A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neova...A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far.展开更多
The keratoprosthesis(KPro;artificial cornea)is a special refractive device to replace human cornea by using heterogeneous forming materials for the implantation into the damaged eyes in order to obtain a certain visio...The keratoprosthesis(KPro;artificial cornea)is a special refractive device to replace human cornea by using heterogeneous forming materials for the implantation into the damaged eyes in order to obtain a certain vision.The main problems of artificial cornea are the biocompatibility and stability of the tissue particularly in penetrating keratoplasty.The current studies of tissue-engineered scaffold materials through comprising composites of natural and synthetic biopolymers together have developed a new way to artificial cornea.Although a wide agreement that the long-term stability of these devices would be greatly improved by the presence of cornea cells,modification of keratoprosthesis to support cornea cells remains elusive.Most of the studies on corneal substrate materials and surface modification of composites have tried to improve the growth and biocompatibility of cornea cells which can not only reduce the stimulus of heterogeneous materials,but also more importantly continuous and stable cornea cells can prevent the destruction of collagenase.The necrosis of stroma and spontaneous extrusion of the device,allow for maintenance of a precorneal tear layer,and play the role of ensuring a good optical surface and resisting bacterial infection.As a result,improvement in corneal cells has been the main aim of several recent investigations;some effort has focused on biomaterial for its well biological properties such as promoting the growth of cornea cells.The purpose of this review is to summary the growth status of the corneal cells after the implantation of several artificial corneas.展开更多
Corneal transplantation is the most common surgical procedure amongst solid organ transplants with a high survival rate of 86% at 1-year post-grafting. This high success rate has been attributed to the immune privileg...Corneal transplantation is the most common surgical procedure amongst solid organ transplants with a high survival rate of 86% at 1-year post-grafting. This high success rate has been attributed to the immune privilege of the eye. However, mechanisms originally thought to promote immune privilege, such as the lack of antigen presenting cells and vessels in the cornea, are challenged by recent studies. Nevertheless, the immunological and physiological features of the cornea promoting a relatively weak alloimmune response is likely responsible for the high survival rate in "low-risk" settings. Furthermore, although corneal graft survival in "lowrisk" recipients is favourable, the prognosis in "high-risk" recipients for corneal graft is poor. In "high-risk" grafts, the process of indirect allorecognition is accelerated by the enhanced innate and adaptive immune responses due to pre-existing inflammation and neovascularization of the host bed. This leads to the irreversible rejection of the allograft and ultimately graft failure. Many therapeutic measures are being tested in pre-clinical and clinical studies to counter the immunological challenge of "high-risk" recipients. Despite the prevailing dogma, recent data suggest that tissue matching together with use of systemic immunosuppression may increase the likelihood of graft acceptance in "high-risk" recipients. However, immunosuppressive drugs are accompanied with intolerance/side effects and toxicity, and therefore, novel cell-based therapies are in development which target host immune cells and restore immune homeostasis without significant side effect of treatment. In addition, developments in regenerative medicinemay be able to solve both important short comings of allotransplantation:(1) graft rejection and ultimate graft failure; and(2) the lack of suitable donor corneas. The advances in technology and research indicate that wider therapeutic choices for patients may be available to address the worldwide problem of corneal blindness in both "low-risk" and "hi展开更多
Successful corneal solid tissue transplantation,beginning with penetrating keratoplasty(PKP),and evolving to include contemporary lamellar and endothelial keratoplasty,has been a tremendous advancement in the struggle...Successful corneal solid tissue transplantation,beginning with penetrating keratoplasty(PKP),and evolving to include contemporary lamellar and endothelial keratoplasty,has been a tremendous advancement in the struggle to combat corneal blindness.However,there remain patients with high-risk features predictive of transplant failure,for whom donor keratoplasty is not a viable option.Prosthetic corneas have therefore been developed in order to meet the needs of these patients.The Boston type I keratoprosthesis(BKPro)is the most widely used prosthetic cornea in the treatment of corneal blindness.In the years since the BKPro’s introduction,refinement of surgical technique and clinical management as well as improvements in prosthetic design have contributed to promising patient outcomes,particularly in the short term.As such,patients with keratoprosthesis implants continue to grow in number,and the indications for the BKPro have commensurately increased.However,risks of permanently blinding complications after implantation persist over all stages of follow-up.For the foreseeable future,the success of keratoprosthesis(KPro)implantation will continue to depend on refined patient selection,preoperative optimization,and incisive postoperative management.Here we explore indications,surgical technique and postoperative outcomes as well as several core tenants in the management of BKPro patients:limiting glaucomatous progression,controlling inflammation,and optimizing the ocular surface.The exquisite sensitivity of the BKPro-implanted eye to perturbations in any one of these areas showcases the intimate relationship between the prosthetic device and its surrounding environment.展开更多
Background Pretreatment with chemical agents could alter the surface chemistry of the silicone gel, which makes it suitable for epithelial migration onto its surface and thus enhances the cytobiocompatibility. This st...Background Pretreatment with chemical agents could alter the surface chemistry of the silicone gel, which makes it suitable for epithelial migration onto its surface and thus enhances the cytobiocompatibility. This study aimed to evaluate the biological response of the corneal stroma to porous silicone gel pretreated with different chemical agents in vivo. Methods The porous silicone gels were treated with a mixed acid solution containing 23.2% H2SO4 and 0.8% K2Cr207 for 10 or 15 minutes or with 30% H202 for 15 minutes. Discs （4 mm in diameter） were inserted into interlamellar stromal pockets of New Zealand white rabbits and followed up for a period of 3 months. Clinical evaluations such as corneal infiltration, edema and neovascularization were performed daily. At 3 months, the fibroplasias and collagen deposition were examined under light and scanning electron microscopy （SEM） and by immunohistochemical analysis. Results Pretreatment of the discs obviously decreased conjunctival congestion, discharge, cornea edema, and the extent of neovascularization. More fibroblasts migrated into the pretreated discs than into the control, and collagen was deposited, indicating that the biocompatibility of the corneal replacements was enhanced by the chemical pretreatments. From immunohistochemical analysis, Type I collagen deposition in the pretreated silicone discs was greater than in the control. Conclusions Chemical treatment of silicone gel is effective in decreasing rabbit corneal inflammation, encouraging fibroblast in-growth, and enhancing tissue compatibility. Pretreated gels show good biological stability when used as a skirt material in Keratoprosthesis （Kpros）.展开更多
AIM: To present results of the keratoprosthesis method used at The Filatov Institute of Eye Diseases and Tissue Therapy. ·METHODS: A retrospective case series analysis was used to describe the development of new ...AIM: To present results of the keratoprosthesis method used at The Filatov Institute of Eye Diseases and Tissue Therapy. ·METHODS: A retrospective case series analysis was used to describe the development of new types of keratoprostheses and methods of implantation as well as different ways of leukoma strengthening. ·RESULTS: Keratoprosthesis was performed in 1 060 eyes of 1 040 patients with leukomas of different etiology: burns, 725 eyes (68.4% ); trauma, 120 eyes (11.3% ); keratitis and ocular pemphigoid, 108 eyes (10.2% ); and bullous keratopathy, 107 eyes (10.1% ). Visual acuity before keratoprosthesis consisted of light perception in 962 eyes (92% ), and 98 eyes (8% ) had minimal visual acuity (1/200-1/50). Both eyes were blind (visual acuity less than 1/200) in 955 patients (91.8% ). The period of blindness varied from 1 to 52 years. As a result of keratoprosthesis, visual acuity of ≥1/200 was restored in 1 023 of 1 060 eyes (96.5%). Visual acuity of 20/200-20/20 was achieved in 716 eyes (67.5%). At the last follow-up visit visual acuity of ≥1/200 was preserved in 806 eyes (76%), visual acuity of 20/200-20/20 was measured in 583 of 1 060 eyes (55%) and good keratoprosthesis fixation in the cornea was achieved in 986 of 1 060 eyes (93%). The minimal follow-up was 12 months (range, 12 months to 37 years, median 5 years). · CONCLUSION: Our techniques of keratoprosthesis effectively restore vision in patients with leukomas that cannot be treated by optical corneal grafting.展开更多
AIM：To investigate whether hydroxyapatite（HAp）coating can improve keratoprosthesis（KPro）implant biointegration,ultimately to decrease the risk of implantassociated complications.METHODS：The modified titanium imp...AIM：To investigate whether hydroxyapatite（HAp）coating can improve keratoprosthesis（KPro）implant biointegration,ultimately to decrease the risk of implantassociated complications.METHODS：The modified titanium implant was designed and prepared for artificial cornea.The titanium implant was treated with sandblasting and hydroxyapatite coating by acid-base two-step method.Surface was analyzed by scanning electron microscopy（SEM）,KPro implants coated with HAp and KPro implant sandblasted were implanted in rabbits.Tissue adhesion to the implant was assessed and compared to an unmodified implant by histopathology（HE）,transmission electron microscopy（TEM）and SEM.RESULTS：SEM demonstrated successful deposition of HAp on titanium implant sandblasted（HA/SB-Ti）.The hydroxyapatite coatings caused enhancement of keratocyte proliferation compared with unmodified implant surfaces.HAp coating significantly increased adhesion forces.HAp coating of implants reduced the inflammatory response around the KPro implants in vivo.CONCLUSION：HAp-coated surfaces for use in titanium KPro implant greatly enhanced adherence of the titanium KPro implant in the rabbit cornea.展开更多
文摘A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far.
基金National Natural Science Foundation of China(No.50973082)
文摘The keratoprosthesis(KPro;artificial cornea)is a special refractive device to replace human cornea by using heterogeneous forming materials for the implantation into the damaged eyes in order to obtain a certain vision.The main problems of artificial cornea are the biocompatibility and stability of the tissue particularly in penetrating keratoplasty.The current studies of tissue-engineered scaffold materials through comprising composites of natural and synthetic biopolymers together have developed a new way to artificial cornea.Although a wide agreement that the long-term stability of these devices would be greatly improved by the presence of cornea cells,modification of keratoprosthesis to support cornea cells remains elusive.Most of the studies on corneal substrate materials and surface modification of composites have tried to improve the growth and biocompatibility of cornea cells which can not only reduce the stimulus of heterogeneous materials,but also more importantly continuous and stable cornea cells can prevent the destruction of collagenase.The necrosis of stroma and spontaneous extrusion of the device,allow for maintenance of a precorneal tear layer,and play the role of ensuring a good optical surface and resisting bacterial infection.As a result,improvement in corneal cells has been the main aim of several recent investigations;some effort has focused on biomaterial for its well biological properties such as promoting the growth of cornea cells.The purpose of this review is to summary the growth status of the corneal cells after the implantation of several artificial corneas.
基金Supported by Saving Sight in Grampian,Development Trust of University of Aberdeen,United KingdomAction Medical Research United Kingdom(grant SP4328)Link?ping University,Sweden
文摘Corneal transplantation is the most common surgical procedure amongst solid organ transplants with a high survival rate of 86% at 1-year post-grafting. This high success rate has been attributed to the immune privilege of the eye. However, mechanisms originally thought to promote immune privilege, such as the lack of antigen presenting cells and vessels in the cornea, are challenged by recent studies. Nevertheless, the immunological and physiological features of the cornea promoting a relatively weak alloimmune response is likely responsible for the high survival rate in "low-risk" settings. Furthermore, although corneal graft survival in "lowrisk" recipients is favourable, the prognosis in "high-risk" recipients for corneal graft is poor. In "high-risk" grafts, the process of indirect allorecognition is accelerated by the enhanced innate and adaptive immune responses due to pre-existing inflammation and neovascularization of the host bed. This leads to the irreversible rejection of the allograft and ultimately graft failure. Many therapeutic measures are being tested in pre-clinical and clinical studies to counter the immunological challenge of "high-risk" recipients. Despite the prevailing dogma, recent data suggest that tissue matching together with use of systemic immunosuppression may increase the likelihood of graft acceptance in "high-risk" recipients. However, immunosuppressive drugs are accompanied with intolerance/side effects and toxicity, and therefore, novel cell-based therapies are in development which target host immune cells and restore immune homeostasis without significant side effect of treatment. In addition, developments in regenerative medicinemay be able to solve both important short comings of allotransplantation:(1) graft rejection and ultimate graft failure; and(2) the lack of suitable donor corneas. The advances in technology and research indicate that wider therapeutic choices for patients may be available to address the worldwide problem of corneal blindness in both "low-risk" and "hi
文摘Successful corneal solid tissue transplantation,beginning with penetrating keratoplasty(PKP),and evolving to include contemporary lamellar and endothelial keratoplasty,has been a tremendous advancement in the struggle to combat corneal blindness.However,there remain patients with high-risk features predictive of transplant failure,for whom donor keratoplasty is not a viable option.Prosthetic corneas have therefore been developed in order to meet the needs of these patients.The Boston type I keratoprosthesis(BKPro)is the most widely used prosthetic cornea in the treatment of corneal blindness.In the years since the BKPro’s introduction,refinement of surgical technique and clinical management as well as improvements in prosthetic design have contributed to promising patient outcomes,particularly in the short term.As such,patients with keratoprosthesis implants continue to grow in number,and the indications for the BKPro have commensurately increased.However,risks of permanently blinding complications after implantation persist over all stages of follow-up.For the foreseeable future,the success of keratoprosthesis(KPro)implantation will continue to depend on refined patient selection,preoperative optimization,and incisive postoperative management.Here we explore indications,surgical technique and postoperative outcomes as well as several core tenants in the management of BKPro patients:limiting glaucomatous progression,controlling inflammation,and optimizing the ocular surface.The exquisite sensitivity of the BKPro-implanted eye to perturbations in any one of these areas showcases the intimate relationship between the prosthetic device and its surrounding environment.
基金This study was supported by grants from the National Natural Science Foundation of China （No. 39970779）, Ministry of Health （No. 98-2-158）, and Shandong Scientific and Technological Committee （No. 1999BBCJA3）.Acknowledgements： The authors thank Dr. Edward C. Mignot and Dr. Pamela Holt, Shandong University for assistance in editing the manuscript.
文摘Background Pretreatment with chemical agents could alter the surface chemistry of the silicone gel, which makes it suitable for epithelial migration onto its surface and thus enhances the cytobiocompatibility. This study aimed to evaluate the biological response of the corneal stroma to porous silicone gel pretreated with different chemical agents in vivo. Methods The porous silicone gels were treated with a mixed acid solution containing 23.2% H2SO4 and 0.8% K2Cr207 for 10 or 15 minutes or with 30% H202 for 15 minutes. Discs （4 mm in diameter） were inserted into interlamellar stromal pockets of New Zealand white rabbits and followed up for a period of 3 months. Clinical evaluations such as corneal infiltration, edema and neovascularization were performed daily. At 3 months, the fibroplasias and collagen deposition were examined under light and scanning electron microscopy （SEM） and by immunohistochemical analysis. Results Pretreatment of the discs obviously decreased conjunctival congestion, discharge, cornea edema, and the extent of neovascularization. More fibroblasts migrated into the pretreated discs than into the control, and collagen was deposited, indicating that the biocompatibility of the corneal replacements was enhanced by the chemical pretreatments. From immunohistochemical analysis, Type I collagen deposition in the pretreated silicone discs was greater than in the control. Conclusions Chemical treatment of silicone gel is effective in decreasing rabbit corneal inflammation, encouraging fibroblast in-growth, and enhancing tissue compatibility. Pretreated gels show good biological stability when used as a skirt material in Keratoprosthesis （Kpros）.
文摘AIM: To present results of the keratoprosthesis method used at The Filatov Institute of Eye Diseases and Tissue Therapy. ·METHODS: A retrospective case series analysis was used to describe the development of new types of keratoprostheses and methods of implantation as well as different ways of leukoma strengthening. ·RESULTS: Keratoprosthesis was performed in 1 060 eyes of 1 040 patients with leukomas of different etiology: burns, 725 eyes (68.4% ); trauma, 120 eyes (11.3% ); keratitis and ocular pemphigoid, 108 eyes (10.2% ); and bullous keratopathy, 107 eyes (10.1% ). Visual acuity before keratoprosthesis consisted of light perception in 962 eyes (92% ), and 98 eyes (8% ) had minimal visual acuity (1/200-1/50). Both eyes were blind (visual acuity less than 1/200) in 955 patients (91.8% ). The period of blindness varied from 1 to 52 years. As a result of keratoprosthesis, visual acuity of ≥1/200 was restored in 1 023 of 1 060 eyes (96.5%). Visual acuity of 20/200-20/20 was achieved in 716 eyes (67.5%). At the last follow-up visit visual acuity of ≥1/200 was preserved in 806 eyes (76%), visual acuity of 20/200-20/20 was measured in 583 of 1 060 eyes (55%) and good keratoprosthesis fixation in the cornea was achieved in 986 of 1 060 eyes (93%). The minimal follow-up was 12 months (range, 12 months to 37 years, median 5 years). · CONCLUSION: Our techniques of keratoprosthesis effectively restore vision in patients with leukomas that cannot be treated by optical corneal grafting.
基金Supported by National Stem Cell and Translational Medicine Key Project (No.2017YFA0103204)the National Natural Science Foundation Project (No.81670830)+2 种基金the Capital Clinical Key Project (No. Z161100000516012)the Military Logistics Technology Project (No.CWS13C057)the PLA General Hospital Transformation Medicine Project (No.2016TM-025)
文摘AIM：To investigate whether hydroxyapatite（HAp）coating can improve keratoprosthesis（KPro）implant biointegration,ultimately to decrease the risk of implantassociated complications.METHODS：The modified titanium implant was designed and prepared for artificial cornea.The titanium implant was treated with sandblasting and hydroxyapatite coating by acid-base two-step method.Surface was analyzed by scanning electron microscopy（SEM）,KPro implants coated with HAp and KPro implant sandblasted were implanted in rabbits.Tissue adhesion to the implant was assessed and compared to an unmodified implant by histopathology（HE）,transmission electron microscopy（TEM）and SEM.RESULTS：SEM demonstrated successful deposition of HAp on titanium implant sandblasted（HA/SB-Ti）.The hydroxyapatite coatings caused enhancement of keratocyte proliferation compared with unmodified implant surfaces.HAp coating significantly increased adhesion forces.HAp coating of implants reduced the inflammatory response around the KPro implants in vivo.CONCLUSION：HAp-coated surfaces for use in titanium KPro implant greatly enhanced adherence of the titanium KPro implant in the rabbit cornea.
