We assessed the eyes with a slit-lamp examination, intraocular pressure measurements, electroretinography, and optical coherence tomography. Preliminary results are very encouraging for the continuing evaluation of our bio-inspired hydrogel in clinical trials.
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Affiliation(s)
- Amine Laradji
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
| | - Ying-Bo Shui
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
| | - Bedia Begum Karakocak
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
| | - Lynn Evans
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
| | - Paul Hamilton
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
| | - Nathan Ravi
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (Y.-B.S.); (B.B.K.); (L.E.); (P.H.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
- Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63110, USA
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Biomechanism of resistance to retinal injury in woodpecker’s eyes. SCIENCE CHINA-LIFE SCIENCES 2020; 63:592-598. [DOI: 10.1007/s11427-019-1664-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/01/2019] [Indexed: 10/24/2022]
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27
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Schuster J, Koulov A, Mahler HC, Detampel P, Huwyler J, Singh S, Mathaes R. In Vivo Stability of Therapeutic Proteins. Pharm Res 2020; 37:23. [DOI: 10.1007/s11095-019-2689-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/16/2019] [Indexed: 01/05/2023]
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Khanna A, Jain MA, Narendran V. Retinal injury following intravitreal injection of a dexamethasone implant in a non-vitrectimised eye. Indian J Ophthalmol 2020; 68:1178. [PMID: 32461468 PMCID: PMC7508110 DOI: 10.4103/ijo.ijo_1618_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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29
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Ankamah E, Sebag J, Ng E, Nolan JM. Vitreous Antioxidants, Degeneration, and Vitreo-Retinopathy: Exploring the Links. Antioxidants (Basel) 2019; 9:antiox9010007. [PMID: 31861871 PMCID: PMC7022282 DOI: 10.3390/antiox9010007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/05/2019] [Accepted: 12/16/2019] [Indexed: 02/06/2023] Open
Abstract
The transparent vitreous body, which occupies about 80% of the eye’s volume, is laden with numerous enzymatic and non-enzymatic antioxidants that could protect the eye from oxidative stress and disease. Aging is associated with degeneration of vitreous structure as well as a reduction in its antioxidant capacity. A growing body of evidence suggests these age-related changes may be the precursor of numerous oxidative stress-induced vitreo-retinopathies, including vision degrading myodesopsia, the clinically significant entoptic phenomena that can result from advanced vitreous degeneration. Adequate intravitreal antioxidant levels may be protective against vitreous degeneration, possibly preventing and even improving vision degrading myodesopsia as well as mitigating various other vitreo-retinopathies. The present article is, therefore, a review of the different antioxidant molecules within vitreous and the inter-relationships between vitreous antioxidant capacity and degeneration.
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Affiliation(s)
- Emmanuel Ankamah
- Nutrition Research Centre Ireland, School of Health Science, Carriganore House, Waterford Institute of Technology, West Campus, Co., X91 K236 Waterford, Ireland;
- Institute of Eye Surgery, UPMC Whitfield, Buttlerstown, Co., X91 DH9W Waterford, Ireland
- Correspondence: (E.A.); (J.M.N.)
| | - J. Sebag
- VMR Consulting Inc., Huntington Beach, CA 92647, USA;
| | - Eugene Ng
- Nutrition Research Centre Ireland, School of Health Science, Carriganore House, Waterford Institute of Technology, West Campus, Co., X91 K236 Waterford, Ireland;
- Institute of Eye Surgery, UPMC Whitfield, Buttlerstown, Co., X91 DH9W Waterford, Ireland
| | - John M. Nolan
- Nutrition Research Centre Ireland, School of Health Science, Carriganore House, Waterford Institute of Technology, West Campus, Co., X91 K236 Waterford, Ireland;
- Correspondence: (E.A.); (J.M.N.)
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Crowell SR, Wang K, Famili A, Shatz W, Loyet KM, Chang V, Liu Y, Prabhu S, Kamath AV, Kelley RF. Influence of Charge, Hydrophobicity, and Size on Vitreous Pharmacokinetics of Large Molecules. Transl Vis Sci Technol 2019; 8:1. [PMID: 31695962 PMCID: PMC6827426 DOI: 10.1167/tvst.8.6.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 08/24/2019] [Indexed: 01/04/2023] Open
Abstract
Purpose Development of therapeutics for retinal disease with improved durability is hampered by inadequate understanding of pharmacokinetic (PK) drivers following intravitreal injection. Previous work shows that hydrodynamic radius is correlated with vitreal half-life over the range of 3 to 7 nm, and that charge and hydrophobicity influence systemic clearance. Better understanding the molecular attributes affecting vitreal elimination half-life enables improved design of therapeutics and enhances clinical translatability. Methods Impacts of charge and hydrophobicity on vitreal PK in the rabbit were systematically assessed using antibody and antibody fragment (Fab) variant series, including ranibizumab, altered through amino acid changes in hypervariable regions of the light chain. The impact of molecule size on vitreal PK was assessed in the rabbit, nonhuman primate, and human for a range of molecules (1–45 nm, net charge −1324 to +22.9 in rabbit), including published and internal data. Results No correlation was observed between vitreal PK and charge or hydrophobicity. Equivalent rabbit vitreal PK was observed for ranibizumab and its variants with isoelectric points (pI) in the range of 6.8 to 10.2, and hydrophobicities of the variable domain unit (FvHI) between 1009 and 1296; additional variant series had vitreal PK similarly unaffected by pI (5.4–10.2) and FvHI (1004–1358). Strong correlations were observed between vitreal half-life and hydrodynamic radius for preclinical species (R2 = 0.8794–0.9366). Conclusions Diffusive properties of soluble large molecules, as quantified by hydrodynamic radius, make a key contribution to vitreal elimination, whereas differences in charge or hydrophobicity make minor or negligible contributions. Translational Relevance These results support estimation of vitreal elimination rates based on molecular size in relevant preclinical species and humans.
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Affiliation(s)
- Susan R Crowell
- Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech, South San Francisco, CA, USA
| | - Kathryn Wang
- Drug Delivery, Genentech, South San Francisco, CA, USA
| | - Amin Famili
- Drug Delivery, Genentech, South San Francisco, CA, USA
| | - Whitney Shatz
- Protein Chemistry, Genentech, South San Francisco, CA, USA
| | - Kelly M Loyet
- Biochemical and Cellular Pharmacology, Genentech, South San Francisco, CA, USA
| | - Vincent Chang
- Bioanalytical Sciences, Genentech, South San Francisco, CA, USA
| | - Yanqiu Liu
- Bioanalytical Sciences, Genentech, South San Francisco, CA, USA
| | - Saileta Prabhu
- Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech, South San Francisco, CA, USA
| | - Amrita V Kamath
- Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech, South San Francisco, CA, USA
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31
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Kim Y, Roy S, Jung GY, Oh JS, Kim GW. Dual Optical Signal-based Intraocular Pressure-sensing Principle Using Pressure-sensitive Mechanoluminescent ZnS:Cu/PDMS Soft Composite. Sci Rep 2019; 9:15215. [PMID: 31645632 PMCID: PMC6811554 DOI: 10.1038/s41598-019-51771-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/08/2019] [Indexed: 11/21/2022] Open
Abstract
This paper presents a novel principle for intraocular pressure (IOP)-sensing (monitoring) based on a pressure-sensitive soft composite in which a dual optical signal is produced in response to impulsive pressure input. For the initial assessment of the new IOP sensing principle, a human eye is modeled as the spherically shaped shell structure filled with the pressurized fluid, including cornea, sclera, lens and zonular fiber, and a fluid-structure interaction (FSI) analysis was performed to determine the correlation between the internal pressure and deformation (i.e., strain) rate of the spherical shell structure filled with fluid by formulating the finite element model. The FSI analysis results for human eye model are experimentally validated using a proof-of-conceptual experimental model consisting of a pressurized spherical shell structure filled with fluid and a simple air-puff actuation system. In this study, a mechanoluminescent ZnS:Cu- polydimethylsiloxane (PDMS)-based soft composite is fabricated and used to generate the dual optical signal because mechanically driven ZnS:Cu/PDMS soft composite can emit strong luminescence, suitable for soft sensor applications. Similar to the corneal behavior of the human eye, inward and outward deformations occur on the soft composite attached to the spherical shell structure in response to air puffing, resulting in a dual optical signal in the mechnoluminescence (ML) soft composite.
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Affiliation(s)
- Yooil Kim
- Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, South Korea
| | - Sunanda Roy
- Department of Mechanical Engineering, Inha University, Incheon, 22212, South Korea
| | - Gwang-Yong Jung
- Department of Mechanical Engineering, Inha University, Incheon, 22212, South Korea
| | - Jung-Sik Oh
- Department of Naval Architecture and Ocean Engineering, Inha University, Incheon, 22212, South Korea
| | - Gi-Woo Kim
- Department of Mechanical Engineering, Inha University, Incheon, 22212, South Korea.
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Missel PJ, Sarangapani R. Physiologically based ocular pharmacokinetic modeling using computational methods. Drug Discov Today 2019; 24:1551-1563. [PMID: 31319151 DOI: 10.1016/j.drudis.2019.05.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 03/08/2019] [Accepted: 05/31/2019] [Indexed: 01/21/2023]
Abstract
By explicitly representing ocular anatomy, computational fluid dynamic simulation methods model drug mass transport both within and between ocular tissue regions, providing reliable animal-to-human translation of bioavailability. Here, we apply physiologically based models to simulate ocular drug administration. A non-anatomical model is used that applies a simple theorem for calculating ocular bioavailability from a topical dose. A computational fluid dynamic model is also described that incorporates ocular physiology in anatomical models for rabbit, monkey and man. This second method applies material properties and boundary conditions for various tissues enabling simulation of fluid flows, pressures, temperatures, convection, and drug advection following various modes of administration. The method provides a regional distribution with a given tissue not available using standard compartmental models, and enables translation of results from animal experiments into predictions for human ocular pharmacokinetics (PK).
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Affiliation(s)
- Paul J Missel
- Data Science and Digital Solutions, Alcon Vision LLC, Fort Worth, TX, USA.
| | - Ramesh Sarangapani
- Data Science and Digital Solutions, Alcon Vision LLC, Fort Worth, TX, USA
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Schulz A, Wahl S, Rickmann A, Ludwig J, Stanzel BV, von Briesen H, Szurman P. Age-Related Loss of Human Vitreal Viscoelasticity. Transl Vis Sci Technol 2019; 8:56. [PMID: 31293811 PMCID: PMC6602139 DOI: 10.1167/tvst.8.3.56] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/06/2019] [Indexed: 02/02/2023] Open
Abstract
Purpose To determine the viscoelasticity of human vitreous bodies and its changes with age in order to benefit the understanding and therapy of vitreoretinal diseases. Methods In a postmortem study, 190 human vitreous bodies were extracted from 33- to 92-year-old donors, analyzed with regard to their viscoelastic properties via dynamic mechanical analyses, and compared with bovine and porcine vitreous. Postmortem intervals and donor-related parameters were examined as potential parameters influencing vitreous viscoelasticity. Dynamic moduli of different hyaluronic acid (HA) solutions as well as human vitreous treated with HA injections were determined by frequency sweep tests. Results With age the viscoelasticity of human vitreous bodies decreased significantly and independently of postmortem intervals, diabetes, and the donor's sex. The storage modulus G′ and loss modulus G″ correlated strongly with the donor's age with r = −0.789 and r = −0.764, respectively. Bovine and porcine vitreous bodies exhibited dynamic moduli comparable only to the viscoelastic properties of aged human vitreous and are thus limited models for the simulation of the human vitreous. The viscoelasticity of aged human vitreous bodies was found to be increased after intravitreal injections of highly concentrated HA. Conclusions The present postmortem study is the first to show a significant age-related reduction in the viscoelasticity of entire human vitreous bodies. Highly concentrated HA injections may serve as a possible therapeutic approach for restoring the viscoelasticity of aged vitreous bodies. Translational Relevance These findings improve the understanding and therapy of the vitreous liquefaction with age and the associated vitreoretinal diseases.
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Affiliation(s)
- André Schulz
- Fraunhofer Institute for Biomedical Engineering, Sulzbach, Germany
| | - Silke Wahl
- Knappschaft Eye Clinic Sulzbach, Sulzbach, Germany
| | | | | | - Boris V Stanzel
- Fraunhofer Institute for Biomedical Engineering, Sulzbach, Germany.,Knappschaft Eye Clinic Sulzbach, Sulzbach, Germany
| | | | - Peter Szurman
- Knappschaft Eye Clinic Sulzbach, Sulzbach, Germany.,Centre for Ophthalmology, University Eye Hospital Tuebingen, Tuebingen, Germany
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Rangchian A, Francone A, Farajzadeh M, Hosseini H, Connelly K, Hubschman JP, Kavehpour HP. Effects of Collagenase Type II on Vitreous Humor—An In Situ Rheological Study. J Biomech Eng 2019; 141:2730407. [DOI: 10.1115/1.4043358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Indexed: 01/02/2023]
Abstract
The purpose of this study is to quantify the impact of enzyme activity on the vitreous humor structure over time to understand the mechanical characteristics of the vitreous humor gel. Changes in the mechanical behavior of the vitreous occur due to many reasons including aging, which may lead to many vitreoretinal diseases. The degeneration process of the vitreous has been studied; however, in situ experimental procedures to validate the existing hypotheses are limited. We examined thirty-eight porcine eyes using in situ rheological creep tests to measure the mechanical properties of the vitreous humor of the eyes prior to, 1 h and 24 h after the intravitreal injection. Eyes in one group were injected with collagenase type II solution and eyes in the control group were injected with phosphate buffered saline solution (PBS) with calcium and magnesium chloride. Prior to the injection, viscosity and creep compliance intercept values between both groups were not statistically different. At 1 h and 24 h after the injection, vitreous properties in the eyes from the first group showed a statistically significant increase in the J intercept values (representing the inverse of elasticity) compared to the control group. In addition, 1 h and 24 h after the injection, vitreous viscosity was lower in the eyes from the first group than in the eyes from the control group. These findings are a foundation for future studies on the effectiveness of intravitreal drugs that modify the mechanical properties of the vitreous humor.
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Affiliation(s)
- Aysan Rangchian
- Department of Bioengineering, Complex Fluid and Interfacial Physics Laboratory, University of California Los Angeles, Los Angeles, CA 90095-1597 e-mail:
| | - Anibal Francone
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA 90095 e-mail:
| | - Matthew Farajzadeh
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA 90095 e-mail:
| | - Helia Hosseini
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Tehran University of Medical Sciences, Tehran 1416753955, Iran e-mail:
| | - Kelly Connelly
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA 90095 e-mail:
| | - Jean-Pierre Hubschman
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA 90095 e-mail:
| | - H. Pirouz Kavehpour
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA 90095; Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095 e-mail:
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35
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Liu Z, Liow SS, Lai SL, Alli-Shaik A, Holder GE, Parikh BH, Krishnakumar S, Li Z, Tan MJ, Gunaratne J, Barathi VA, Hunziker W, Lakshminarayanan R, Tan CWT, Chee CK, Zhao P, Lingam G, Loh XJ, Su X. Retinal-detachment repair and vitreous-like-body reformation via a thermogelling polymer endotamponade. Nat Biomed Eng 2019; 3:598-610. [DOI: 10.1038/s41551-019-0382-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 03/05/2019] [Indexed: 12/31/2022]
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36
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Erratum: Rheological Properties and Age-Related Changes of the Human Vitreous Humor. Front Bioeng Biotechnol 2019; 7:44. [PMID: 30931302 PMCID: PMC6428972 DOI: 10.3389/fbioe.2019.00044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 11/22/2022] Open
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37
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Karimi A, Razaghi R, Sera T, Kudo S. A combination of the finite element analysis and experimental indentation via the cornea. J Mech Behav Biomed Mater 2019; 90:146-154. [DOI: 10.1016/j.jmbbm.2018.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 01/10/2023]
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38
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Tram NK, Swindle-Reilly KE. Rheological Properties and Age-Related Changes of the Human Vitreous Humor. Front Bioeng Biotechnol 2018; 6:199. [PMID: 30619846 PMCID: PMC6305337 DOI: 10.3389/fbioe.2018.00199] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/04/2018] [Indexed: 02/03/2023] Open
Abstract
The vitreous humor is a fragile, transparent hydrogel situated between the lens and the retina, occupying 80% of the eye's volume. Due to its viscoelastic behavior, the vitreous serves as a mechanical damper for the eye, absorbing impacts, and protecting the lens and retina. The vitreous liquefies with age, which compromises its function as a shock absorber and causes complications including retinal detachment, macular holes, and vitreous hemorrhage. Studies on the viscoelastic properties of the vitreous have been limited. Rheological testing of the vitreous has commonly been done on non-primate mammalian species. Human vitreous rheological properties have been previously reported; however, various measurement techniques were used, resulting in data that differed by orders of magnitude. Shear rheometry is commonly used to characterize soft tissues and hydrogels such as the vitreous humor. However, no human vitreous rheological data have been reported using this technique, preventing direct comparison to other published work. Additionally, no age-related changes in the mechanical properties of the human vitreous humor have been reported. Human vitreous samples (n = 39, aged 62 ± 15 years) were tested using a shear rheometer. Small amplitude oscillatory shear and creep experiments were performed. The linear viscoelastic region of the human vitreous was found to be below 1% strain. The solid phase of the old human vitreous was found to be stiffer than the young human vitreous and the porcine vitreous. The stiffness of the human vitreous gel also appeared to be positively correlated with age. Vitreous dehydration due to a decrease in hyaluronic acid concentration with age was proposed to cause the stiffening of the solid phase of the vitreous gel. Vitreous liquefaction, therefore, might be characterized as a simultaneous increase in liquid volume and localized stiffening of the vitreous gel. The phase separation of the vitreous humor with age has been hypothesized as the cause of many vitreous-related complications. This study provides viscoelastic properties and age-related changes of the human vitreous humor, which will aid in the design of biomimetic vitreous substitutes, enhancement in analyzing intravitreal transport of therapeutics, and understanding the pathological conditions of the vitreous humor.
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Affiliation(s)
- Nguyen K Tram
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Katelyn E Swindle-Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States.,William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, United States.,Department of Ophthalmology and Visual Science, The Ohio State University, Columbus, OH, United States
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Santhanam S, Shui YB, Struckhoff J, Karakocak BB, Hamilton PD, Harocopos GJ, Ravi N. Bioinspired Fibrillary Hydrogel with Controlled Swelling Behavior: Applicability as an Artificial Vitreous. ACS APPLIED BIO MATERIALS 2018; 2:70-80. [DOI: 10.1021/acsabm.8b00376] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sruthi Santhanam
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, United States
| | - Ying-Bo Shui
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Jessica Struckhoff
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Bedia Begum Karakocak
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, United States
| | - Paul D. Hamilton
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - George J. Harocopos
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, United States
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Nathan Ravi
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, United States
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, United States
- Department of
Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
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40
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A Combined Approach for the Analysis of Ocular Fluid Dynamics in the Presence of Saccadic Movements. Ann Biomed Eng 2018; 46:2091-2101. [DOI: 10.1007/s10439-018-02110-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/27/2018] [Indexed: 01/04/2023]
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41
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Geng X, Liu X, Wei W, Wang Y, Wang L, Chen K, Huo H, Zhu Y, Fan Y. Mechanical Evaluation of Retinal Damage Associated With Blunt Craniomaxillofacial Trauma: A Simulation Analysis. Transl Vis Sci Technol 2018; 7:16. [PMID: 29888114 PMCID: PMC5991806 DOI: 10.1167/tvst.7.3.16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 04/16/2018] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To evaluate retinal damage as the result of craniomaxillofacial trauma and explain its pathogenic mechanism using finite element (FE) simulation. METHODS Computed tomography (CT) images of an adult man were obtained to construct a FE skull model. A FE skin model was built to cover the outer surface of the skull model. A previously validated FE right eye model was symmetrically copied to create a FE left eye model, and both eye models were assembled to the skull model. An orbital fat model was developed to fill the space between the eye models and the skull model. Simulations of a ball-shaped object striking the frontal bone, temporal bone, brow, and cheekbones were performed, and the resulting absorption of the impact energy, intraocular pressure (IOP), and strains on the macula and ora serrata were analyzed to evaluate retinal injuries. RESULTS Strain was concentrated in the macular regions (0.18 in average) of both eyes when the frontal bone was struck. The peak strain on the macula of the struck-side eye was higher than that of the other eye (>100%) when the temporal bone was struck, whereas there was little difference (<10%) between the two eyes when the brow and cheekbones were struck. Correlation analysis showed that the retinal strain time histories were highly correlated with the IOP time histories (r > 0.8 and P = 0.000 in all simulation cases). CONCLUSIONS The risk of retinal damage is variable in craniomaxillofacial trauma depending on the struck region, and the damage is highly related to IOP variation caused by indirect blunt eye trauma. TRANSLATIONAL RELEVANCE This finite element eye model allows us to evaluate and understand the indirect ocular injury mechanisms in craniomaxillofacial trauma for better clinical diagnosis and treatment.
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Affiliation(s)
- Xiaoqi Geng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Xiaoyu Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Wei Wei
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China
| | - Yawei Wang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Lizhen Wang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Kinon Chen
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Hongqiang Huo
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Yuanjie Zhu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
- National Research Center for Rehabilitation Technical Aids, Beijing, China
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Asahina Y, Tachi N, Asahina Y, Yoshimura K, Ueta Y, Hashimoto Y. Six-month postoperative outcomes of intraoperative OCT-guided surgical cystotomy for refractory cystoid macular edema in diabetic eyes. Clin Ophthalmol 2017; 11:2099-2105. [PMID: 29200823 PMCID: PMC5703175 DOI: 10.2147/opth.s150385] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose This study evaluated the outcomes of surgical cystotomy for recurrent diabetic cystoid macular edema (CME). Patients and methods We analyzed 20 eyes with a clinical diagnosis of diabetic retinopathy and refractory CME. Release of vitreoretinal adhesion, epiretinal membrane (ERM) and internal limiting membrane (ILM) peeling and cystotomy guided by intraoperative optical coherence tomography (iOCT) were performed in every patient. Pars plana vitrectomy was also performed in 17 patients, 11 of whom also underwent lensectomy and intraocular lens implantation. Central retinal thickness (CRT), central minimum macular thickness (CMMT), macular volume (MV) and best-corrected visual acuity (BCVA) were compared preoperatively and 1 and 6 months post surgery. Results CRT, CMMT and MV significantly improved 1 and 6 months post surgery in each group (P<0.01). Significant improvements in BCVA were only observed 6 months post surgery (P<0.01). No intra- or postoperative complications were observed in all patients. Conclusion CRT, CMMT, MV and BCVA significantly improved 6 months following surgical cystectomy. This implies that iOCT-guided cystotomy could be another treatment option for refractory CME in diabetic eyes.
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Affiliation(s)
- Yuichi Asahina
- Eye Center, Shinseikai Toyama Hospital, Imizu, Toyama, Japan
| | - Naoko Tachi
- Eye Center, Shinseikai Toyama Hospital, Imizu, Toyama, Japan
| | - Yumi Asahina
- Eye Center, Shinseikai Toyama Hospital, Imizu, Toyama, Japan
| | | | - Yoshiki Ueta
- Eye Center, Shinseikai Toyama Hospital, Imizu, Toyama, Japan
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PARS PLANA VITRECTOMY FOR DIABETIC MACULAR EDEMA: A Systematic Review, Meta-Analysis, and Synthesis of Safety Literature. Retina 2017; 37:886-895. [PMID: 27632713 DOI: 10.1097/iae.0000000000001280] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PURPOSE To assess the risk and benefit of pars plana vitrectomy for diabetic macular edema. METHODS The authors conducted a systematic literature review using PubMed, EMBASE, Web of Science, and Cochrane Central Database of Controlled Trials until September 2014. The population was patients with diabetic macular edema, intervention vitrectomy, comparator macular laser or observation, and efficacy outcome visual acuity and central retinal thickness. Safety outcomes were intraoperative and postoperative surgical complications. The efficacy meta-analysis included only randomized controlled trials. The safety analysis included prospective, retrospective, controlled, and uncontrolled studies. RESULTS Five studies were eligible for the efficacy meta-analysis (n = 127 eyes) and 40 for the safety analysis (n = 1,562 eyes). Combining follow-up intervals from 6 to 12 months, the meta-analysis found a nonsignificant 2 letter visual acuity difference favoring vitrectomy, and a significant 102 μm greater reduction in central retinal thickness favoring vitrectomy, but a post hoc subgroup analysis found that a 6-month central retinal thickness benefit reversed by 12 months. The most frequent complications were retinal break (7.1%), elevated intraocular pressure (5.2%), epiretinal membrane (3.3%), and vitreous hemorrhage (2.4%). Cataract developed in 68.6% of 121 phakic eyes. CONCLUSION Vitrectomy produces structural and functional improvements in select eyes with diabetic macular edema, but the visual gains are not significantly better than with laser or observation. No major safety concerns were identified.
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Lee SM, Jung JW, Park SW, Lee JE, Byon IS. Retinal injury following intravitreal injection of a dexamethasone implant in a vitrectomized eye. Int J Ophthalmol 2017; 10:1019-1020. [PMID: 28730100 DOI: 10.18240/ijo.2017.06.31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/05/2016] [Indexed: 12/16/2022] Open
Affiliation(s)
- Seung Min Lee
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan 50612, Korea.,Department of Ophthalmology, College of Medicine, Pusan National University, Yangsan 50612, Korea
| | - Jae Woo Jung
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan 50612, Korea.,Department of Ophthalmology, College of Medicine, Pusan National University, Yangsan 50612, Korea
| | - Sung Who Park
- Department of Ophthalmology, College of Medicine, Pusan National University, Yangsan 50612, Korea.,Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Korea
| | - Ji Eun Lee
- Department of Ophthalmology, College of Medicine, Pusan National University, Yangsan 50612, Korea.,Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Korea
| | - Ik Soo Byon
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan 50612, Korea.,Department of Ophthalmology, College of Medicine, Pusan National University, Yangsan 50612, Korea
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45
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Preliminary study of the safety and efficacy of medium-chain triglycerides for use as an intraocular tamponading agent in minipigs. Graefes Arch Clin Exp Ophthalmol 2017; 255:1593-1604. [DOI: 10.1007/s00417-017-3695-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/24/2017] [Accepted: 05/09/2017] [Indexed: 11/27/2022] Open
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Davis JT, Hamilton PD, Ravi N. Poly(acrylamide co-acrylic acid) for use as an in situ gelling vitreous substitute. J BIOACT COMPAT POL 2017. [DOI: 10.1177/0883911516688482] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Our objective is to improve on our previous work developing thiol-containing water-soluble copolyacrylamides that form hydrogels in situ for use as vitreous substitutes. In this study, we evaluate the incorporation of acrylic acid by varying the feed ratio of acrylic acid monomer from 0 to 40 mol% in combination with acrylamide, and bis-acryloylcystamine as the reversible cross-linker. After polymerization, the formed copolymer hydrogels were reduced with dithiothreitol to cleave the disulfide cross-linkers. Purified, lyophilized copolymers were made in a concentration range of 12.5–17.5 mg/mL (polymer in deionized water) and were gelled by oxidation. Chemical, physical, optical, and rheological characterizations along with in vitro biocompatibility studies were performed using thiazolyl blue and Electric Cell–substrate Impedance Sensing. Increasing the percentage of acrylic acid caused the polymer to gel at 12.5 mg/mL as opposed to 20 mg/mL without acrylic acid. Storage modulus values covered the range of natural vitreous (1–108 Pa). Biocompatibility testing in tissue culture with retinal pigment epithelial cells (ARPE-19) showed no toxicity at 10 mg/mL or less when compared to controls, higher concentrations. In contrast to our previously reported copolyacrylamide hydrogels, these hydrogels remain optically clear and gel at lower concentrations and have the potential for use as vitreous substitutes.
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Affiliation(s)
- Joshua T Davis
- VA St. Louis Health Care System–John Cochran Division, St. Louis, MO, USA
- Department of Ophthalmology and Visual Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Paul D Hamilton
- VA St. Louis Health Care System–John Cochran Division, St. Louis, MO, USA
- Department of Ophthalmology and Visual Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Nathan Ravi
- VA St. Louis Health Care System–John Cochran Division, St. Louis, MO, USA
- Department of Ophthalmology and Visual Science, Washington University in St. Louis, St. Louis, MO, USA
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Karimi A, Razaghi R, Navidbakhsh M, Sera T, Kudo S. Computing the influences of different Intraocular Pressures on the human eye components using computational fluid-structure interaction model. Technol Health Care 2017; 25:285-297. [DOI: 10.3233/thc-161280] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Alireza Karimi
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Reza Razaghi
- Basir Eye Health Research Center, Tehran 14186, Iran
| | - Mahdi Navidbakhsh
- Department of Biomechanics, Science and Research Branch, Islamic Azad University, Tehran 755/4515, Iran
| | - Toshihiro Sera
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Susumu Kudo
- Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
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Schnichels S, Schneider N, Hohenadl C, Hurst J, Schatz A, Januschowski K, Spitzer MS. Efficacy of two different thiol-modified crosslinked hyaluronate formulations as vitreous replacement compared to silicone oil in a model of retinal detachment. PLoS One 2017; 12:e0172895. [PMID: 28248989 PMCID: PMC5332068 DOI: 10.1371/journal.pone.0172895] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/10/2017] [Indexed: 01/28/2023] Open
Abstract
The efficacy of two novel artificial vitreous body substitutes (VBS) consisting of highly biocompatible thiolated cross-linked hyaluronic acid (HA)-based hydrogels in comparison to silicone oil in a model of retinal detachment was investigated. Pars plana vitrectomy (23G) was performed in the right eye of 24 pigmented rabbits. Retinal detachment of two quadrants was induced by creating a small retinotomy near the vascular arcade and injecting balanced salt solution (BSS) subretinally. The retina was reattached by injecting air, which was followed by increasing the infusion pressure, and the retinal tear was treated by endolaser photocoagulation. At the end of the procedure, the eye was filled either with 5000-cs silicone oil (after fluid air exchange) or the respective hydrogel (with two different viscosities). Follow-up examination included slit lamp examination, funduscopy, intraocular pressure measurements (IOP), optical coherence tomography (OCT) and electroretinogram (ERG) measurements. After a maximum follow-up of four weeks both eyes were removed, examined macroscopically, photographed, and prepared for histology. Of the eight rabbits that received silicone oil, seven (87.5%) developed a recurrent retinal detachment with pronounced proliferative vitreoretinopathy within the first two weeks after surgery. In contrast, in the hydrogel treated eyes, the retina stayed attached in the majority of the cases (73.3%). IOP and retinal morphology were normal as long as the retina remained re-attached. In conclusions, this model of retinal detachment, both thiolated crosslinked hyaluronate hydrogels showed superior efficacy when compared to silicone oil. These hydrogels have a promising potential as novel vitreous body substitutes.
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Affiliation(s)
- Sven Schnichels
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
| | - Nele Schneider
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
| | | | - José Hurst
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
| | - Andreas Schatz
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
| | - Kai Januschowski
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
| | - Martin S. Spitzer
- Centre of Ophthalmology, University Eye Hospital Tübingen, Tübingen, Germany
- Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, Hamburg, Germany
- * E-mail:
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Connelly K, Sharif-Kashani P, Farajzadeh M, Hubschman JP, Kavehpour HP. Creep compliance rheology with a probe-like cylindrical geometry. Biorheology 2017; 53:221-236. [PMID: 28222498 DOI: 10.3233/bir-16112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Rheology experiments have been performed on the vitreous humor, a soft gel that rests inside of the eye, to study its viscoelastic behavior and underlying macromolecular structure. A significant challenge for experimentalists is preserving the macromolecular structure when removing vitreous from in vivo conditions. OBJECTIVE We have developed a novel probe-like rheometer geometry that allows us to perform shear rheology experiments on the vitreous humor in situ. The aim of this study is to assess the feasibility of the probe geometry. METHODS Creep compliance responses of silicone oils, Xanthan gum solutions, and bovine and porcine vitreous humor were measured using the probe geometry and compared to measurements performed with standard geometries. RESULTS Viscosities calculated from the creep responses of silicone oils closely match between the probe and standard geometry. Viscosities and creep compliance values of Xanthan gum measurements achieve order of magnitude agreement between the probe and standard geometry. Significant differences are detected with the probe between bovine and porcine vitreous (p<0.001). CONCLUSIONS These results suggest the probe may feasibly measure viscosities of Newtonian fluids, and correctly detect differences in the creep response of complex fluids with varying viscoelastic behaviors.
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Affiliation(s)
- Kelly Connelly
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, CA, USA
| | - Pooria Sharif-Kashani
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, CA, USA
| | - Matt Farajzadeh
- Stein Eye Institute, Department of Ophthalmology, University of California Los Angeles, CA, USA
| | - Jean-Pierre Hubschman
- Stein Eye Institute, Department of Ophthalmology, University of California Los Angeles, CA, USA
| | - H Pirouz Kavehpour
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, CA, USA
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50
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Santhanam S, Liang J, Struckhoff J, Hamilton PD, Ravi N. Biomimetic hydrogel with tunable mechanical properties for vitreous substitutes. Acta Biomater 2016; 43:327-337. [PMID: 27481290 PMCID: PMC5787031 DOI: 10.1016/j.actbio.2016.07.051] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 07/11/2016] [Accepted: 07/29/2016] [Indexed: 11/15/2022]
Abstract
UNLABELLED The vitreous humor of the eye is a biological hydrogel principally composed of collagen fibers interspersed with hyaluronic acid. Certain pathological conditions necessitate its removal and replacement. Current substitutes, like silicone oils and perfluorocarbons, are not biomimetic and have known complications. In this study, we have developed an in situ forming two-component biomimetic hydrogel with tunable mechanical and osmotic properties. The components are gellan, an analogue of collagen, and poly(methacrylamide-co-methacrylate), an analogue of hyaluronic acid; both endowed with thiol side groups. We used response surface methodology to consider seventeen possible hydrogels to determine how each component affects the optical, mechanical, sol-gel transition temperature and swelling properties. The optical and physical properties of the hydrogels were similar to vitreous. The shear storage moduli ranged from 3 to 358Pa at 1Hz and sol-gel transition temperatures from 35.5 to 43°C. The hydrogel had the ability to remain swollen without degradation for four weeks in vitro. Three hydrogels were tested for biocompatibility on primary porcine retinal pigment epithelial cells, human retinal pigment epithelial cells, and fibroblast (3T3/NIH) cells, by electric cell-substrate impedance sensing system. The two-component hydrogels allowed for the tuning and optimizing of mechanical, swelling, and transition temperature to obtain three biocompatible hydrogels with properties similar to the vitreous. Future studies include testing of the optimized hydrogels in animal models for use as a long-term substitute, whose preliminary results are mentioned. STATEMENT OF SIGNIFICANCE Although hydrogels are researched as long-term vitreous substitute, none have advanced sufficiently to reach clinical application. Our work focuses on the development of a novel two component in situ forming hydrogel that bio-mimic the natural vitreous. Our thiol-containing copolymers can be injected as an aqueous solution into the vitreous cavity wherein, at physiological temperature, the rigid component will instantaneously form a physical gel imbedding the random coil copolymer. Upon subsequent oxidation, the two components will form disulfide cross-links and a stable reversible hydrogel capable of providing osmotic pressure to reattach the retina. It may be left in the eye permanently or easily removed by injection of a simple reducing agent to cleave the disulfide bonds, rather than surgery. This contribution is significant because it is expected to provide patients with a much better quality of life by improving surgical outcomes, creating much less post-operative burden, and reducing the need for secondary surgeries.
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Affiliation(s)
- Sruthi Santhanam
- Energy, Environmental and Chemical Engineering, Washington University in St Louis, MO, USA
| | - Jue Liang
- Department of Ophthalmology and Visual Science, Washington University School of Medicine, MO, USA
| | - Jessica Struckhoff
- Department of Ophthalmology and Visual Science, Washington University School of Medicine, MO, USA; Department of Veterans Affairs, St Louis Medical Center, St Louis, MO, USA
| | - Paul D Hamilton
- Department of Ophthalmology and Visual Science, Washington University School of Medicine, MO, USA
| | - Nathan Ravi
- Department of Ophthalmology and Visual Science, Washington University School of Medicine, MO, USA; Energy, Environmental and Chemical Engineering, Washington University in St Louis, MO, USA; Department of Veterans Affairs, St Louis Medical Center, St Louis, MO, USA.
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