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Avadhanam V, Ingavle G, Zheng Y, Kumar S, Liu C, Sandeman S. Biomimetic bone-like composites as osteo-odonto-keratoprosthesis skirt substitutes. J Biomater Appl 2020; 35:1043-1060. [PMID: 33174770 PMCID: PMC7917574 DOI: 10.1177/0885328220972219] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Osteo-odonto-keratoprostheses, incorporating dental laminate material as an
anchoring skirt around a central poly(methyl methacrylate) (PMMA) optic, have
been used to replace the cornea for many years. However, there are many
intricacies associated with the use of autologous dental laminate material,
surgical complexity and skirt erosion. Tissue engineering approaches to bone
replacement may offer suitable alternatives in osteo-odonto-keratoprosthesis
(OOKP) surgery. In this study, a hydrogel polymer composite was investigated as
a synthetic substitute for the OOKP skirt. A novel high strength
interpenetrating network (IPN) hydrogel composite with nano-crystalline
hydroxyapatite (nHAp) coated poly (lactic-co-glycolic acid) PLGA microspheres
was created to mimic the alveo-dental lamina by employing agarose and
poly(ethylene glycol) diacrylate (PEGDA) polymers. The incorporation of nHAp
coated PLGA microspheres into the hybrid IPN network provide a micro-environment
similar to that of skeletal tissues and improve cellular response. Agarose was
used as a first network to encapsulate keratocytes/3T3 fibroblasts and PEGDA
(6000 Da) was used as a second network with varying concentrations (20 and 40 wt
%) to produce a strong and biocompatible scaffold. An increased concentration of
either agarose or PEG-DA and incorporation of nHAp coated PLGA microspheres led
to an increase in the elastic modulus. The IPN hydrogel combinations supported
the adhesion and proliferation of both fibroblast and ocular human keratocyte
cell types during in in-vitro testing. The cells endured the
encapsulation process into the IPN and remained viable at 1 week
post-encapsulation in the presence of nHAp coated microspheres. The material did
not induce significant production of inflammatory cytokine IL-6 in comparison to
a positive control (p < 0.05) indicating non-inflammatory
potential. The nHAp encapsulated composite IPN hydrogels are mechanically
strong, cell supportive, non-inflammatory materials supporting their development
as OOKP skirt substitutes using a new approach to dental laminate biomimicry in
the OOKP skirt material.
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Affiliation(s)
- Venkata Avadhanam
- Brighton and Sussex Medical School, Brighton, UK.,Bristol Eye Hospital, Bristol, UK
| | - Ganesh Ingavle
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.,Symbiosis Centre for Stem Cell Research, Symbiosis International University, Pune, India
| | - Yishan Zheng
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Sandeep Kumar
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Christopher Liu
- Brighton and Sussex Medical School, Brighton, UK.,Sussex Eye Hospital, Brighton, UK.,Tongdean Eye Clinic, Hove, UK
| | - Susan Sandeman
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
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Rahmani S, Kanavi MR, Javadi MA, Langroudi MM, Aski SA. Histopathologic Evaluation of Polymer Supports for Pintucci-type Keratoprostheses: An Animal Study. J Ophthalmic Vis Res 2019; 14:243-250. [PMID: 31660102 PMCID: PMC6815345 DOI: 10.18502/jovr.v14i3.4779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/28/2018] [Indexed: 11/30/2022] Open
Abstract
Purpose To report histopathological findings for different types of polymers proposed as support for a Pintucci-type keratoprosthesis. Methods Six polymers, including three types of polyesters (#1-3), one type of polytetrafluoroethylene (PTFE, #4), polyethylene (#5), and expanded polytetrafluoroethylene (ePTFE, #6) were evaluated. Four samples of each material were placed under the orbicularis oculi muscles of 12 rabbits. After five weeks, the samples were removed and evaluated histopathologically. Fibrovascular tissue ingrowths were investigated in terms of tissue penetration depth into the materials (graded as none, mild, moderate, and intense) and fibrovascular ingrowth area at the ultimate level of tissue penetrance. ImageJ software was used to calculate fibrovascular tissue area between the material fibers, and the mean area values were compared between the materials. Results Polyester materials #1 and #3 demonstrated intense fibrovascular tissue penetration with a large fibrovascular ingrowth area; no overt tissue ingrowth was observed into material #6. The mean area of penetrated fibrovascular tissues was significantly different between materials (P < 0.001). Materials #2, #4, and #5 showed moderate fibrovascular tissue ingrowth and the area of presented fibrovascular tissue at the paracentral parts of material #4 was significantly smaller than that of materials #1 (P = 0.02) and #3 (P = 0.01). Conclusion Two polyester materials that had relatively large pore sizes demonstrated a deep and large area of fibrovascular ingrowth. Given that material #3 is thicker and more consistent than material #1, the former can be used as the appropriate material for supporting the Pintucci-type keratoprosthesis.
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Affiliation(s)
- Saeed Rahmani
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Optometry, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mozhgan Rezaei Kanavi
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Javadi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Sasha Afsar Aski
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Li Z, Yam GHF, Thompson BC, Setiawan M, Goh GTW, Tan D, Mehta JS, Khor KA. Optimization of spark plasma sintered titania for potential application as a keratoprosthesis skirt. J Biomed Mater Res A 2017; 105:3502-3513. [PMID: 28869708 DOI: 10.1002/jbm.a.36198] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 08/02/2017] [Accepted: 08/30/2017] [Indexed: 11/11/2022]
Abstract
The manufacture of mechanically strong and biocompatible titania (TiO2 ) materials is of vital importance for their application as corneal implant skirts. This study was aimed at optimizing the selection of raw powder and sintering conditions for TiO2 ceramics. TiO2 compacts were synthesized from five raw powders, denoted as Altair, Inframat, Alfa, Materion, and Amperit, respectively, by spark plasma sintering using different sintering parameters. The XRD and Raman results confirmed that the anatase TiO2 phase in the Inframat powder had converted completely to rutile TiO2 phase after sintering at 900°C and above. The nanoindentation results indicated that among the five types of TiO2 samples sintered at 1100°C, the Inframat pellets possessed the highest Young's modulus and hardness. Additionally, when Materion samples were employed to study the effects of SPS parameters, a higher sintering temperature in the range of 1100-1300°C decreased the mechanical properties of sintered pellets probably due to the generation of more structural defects. Culture of human corneal stromal fibroblasts on the sintered sample surfaces showed that comparably high cell viability and proliferation were observed on all TiO2 samples except Amperit compared to positive control. Furthermore, cells cultured on Inframat TiO2 sintered in the temperature range of 900-1300°C exhibited viability and formation of focal adhesion complex similar to those on control, and those prepared at 1100°C had significantly higher cell proliferation indices than control. In conclusion, Inframat TiO2 consolidated at 1100°C by SPS was the best formulation for the preparation of mechanically strong and biocompatible Keratoprosthesis skirt. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3502-3513, 2017.
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Affiliation(s)
- Zhong Li
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Gary Hin-Fai Yam
- Singapore Eye Research Institute, 11 Third Hospital Ave, Singapore, 168751, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Brianna C Thompson
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Melina Setiawan
- Singapore Eye Research Institute, 11 Third Hospital Ave, Singapore, 168751, Singapore
| | | | - Donald Tan
- Singapore Eye Research Institute, 11 Third Hospital Ave, Singapore, 168751, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore.,Singapore National Eye Centre, 11 Third Hospital Ave, Singapore, 168751, Singapore
| | - Jodhbir S Mehta
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.,Singapore Eye Research Institute, 11 Third Hospital Ave, Singapore, 168751, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, Singapore, 169857, Singapore.,Singapore National Eye Centre, 11 Third Hospital Ave, Singapore, 168751, Singapore
| | - Khiam Aik Khor
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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Sevgi DD, Fukuoka H, Afshari NA. 20 Years of Advances in Keratoprosthesis. CURRENT OPHTHALMOLOGY REPORTS 2016. [DOI: 10.1007/s40135-016-0107-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zarei-Ghanavati S, Betancurt C, Mas AM, Wang J, Perez VL. Ultra high resolution optical coherence tomography in Boston type I keratoprosthesis. J Ophthalmic Vis Res 2015; 10:26-32. [PMID: 26005549 PMCID: PMC4424714 DOI: 10.4103/2008-322x.156092] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/26/2013] [Indexed: 11/19/2022] Open
Abstract
Purpose: To evaluate the anterior keratoprosthesis-cornea interface in eyes with Boston type I keratoprosthesis (Kpro). Methods: In a prospective non-interventional study, patients with Boston type I Kpro underwent ultra-high resolution optical coherence tomography (UHR-OCT) evaluation. The images were used to measure and describe characteristics of the anterior keratoprosthesis-cornea interface, epithelial interaction at the keratoprosthesis edge and the keratoprosthesis-cornea interface gap. Results: Ten patients including 4 male and 6 female subjects with different preoperative diagnoses, i.e. 8 multiple corneal graft failures and 2 immunological ocular surface diseases, were studied. Mean age was 62.1 ± 20.0 (range, 33.0-83.0) years and mean interval between surgery and UHR-OCT evaluation was 15.2 ± 11.09 months. In eight patients, 360° epithelial growth over the peripheral edge of the Kpro was documented. We detected keratoprosthesis-cornea interface gap in three patients. One subject had developed postoperative endophthalmitis 8 months after surgery and the other two cases were among the high risk group according to the preoperative diagnosis. In one patient with severe ocular hypotony, the Kpro edge was inserted into the anterior stroma and covered with epithelium. Conclusion: UHR-OCT showed that corneal epithelium covers the Kpro edge and seals the potential space between the Kpro and cornea in 80% of cases. The presence of a gap in the interface and lack of epithelial sealing around the Kpro edge might be associated with endophthalmitis.
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Affiliation(s)
| | | | | | - Jianhua Wang
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Victor L Perez
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
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Al Arfaj K. Boston keratoprosthesis - Clinical outcomes with wider geographic use and expanding indications - A systematic review. Saudi J Ophthalmol 2015; 29:212-21. [PMID: 26155082 PMCID: PMC4487949 DOI: 10.1016/j.sjopt.2015.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 12/24/2014] [Accepted: 02/02/2015] [Indexed: 11/13/2022] Open
Abstract
Over 2 decades of research, several design modifications, and improvements in post-operative management have made Boston keratoprosthesis (B-KPro) a viable option for patients with corneal blindness for whom traditional keratoplasty procedure has a very low probability of success. In this systematic review, we examined the indications, visual outcomes, complications and retention rate of the literature published in the past 10 years (2005–2014). While most of the studies report smaller datasets (typically <50 eyes), some of the recent multicenter studies have reported large datasets (up to 300 eyes). Most of the literature is published from the US; however, last few years have witnessed some papers reporting the successful use of B-Kpro from developing countries or arid climatic conditions (such as the Kingdom of Saudi Arabia). Due to differences in the causes of corneal blindness in different geographic regions, newer indications for B-Kpro are emerging (e.g. trachoma). Additionally, improving clinical outcomes and increasing surgeon confidence have also expanded indications to include cases of unilateral visual impairment and paediatric age. We observed that there is growing body of evidence of successful clinical use of B-KPro; however, financial challenges, lack of trained surgeons, shortage of donor corneas must be overcome to improve accessibility of B-KPro.
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Affiliation(s)
- Khalid Al Arfaj
- Department of ophthalmology, Dammam University, Postal code 40033, King Fahad University Hospital, Alkhobar, Saudi Arabia
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Improving Boston type 1 keratoprosthesis procedure: one-touch femtosecond-assisted preparation and centration of donor carrier tissue. Eur J Ophthalmol 2013; 24:191-5. [PMID: 24338585 DOI: 10.5301/ejo.5000387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE We describe a technique to avoid decentration of the visual axis of the Boston type 1 keratoprosthesis (Kpro), performing 2 concentric trephinations with femtosecond laser. METHODS Two concentric side cuts were performed in a donor cornea using the 150-kHz Intralase FS laser. Within the same applanation procedure, an 8.5-mm-diameter anterior side cut was performed, followed by a concentric 3-mm-diameter anterior side cut. RESULTS The technique was successfully replicated in 7 cases. CONCLUSIONS Femtosecond laser-assisted double trephination results in a correctly prepared donor cornea, and in an inner side precisely matched with the prosthesis. At the end of the surgery, the Kpro was correctly centered.
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Wilson-Miller R, Stanley H. The psychosocial needs of patients undergoing ocular-odonto-kerato-prosthesis (OOKP) surgery: a nurse perspective. ACTA ACUST UNITED AC 2013. [DOI: 10.12968/ijop.2013.4.4.163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Helen Stanley
- Head of the Centre for Academic and Practice Development and Director of the Graduate Programme in Health and Social Sciences. School of Nursing and Midwifery, University of Brighton, UK
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Huhtinen R, Sandeman S, Rose S, Fok E, Howell C, Fröberg L, Moritz N, Hupa L, Lloyd A. Examining porous bio-active glass as a potential osteo-odonto-keratoprosthetic skirt material. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2013; 24:1217-1227. [PMID: 23386212 DOI: 10.1007/s10856-013-4881-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 01/28/2013] [Indexed: 06/01/2023]
Abstract
Bio-active glass has been developed for use as a bone substitute with strong osteo-inductive capacity and the ability to form strong bonds with soft and hard tissue. The ability of this material to enhance tissue in-growth suggests its potential use as a substitute for the dental laminate of an osteo-odonto-keratoprosthesis. A preliminary in vitro investigation of porous bio-active glass as an OOKP skirt material was carried out. Porous glass structures were manufactured from bio-active glasses 1-98 and 28-04 containing varying oxide formulation (1-98, 28-04) and particle size range (250-315 μm for 1-98 and 28-04a, 315-500 μm for 28-04b). Dissolution of the porous glass structure and its effect on pH was measured. Structural 2D and 3D analysis of porous structures were performed. Cell culture experiments were carried out to study keratocyte adhesion and the inflammatory response induced by the porous glass materials. The dissolution results suggested that the porous structure made out of 1-98 dissolves faster than the structures made from glass 28-04. pH experiments showed that the dissolution of the porous glass increased the pH of the surrounding solution. The cell culture results showed that keratocytes adhered onto the surface of each of the porous glass structures, but cell adhesion and spreading was greatest for the 98a bio-glass. Cytokine production by all porous glass samples was similar to that of the negative control indicating that the glasses do not induce a cytokine driven inflammatory response. Cell culture results support the potential use of synthetic porous bio-glass as an OOKP skirt material in terms of limited inflammatory potential and capacity to induce and support tissue ingrowth.
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Affiliation(s)
- Reeta Huhtinen
- BioCity Turku Biomaterials Research Program, Institute of Dentistry, Turku Clinical Biomaterials Centre-TCBC, University of Turku, Turku, Finland
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Langenbucher A, Szentmáry N, Speck A, Seitz B, Eppig T. Calculation of power and field of view of keratoprostheses. Ophthalmic Physiol Opt 2013; 33:412-9. [DOI: 10.1111/opo.12046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 02/08/2013] [Indexed: 11/28/2022]
Affiliation(s)
| | - Nóra Szentmáry
- Department of Ophthalmology and University Eye Clinic; Saarland University Medical Center; Homburg/Saar; Germany
| | - Alexis Speck
- Experimental Ophthalmology; Saarland University; Homburg/Saar; Germany
| | - Berthold Seitz
- Department of Ophthalmology and University Eye Clinic; Saarland University Medical Center; Homburg/Saar; Germany
| | - Timo Eppig
- Experimental Ophthalmology; Saarland University; Homburg/Saar; Germany
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de Araujo AL, Charoenrook V, de la Paz MF, Temprano J, Barraquer RI, Michael R. The role of visual evoked potential and electroretinography in the preoperative assessment of osteo-keratoprosthesis or osteo-odonto-keratoprosthesis surgery. Acta Ophthalmol 2012; 90:519-25. [PMID: 21595859 DOI: 10.1111/j.1755-3768.2010.02086.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To determine the value of electroretinography (ERG) and visual evoked potential (VEP) in predicting visual outcome in patients undergoing osteo-keratoprosthesis (OKP) or osteo-odonto-keratoprosthesis (OOKP) surgery. METHODS We performed a retrospective cohort study of 143 eyes in 101 patients who underwent OKP or OOKP surgery. The subjects underwent ERG, VEP testing or both up to 6 months prior to surgery. The ERG and VEP results were classified into four categories based on wave amplitude, latency and configuration. The main outcome was the maximum best-corrected visual acuity (maxBCVA) reached at any time postoperatively. RESULTS One hundred thirty-four cases had undergone preoperative ERG, 82 VEP and 73 both examinations. The sensitivities of ERG and VEP to detect maxBCVA≥0.05 were 68.5% and 87%, respectively, while the specificity was 63.2% for ERG and 47.4% for VEP. The maxBCVA was significantly better in patients with normal ERG (p=0.033) and those with normal VEP (p=0.048), once having defined appropriate normal and abnormal cut-off levels. When comparing fellow eyes in patients who underwent surgery in both eyes, maxBCVA was better in the eyes that had better VEP results (p=0.013). CONCLUSION Eyes demonstrating normal ERG or VEP achieved better visual outcome than those with abnormal results. In addition, VEP proved instrumental in determining the eye with the best prognosis when comparing both eyes of a given patient.
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Affiliation(s)
- Aline L de Araujo
- Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain
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Abstract
Biointegration refers to the interconnection between a biomedical device and the recipient tissue. In many implant devices, the lack of proper biointegration can cause device failure and potentially serious medical problems. This review summarizes the recent progress in surface chemistry, drug delivery and antifouling methods to improve the biointegration of implants. Much progress has been made as our understanding of biological systems and material properties expands and as new technologies become available. This article addresses methods of enhancing biointegration by means of modifying implant surface chemistry and by drug-delivery approaches.
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Tan XW, Lakshminarayanan R, Liu SP, Goh E, Tan D, Beuerman RW, Mehta JS. Dual functionalization of titanium with vascular endothelial growth factor and β-defensin analog for potential application in keratoprosthesis. J Biomed Mater Res B Appl Biomater 2012; 100:2090-100. [DOI: 10.1002/jbm.b.32774] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 04/16/2012] [Accepted: 06/03/2012] [Indexed: 01/12/2023]
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Yang C, Wang Y, Chen X. Preparation and evaluation of biomimetric nano-hydroxyapatite-based composite scaffolds for bone-tissue engineering. CHINESE SCIENCE BULLETIN 2012. [DOI: 10.1007/s11434-012-5201-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Surface epithelialization of the type I Boston keratoprosthesis front plate: immunohistochemical and high-definition optical coherence tomography characterization. Graefes Arch Clin Exp Ophthalmol 2012; 250:1195-9. [PMID: 22371021 PMCID: PMC3404271 DOI: 10.1007/s00417-012-1960-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/27/2012] [Accepted: 01/31/2012] [Indexed: 11/25/2022] Open
Abstract
Background The aim of this work is to characterize a transparent tissue layer partially covering the anterior surface of the type I Boston permanent keratoprosthesis front plate in four patients. Methods The tissue over the front plate was easily scrolled back as a single transparent layer using a sponge. In two cases, histopathologic analysis was undertaken and immunofluorescent staining with a cytokeratin 3-specific antibody was performed. The relationship of the tissue to the keratoprosthesis device was further characterized using spectral domain high-definition optical coherence tomography (HD-OCT). Results Histopathologic analysis revealed the tissue to be non-keratinized squamous epithelium. No goblet cells were seen, suggesting the cells were of corneal, and not conjunctival, epithelial origin. Immunofluorescent staining of all cells was positive for cytokeratin 3, a protein strongly associated with corneal epithelium. The tissue was easily discerned by HD-OCT and was of substantial thickness near the external junction between the keratoprosthesis device and the carrier corneal tissue. In three cases, visual acuity was unaffected by the presence or absence of this tissue. In one case, a prominent tissue margin temporarily obscured the visual axis and reduced visual acuity; this resolved with mechanical central debridement and has not recurred. Conclusions The transparent tissue layer covering the anterior surface of the type I Boston keratoprosthesis front plate was found to represent non-keratinized squamous epithelium, most likely of corneal epithelial origin. This potentially represents a further step in bio-integration of the keratoprosthesis device. In particular, epithelial coverage of the critical junction between the device and the carrier corneal tissue might serve an important barrier function and further reduce the incidence of infection and extrusion of the type I Boston permanent keratoprosthesis.
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Abstract
Glaucoma drainage devices are more frequently being used for glaucoma filtering surgeries, even those at low risk for failure with trabeculectomy. There are 4 major devices available: the Molteno, Baerveldt, Krupin, and Ahmed. The Molteno and Baerveldt are non-valved implants, while the Krupin and Ahmed are valved. The success rates of the different valves are about equal at approximately 70% with a mean intraocular pressure (IOP) lowering of at least 50% from the pre-operative IOP. Unfortunately, the failure rate is about 10% per year, leading to only 50% functional drainage devices at 5 years. Therefore, research on the biomaterials, shape, and technique of drainage implant surgery is being done in hopes of increasing long term success rates.
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Affiliation(s)
- Shuchi Patel
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Glaucoma Service, Harvard Medical School, Cambridge, MA, USA.
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