The historical development and an overview of contemporary keratoprostheses

Corneal blindness is a major cause of ocular morbidity that affects 4.5 million people worldwide. Though penetrating keratoplasty is an excellent option for most patients with corneal blindness, there are various conditions for which corneal transplantation carries a low likelihood of success. In cases of multiple failed transplants, the keratoprosthesis, an artificial cornea, is a well-documented surgical option, though few models are commercially available. Keratoprostheses also provide a solution to those in developing areas of the world who do not have access to penetrating keratoplasty owing to limitations in the supply of corneal donor tissue. We summarize the history of keratoprostheses, examine the various keratoprosthesis models used across the globe, and highlight efforts to improve the accessibility and biointegration of keratoprosthesis through novel technological developments.     

Binocular vision recovery in bilateral keratoplasty.

PURPOSE: To determine the benefit of bilateral penetrating keratoplasty with regard to binocular vision. METHODS: We compared patients who underwent corneal transplantation bilaterally with patients who had successful corneal transplantation in one eye and corneal disease in the other eye. Specifically, changes in fusion, stereopsis, and binocular vision function were analyzed. A questionnaire regarding performance of daily tasks was given. RESULTS: Patients with bilateral keratoplasty performed better in all the analyzed functions. Fusion was achieved by 81.25% in the unilateral group versus 100% in the bilateral group (p = 0.15). Stereopsis was present more in the bilateral group (100% vs. 62.5%, p = 0.008) and the quantity of stereopsis was significantly better in the bilateral group (121 seconds of arc vs. 1,284 seconds of arc, p = 0.014). 88.8% of the patients subjectively improved in daily activities after second eye surgery. CONCLUSION: There are objective and subjective improvements after bilateral penetrating keratoplasty.     

Corneal and conjunctival toxicity from hydrogen peroxide: a patient with chronic self-induced injury

PURPOSE: To report a patient with severe corneal and conjunctival toxicity from long-term, habitual use of hydrogen peroxide as an eye wash. DESIGN: Observational case report. INTERVENTION AND TESTING: Serial examinations of the cornea, conjunctiva, and ocular adnexa were done. Penetrating keratoplasty with amniotic membrane transplantation was performed. MAIN OUTCOME MEASURES: Ocular inflammation, pain, and visual acuity outcome. RESULTS: Bilateral corneal and conjunctival inflammation and scarring mimicking ocular-cicatricial pemphigoid were noted. Formation of a descemetocele after starting treatment with low-dose topical steroids required emergent penetrating keratoplasty with amniotic membrane transplantation. CONCLUSIONS: This is the first reported case of ocular surface toxicity in a patient after deliberate chronic use of high-dose hydrogen peroxide. It highlights the value of obtaining a thorough medical and social history and the importance of direct questioning about the use of any medications or agents on the eyes before making a diagnosis or initiating therapy.     

分期实施异体角膜缘干细胞移植与穿透性角膜移植术治疗严重化学伤(英文)

有1位于1996年实施右眼穿透性角膜移植术失败的双眼严重眼表化学伤的患者, 62岁,右眼视力手动,左眼视力光感。于2006-09-16/2007-02-07分别对右眼实施了异体角膜缘干细胞移植术和穿透性角膜移植术,经过术后5m的药物治疗观察,最终获得了右眼最佳矫正视力为6/30,角膜移植片透明,眼表得以重建,并未发现明显排斥迹象的良好效果。     

角膜移植治疗角膜及眼表疾病98例临床分析

目的分析穿透性角膜移植及板层角膜移植治疗角膜疾病及眼表疾病的临床特点。方法回顾性研究穿透性角膜移植、板层角膜移植及板层角膜移植联合羊膜移植手术共98例（101眼）,观察术后视力、排斥反应、继发青光眼及原发病复发。随访6～24月,平均12．8月。结果穿透性角膜移植术79例（82眼）巾,62例（78．48％）术后视力较术前有提高,排斥反应11例（12眼）,原发病复发3例（3眼）,继发青光眼10例（10眼）。板层角膜移植术后视力无明显变化,排斥反应1例（1眼）,未见原发病复发及继发青光眼。结论角膜移植是治疗严重角膜疾病及眼表疾病有效手术方式,积极预防及治疗术后并发症可以提高角膜移植成功率。     

角膜移植的研究进展

角膜移植是用透明、健康的供体角膜组织替换混浊病变的角膜组织,使患者复明或控制角膜病变,达到增进视力或治疗某些角膜疾病的眼科治疗方法.传统角膜移植分为穿透性角膜移植和板层角膜移植.近10a,深板层角膜移植和内皮细胞移植手术逐渐崛起.而目前,人工角膜移植手术的发展为不适合传统穿透性角膜移植手术的患者提供一种新的选择.本文综述了目前角膜移植领域手术技术的适应证、术后并发症等.     

A tectonic keratoprosthesis using expanded polytetrafluoroethylene as a supporting skirt in humans.

A tectonic keratoplasty was performed with a keratoprosthesis using expanded polytetrafluoroethylene as a supporting skirt, on the left eye of a 23-year-old woman who needed an emergency corneal transplantation due to corneal perforation. The keratoprosthesis implanted, consisted of a supporting skirt which was made of expanded polytetrafluoroethylene (PTFE), and an optic portion which was made of polymethylmethacrylate (PMMA). The optic portion and the supporting skirt were attached by cyanoacrylate tissue adhesive (Histoacryl). Two months post-operatively, the keratoprosthesis was extruded, leaving an opacified, vascularized cornea. A penetrating keratoplasty was performed 1 month later. The excised cornea was composed of granulation tissue. To our knowledge, this is the first case of tectonic keratoprosthesis using expanded PTFE as a supporting skirt in humans.     

Storage, surgery, outcome, complications, and new developments in corneal and conjunctival grafts

This review covers last year's literature on corneal, limbal, and conjunctival transplantation including tissue storage and eye banking. In this area, the main themes were related to a better evaluation of tissue viability and the exclusion of disease transmission. An analysis of the changing indications for penetrating keratoplasty shows the differences between American and European series. Most efforts in relation to surgical techniques are oriented toward obtaining better refractive results, whereas the study of large series sheds new light on the risk factors for graft failure and other complications. Limbal transplants have acquired the status of a new field in the surgical treatment of ocular surface disease, particularly in relation to corneal stem cell deficiencies.     

联合或不联合板层角膜移植的结膜瓣移植治疗巩膜坏死

目的介绍结膜瓣移植治疗眼部烧伤和眼科手术后巩膜缺血坏死的手术方法,观察其临床疗效。方法回顾性病例研究。2007年1月至2012年3月,共13例眼部烧伤和眼科手术后巩膜缺血坏死、溶解的患者在山东省眼科医院接受了结膜瓣移植,其中碱烧伤4例．热烧伤6例．翼状胬肉切除手术后巩膜坏死3例。对所有患者行带蒂结膜瓣转位或游离结膜瓣移植术治疗,其中4例行单纯结膜瓣移植,2例联合部分板层角膜移植（LK）术,6例联合羊膜移植（AMT）术,1例联合LK和AMT术。随诊3—24个月,对手术后巩膜坏死和结膜瓣存活等情况进行观察。结果移植的结膜瓣1周内血运差、色苍白,1周后逐渐出现充血表现,2周拆除结膜瓣缝线后充血症状逐渐减轻。13例患者结膜瓣均愈合良好,巩膜坏死控制。至最后一次随访,2例角膜透明,3例角膜植片透明,1例角膜斑翳．7例角膜血管化。结论结膜瓣移植（或联合LK和AMT）治疗眼部烧伤和眼科手术后巩膜坏死在临床上安全有效,能够较好地解决巩膜穿孔的风险,为后续治疗提供一个相对稳定的眼部环境。     

眼前后段联合手术治疗复杂性眼病的远期疗效评价

目的 探讨临时人工角膜下行前后段联合手术治疗复杂性眼病的远期疗效。方法1994年6月至2001年6月,107例(107只眼)眼前后段复杂病变的患者于我院在临时人工角膜下行玻璃体视网膜手术,再联合穿透性角膜移植术,术后局部及全身应用糖皮质激素,并随访观察患者视力、眼压、角膜植片及眼底情况。手术治愈标准:(1)植片透明;(2)视网膜复位;(3)眼压正常或经药物控制眼压正常。结果 达到手术治愈标准者78只跟(72.9％),手术后眼球保存者92,只眼(86.0％),术后发生植片免疫排斥者34只眼(31.8％),眼球萎缩13只眼(12.2％),继发性青光眼15只眼(14.0％)。术前存在增生性玻璃体视网膜病变(PVR)患眼的视网膜手术治愈率与无PVR者比较,差异有显著意义(x2=3.90,P<0.05)。结论 临时人工角膜下眼球前后段联合手术是治疗角膜明显混浊合并玻璃体视网膜病变的有效方法。远期失败的主要原因是角膜植片内皮功能失代偿和增生性玻璃体视网膜病变。(中华眼科杂志,2004,40:514-516)     

Cryopreserved amniotic membrane transplantation for the management of symptomatic bullous keratopathy

Background: To report the results of cryopreserved human amniotic membrane transplantation for the management of symptomatic bullous keratopathy. Methods: Prospective non‐comparative interventional case series study. Consecutive cases with symptomatic bullous keratopathy for more than 12 months not amenable to conservative treatment were managed with amniotic membrane transplantation. They were recruited over a 5‐year period (September 1999 to November 2004) in one referral centre. Only one eye of each patient (the worse affected eye in bilateral cases) was operated. A 360 degree conjunctival peritomy was followed by removal of the diseased corneal epithelium. Amniotic membrane was transplanted over the cornea as a patch and sutured to the free conjunctival edges. Primary outcome measures were ocular pain and epithelial defects; secondary measures were visual acuity and ocular surface inflammation. Results: Four out of 85 recruited cases did not complete the minimum observation of 12 months and were excluded from the study. The mean follow‐up period for the remaining 81 cases was 21 ± 4.2 months (range 14–34 months). Seventy‐one (87.6%) eyes became asymptomatic with healed epithelium, seven required repeated amniotic transplantation and three underwent penetrating keratoplasty. Visual acuity improved in 64 (79%) patients and remained unchanged in 14. No complications were recorded. Conclusions: Amniotic membrane transplantation is an efficient and safe treatment for symptomatic bullous kerato pathy, when penetrating keratoplasty is not available. It has been shown to alleviate pain, promote corneal epithelialization and reduce conjunctival inflammation whereas in some cases it may also improve visual acuity.     

人工角膜支架及其生物相容性的研究进展

除了传统的穿透性角膜移植术和角膜内皮植入术外,人工角膜植入术是一种严重性角膜疾病终末期光学增视性选择性治疗方法.人工角膜最常见的结构是柱镜-裙带型,即由中央透明光学柱镜和周围裙边支架两部分组成.支架材料良好的生物相容性是人工角膜植入成功的关键.随着高分子材料科学的发展,支架材料的种类愈加丰富,对生物相容性的要求也愈加提高.目前常见的人工角膜主要以无机、有机或/和生物材料作为支架,不同材料在实际应用中的相容性和优劣性有所差异,了解这些特性有助于提高人工角膜植入的成功率.     

Superficial hypertrophic dendritic epitheliopathy occurring before and after penetrating keratoplasty in a patient with psoriasis

PURPOSE: To report a patient with superficial hypertrophic dendritic epitheliopathy that occurred in 1 eye after keratoplasty and in the other eye that had not undergone previous corneal transplantation. In both eyes, the epitheliopathy recurred even after subsequent penetrating keratoplasties. METHODS: Case report. RESULTS: A patient with chronic eyelid and ocular surface disease secondary to psoriasis was monitored over a 17-year period. During this time, the patient developed a superficial hypertrophic dendritic epitheliopathy of the left eye 3 years after corneal transplantation. In the right eye, which had not undergone a penetrating keratoplasty, the patient was also noted to have a superficial hypertrophic dendritic epitheliopathy that changed morphologies over the ensuing 5.5 years. Both eyes subsequently required penetrating keratoplasties for decreased vision secondary to subepithelial scarring. After surgery, both corneas suffered recurrences of the superficial hypertrophic epitheliopathy. CONCLUSION: In addition to the original findings that superficial hypertrophic dendritic epitheliopathy occurs in postkeratoplasty eyes, this condition can also occur in corneas that have not been transplanted previously. The morphology of these lesions can vary.     

Glaucoma after corneal replacement

Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy.     

Five year follow up of biocolonisable microporous fluorocarbon haptic (BIOKOP) keratoprosthesis implantation in patients with high risk of corneal graft failure

AIM: To study the anatomical and visual performance following implantation of a model of artificial cornea and to evaluate the postoperative long term complications. METHODS: 11 eyes of 11 patients with bilateral corneal blindness considered as potentially having high risk of failure of penetrating corneal keratoplasty were implanted with biocolonisable Kpro keratoprosthesis (BIOKOP I, FCI, Rantigny, France) in the period between January 1996 and May 1998. Only one eye was implanted in all patients and followed up for a period of 60 months. The visual outcome, anatomical and functional stability, complications, and the general performance of the keratoprosthesis were evaluated. RESULTS: The keratoprosthesis (BIOKOP I) only 36.3% remained in position to date. In the patients' last visit five eyes (45.4%) were blind and one (9.0%) showed a slight improvement in the best corrected visual acuity (BCVA) in comparison to preoperative tests. Six eyes (54.5%) showed improved BCVA before having postoperative complications. Four eyes underwent replacement of a BIOKOP I Kpro with a BIOKOP II as a result of extrusion. The keratoprostheses remained anatomically in situ for a mean of 25.5 months and their functional performance period was limited to a mean of 22 months. CONCLUSION: Corneal keratoprosthesis (BIOKOP I, II) does not provide a stable anatomical relation with the surrounding ocular structures. Its ability to restore vision is limited to a short postoperative period in eyes implanted with severe ocular surface disease.     

Penetrating corneal transplant with inadvertent corneal button inversion

PURPOSE: To report a penetrating corneal transplant in which there was inadvertent inversion of the corneal button. DESIGN: Interventional case report. METHODS: A 48-year-old man with lattice corneal dystrophy had a third penetrating keratoplasty in the right eye 3 years after the second procedure and 2 years following renal transplantation. RESULTS: Histologic examination of the corneal button from the second penetrating keratoplasty disclosed inadvertent corneal graft inversion. Survival epithelium from the donor in the anterior chamber may be explained by the ocular anterior chamber-associated immune deviation or by the patient's systemic cyclosporine A (CsA) treatment after renal transplantation. CONCLUSIONS: Histologically proven corneal button inversion is a rare cause of corneal graft failure.     

Histology of human conjunctival transplantation

The technique of conjunctival transplantation has proven very successful in reestablishing an intact ocular surface in patients with severe ocular surface disease in whom conventional treatment has failed. We present follow-up on the histology of the transplanted conjunctival tissue in four alkali-burned patients who underwent penetrating keratoplasty 3-28 months following conjunctival transplantation. The corneal button was re-epithelialized in all patients. The fate of the transplanted tissue agreed with experimental observations made in the rabbit model, i.e., under areas of vascularization and inflammation, the transplanted tissue resembled conjunctiva with numerous goblet cells and 3-4 cell layers of nonkeratinized, stratified epithelium. In one patient, a definite "transition zone" from conjunctival to corneal appearing epithelium was seen in an area with minimal inflammation and vascularization, again confirming the animal results showing that transdifferentiation of conjunctival to corneal epithelium can occur.     

Long-term follow-up of corneal graft survival following bone marrow transplantation in the Maroteaux-Lamy syndrome.

PURPOSE: To present a case of Maroteaux-Lamy syndrome (MLS, mucopolysaccharidosis [MPS] type VI) who underwent bone marrow transplantation (BMT) for gene transfer at the age of 13, and penetrating keratoplasty at the age of 17, and maintained clear corneal grafts bilaterally for 13 years. To our knowledge, this is the longest follow-up reported on corneal graft survival in a patient with MLS and BMT. METHODS: In 1982, BMT was successfully performed on a 13-year-old girl with MLS with growth retardation, typical facial features, skeletal and joint deformities, hepatosplenomegaly, cardiopulmonary dysfunction, and corneal clouding. Corneal transplantation was done on the left eye in 1986, and on the right eye in 1987 (6 months later) without difficulty or complication. RESULTS: Thirteen years postoperatively, the patient was systemically well, and both eyes retained clear corneal grafts. CONCLUSION: BMT retarded further dysfunction from MLS, and the corneal transplants retained clarity. Further controlled studies with longer follow-up are required to establish the efficacy of BMT in ocular manifestations of MPS or MLS.     

Lamellar transplants in keratoconus.

Lamellar keratoplasty was done in 18 eyes with keratoconus in an attempt to obtain a more satisfactory postoperative refractive error than that after penetrating keratoplasty. The refractive error after lamellar keratoplasty was better than that after 7.5-mm penetrating keratoplasties, but the vision was not as good. Because of the poorer vision, lamellar keratoplasty should probably be reserved for those with large eccentric cones and patients who are not good candidates for penetrating transplants.     

Wound dehiscence after penetrating keratoplasty

PURPOSE: To assess the patient characteristics, risk factors, and outcomes of penetrating keratoplasty wound dehiscence. METHODS: Retrospective chart review of 30 eyes of 29 patients with corneal grafts who underwent repair of penetrating keratoplasty wound dehiscence from January 1, 1998 to December 31, 2003, followed on the Cornea Service at Wills Eye Hospital. RESULTS: The mean time from penetrating keratoplasty to wound dehiscence was 7.5 years (range 1 week to 31 years). The mean age at time of wound dehiscence was 66 years (range 28-98 years). One eye developed wound dehiscence following suture removal, whereas the remaining 29 eyes sustained trauma-induced dehiscences. Falls were the most common mechanism of trauma, especially in the elderly population. There was a wide range of visual outcomes in the 21 patients followed for 1 year, with 4 patients maintaining best corrected visual acuity between 20/20 and 20/40 and 5 patients with light perception vision at 1 year. There were no cases of endophthalmitis. CONCLUSIONS: Patients with corneal transplants have a life-long risk for wound dehiscence. This complication may be reduced by the regular use of eye protection in all corneal transplantation patients.