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PURPOSE To specify a keratoprosthesis (KPro) power value for use with an intraocular lens (IOL). METHODS Raytracing software was used to determine the imaging properties of both the natural cornea and conceptual KPro designs, and IOL power calculation methods were reviewed. Traditional calculations use 'thick lens' models for the overall eye, while also using 'thin lens' approximations for the cornea and IOL. The power of the natural cornea acts approximately at the apex, although this is unlikely to be the case for a KPro. The IOL location is determined using an empirical adjustment that is calculated from clinical results for natural eyes. RESULTS The use of a KPro has a similar optical effect to corneal refractive surgery, where the cornea no longer matches the original eye. A modification of the 'double-K' calculation method can be used by specifying the KPro effective power at the original corneal apex, but still estimating the postoperative IOL location using the original corneal power. The KPro power is measured by assembling the KPro with fluid and a window to simulate the way it is used, recording the best focus power at room temperature with a 3 mm diameter aperture, rescaling to the in situ power at 35°C using refractive index changes, and then rescaling again to the power expected relative to the original corneal apex. When expressed as a K value, a keratometer refractive index of 1.332 is proposed. If necessary, clinical results may be used later to make empirical adjustments to the calculation method. CONCLUSIONS A KPro power can be specified relative to the expected location of the original corneal apex using a keratometer index of 1.332. A double-K calculation can then be used to determine the correct KPro and IOL power values for a pseudophakic eye.

Artificial cornea is an effective treatment of corneal blindness. Yet, intraocular pressure (IOP) measurements for glaucoma monitoring remain an urgent unmet need. Here, we present the integration of a fiber-optic Fabry-Perot pressure sensor with an FDA-approved keratoprosthesis for real-time IOP measurements using a novel strategy based on optical-path self-alignment with micromagnets. Additionally, an alternative noncontact sensor-interrogation approach is demonstrated using a bench-top optical coherence tomography system. We show stable pressure readings with low baseline drift (2.8 mm Hg) for4.5 years in vitro and efficacy in IOP interrogation in vivo using fiber-optic self-alignment, with good initial agreement with the actual IOP. Subsequently, IOP drift in vivo was due to retroprosthetic membrane (RPM) formation on the sensor secondary to surgical inflammation (more severe in the current pro-fibrotic rabbit model). This study paves the way for clinical adaptation of optical pressure sensors with ocular implants, highlighting the importance of controlling RPM in clinical adaptation.

We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.

Purpose: To measure the through-focus curve for eyes implanted with a type 1 Boston keratoprosthesis (KPro) and compare it to that of pseudophakic controls with fixed pupil sizes. The results should assist in evaluating postoperative visual quality after surgery. They should also help to determine the necessary KPro inventories in terms of refractive power steps. Methods: Autorefraction and manifest refraction were performed on all eyes. The monocular through-focus acuity curve was plotted in reference to the bestcorrected visual acuity by spectacle plane defocus ranging from +5.00 to 5.00 dioptres in 0.50 dioptre increments. These measurements were obtained on KPro-implanted eyes, pseudophakic eyes as controls, and on the same control eyes after fixing the pupil diameter to 3 and 2 mm using black painted iris contact lenses. Results: Ten KPro eyes and five control eyes were included. Good agreement was noted between the subjective refractions and autorefraction in KPro eyes. The average through-focus curve for the control eyes was significantly steeper than that of the KPro curve, but became comparable after fixing the control pupil to 2 and 3 mm. Conclusion: The KPro’s wide depth-of-focus makes the visual acuity less dependent on an exact refractive correction at distance and explains the ‘pseudoaccomodation’ experienced by these patients. This is primarily due to the small pupil diameter of the KPro. The current manufacturing steps in 0.50 dioptre increments appears to be sufficient.

Silk proteins represent a unique choice in the selection of biomaterials that can be used for corneal tissue engineering and regenerative medical applications. We implanted helicoidal multilamellar arginine-glycine-aspartic acid-functionalized silk biomaterials into the corneal stroma of rabbits, and evaluated its biocompatibility. The corneal tissue was examined after routine hematoxylin-eosin staining, immunofluorescence for collagen I and III, and fibronectin, and scanning electron microscopy. The silk films maintained their integrity and transparency over the 180-day experimental period without causing immunogenic and neovascular responses or degradation of the rabbit corneal stroma. Collagen I increased, whereas Collagen III and fibronectin initially increased and then gradually decreased. The extracellular matrix deposited on the surface of the silk films, tightly adhered to the biomaterial. We have shown this kind of silk film graft has suitable biocompatibility with the corneal stroma and is an initial step for clinical trials to evaluate this material as a transplant biomaterial for keratoplasty tissue constructs.

Functionalization of material surfaces can improve their biointegration and bactericidal effect. To expand the biomedical applications of titanium in artificial cornea implantation surgery, titanium alloy substrates were coated with polydopamine and dual bound with recombinant vascular endothelial growth factor (VEGF) and anti-microbial peptide (AMP), SESB2V. Successful chemical binding was assessed with attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Coating thickness was assessed by atomic force microscopy. Cellular studies revealed that the functionalized substrates displayed the abilities to enhance primary human corneal fibroblast adhesion, proliferation, and viability. Angiogenesis assay with human mesenchymal stem cells was used to verify the biological functions of immobilized VEGF while bactericidal assay was evaluated for the anti-microbial activities of immobilized SESB2V peptide. We found that the titanium surface that was sequentially functionalized with VEGF and SESB2V had enhanced fibroblast proliferation and anti-microbial properties. The incorporation of such peptides into an artificial cornea implant is important for implant-tissue integration and wound healing. This may improve implant integration and reduce the risk of device infection following artificial cornea implantation.

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.

Corneal disease is the second most common cause of blindness in the word. It is estimated that 45 million people worldwide are bilaterally blind and 10 million are affected by corneal blindness. Corneal blindness mostly affects the population in the equatorial zone, due to the high exposure to UV light. Corneal grafting presents complications such as rejections and the lack of donor material and resources. Conventional cornea grafting (keratoplasty) is not advised for patients with bilateral corneal blindness or for those who suffer from a range of clinical problems including tear deficiency, chemical burns and uncontrollable intraocular pressure. At present, an artificial cornea, i.e. a keratoprosthesis (KRPO), is the only alternative to keratoplasty (corneal donor transplantation). Cornea implants consist of a clear optic part and a surrounding ring known as the skirt, which needs to integrate with the sclera of the eye. Currently used skirt materials lead to poor tissue integration, a major failure of cornea implants. Better integration may be achieved when using a bioactive skirt material, which adapts to the metabolic activity of the cornea. For this purpose, high density polyethylene (HDPE), polyether ether ketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) films provide interesting possible alternatives, if they can be rendered bioactive. This study investigated the potential of using surface modified polymer films to fabricate the skirt. To improve bioactivity of the materials a two-step treatment using chemical surface modification (immersion in NaOH) and formation of apatite layers from Simulated Body Fluid (SBF) was applied. The effectiveness of the different molarity of the NaOH on the formation of the bioactive layer was investigated. Results showed that with an increase in NaOH concentration the wettability improved but also some changes to the topography (increase/decrease of roughness) of the polymers were observed. Moreover, 10M NaOH treatments resulted in more rapid formation of the apatite layer when compared with a non-treated and lower molarity solution. As immersion time in SBF increased, further nucleation and growth produced a thicker apatite layer which can be expected to be highly bioactive. Interestingly, the apatite growth is dependent on both the concentration of NaOH solution and the structure of the polymer surface. It was concluded that hydroxyapatite layers were formed on HDPE, PEEK and UHMWPE films after they were incubated in 1.5 SBF, which promises to render such thin-film structures bioactive – a necessity if they are to be integrated into artificial cornea. The Ca/P molar ratio of the apatite deposited on the polymers increases with NaOH strength and SBF incubation time. The favourable effect of NaOH on apatite formation may at least partly be attributed to an increased wettability of the polymer films after such treatment, as well as to the modified topography. The apatite layer contained phosphate and carbonates ions, providing potentially good in vitro bioactivity on polymeric films. The inorganic layers are chemically stable as the calcium deposited on the films did not dissolve fully when immersed in water for one week. This demonstrates that polymer films can be rendered bioactive, using the described approach, hence providing potential materials suitable for artificial cornea implants.

The search for a substitute for the natural cornea dates back more than 200 years. Although several devices have been developed and trialled, very few have had successful long-term results and continue in regular clinical use. Keratoprosthesis (KPro) surgery is complex and should be performed in centres with an experienced multidisciplinary team. Currently available KPro devices range from the totally synthetic, such as the Boston KPro, to the totally biological tissue-engineered artificial cornea. The osteo-odonto keratoprothesis combines a synthetic optic with a biological haptic. All keratoprostheses have significant limitations, although visual improvement is possible with each of the devices in clinical use today. This review discusses these devices with emphasis on their indications, surgical techniques and results, before briefly exploring emerging devices and innovative approaches for the future.

A perforating keratoprosthesis was implanted on five patients with densely vascularized leukoma of the cornea. Two of the patients experienced no or minimal visual improvement due to posterior segment pathology. Considerable visual improvement was achieved for the other three patients. Extrusion of the prosthesis frequently occured but it could be replaced without loss of the visual gain.

During the years 1974–1987 a total of 27 two-piece keratoprostheses were implanted in 25 eyes of 22 different patients with bilateral blinding anterior segment disease with no possibility for a successful corneal transplantation. The prosthesis design and the surgical procedures used are described. The healing in and fixation of the prostheses were initially good in all cases, but 9 prostheses were lost or removed because of complications during the postoperative period of observation. The prosthesis retention time was significantly longer than that earlier achieved by the use of a one-piece prosthesis. In 18 of 27 cases a visual acuity of 6/60 or better was obtained. Postoperative complications included necrosis of the tissues covering and supporting the prosthesis, infection around the prosthesis, overgrowth of the surrounding tissues and the development of dense retroprosthetic membranes. Despite the obvious risks, keratoprosthesis surgery in a small number of patients with severe corneal disease represents the only potential hope for a visual rehabilitation, and should therefore be considered.

A total of 12 one-piece keratoprostheses were implanted in 6 eyes of 6 different patients with bilateral blinding, severe corneal disease with no possibility for a successful corneal transplantation. The prosthesis and the surgical procedure used are described. The short-term results were good, with 4 of the 6 patients obtaining a substantial visual improvement. In the remaining 2 patients preexisting pathology in the posterior segment of the eye was strongly suspected. However, the long-term complication rate was high, the chief problems being tissue necrosis around the prosthesis with eventual prosthesis loss and the development of retroprosthetic membranes. Repeated replacements of keratoprostheses extruded or removed because of complications were possible with restoration of the vision obtained after the first implantation.

This paper is aimed at establishing a particular chronological priority issue in the convoluted history of artificial cornea. According to existing records, the first keratoprosthesis made from polyurethane was developed by Caldwell and Jacob-Labarre in the late 1980s. This paper demonstrates that in fact the first polyurethane keratoprosthesis was proposed and designed in 1985 by Lawrence Hirst, an Australian ophthalmologist then working in St Louis, USA. The first prototype was manufactured in January 1986 by Thermedics Inc according to Dr Hirst's instructions from Tecoflex, a transparent polyurethane developed by the same company. This keratoprosthesis, which also had a porous skirt, was inserted intralamellarly in a monkey cornea and followed up clinically for about 3 months. There were no significant postoperative complications, and the histology of the explant indicated proper biointegration of the prosthetic skirt within the host stromal tissue. Because of a delay in the manufacture of further prototypes and to Dr Hirst's decision to return to Australia, the project was eventually abandoned. As no report was published on this development, the present paper is entirely based on original documents held in Dr Hirst's archives.

The cornea is a transparent tissue of the eye, which is responsible for the refraction of incoming light. Both biological corneal equivalents and synthetic keratoprostheses have been developed to replace donor tissue as a means to restore vision. However, both designs have drawbacks in terms of stability and biocompatibility. Clinically available synthetic devices do not support an intact epithelium, which poses a risk of microbial infection or protrusion of the prosthesis. In the present study, type I collagen was immobilized onto poly(vinyl alcohol) (PVA-COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. Human and rabbit corneal epithelial cells were air-lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA-COL. The epithelial sheet expressed keratin 3/12 differentiation markers, the tight junction protein occludin, and had characteristic microvilli structures on transmission electron microscopy. Functionally, the stratified epithelium contained normal glycogen levels, and an apical tight-junction network was observed to exclude the diffusion of horseradish peroxidase. Furthermore, the epithelium-PVA-COL composite was suturable in the rabbit cornea, suggesting the possibility of using PVA-COL as a biocompatible material for keratoprosthesis.

Substituting the natural cornea is no easy task. Researchers have shaped and honed methods for over 200 years, seeking the ultimate surrogate. Today the Boston type 1 keratoprosthesis is the world’s most commonly used artificial cornea. Advances in both surgical technique and postoperative management have drastically reduced the prevalence of endophthalmitis. The authors conducted a systematic review of endophthalmitis arising from the Boston type 1 technique. Medline, Embase, Google Scholar and The Cochrane Library were systematically searched alongside grey literature sources for relevant studies. Many methods are currently employed to reduce complications including vancomycin prophylaxis and the use of bandage contact lenses. The results will be presented with a view to collate the research conducted to date.

This presentation will address the current status of keratoprosthesis globalization, world-wide, with special attention to use in less economically developed countries. The author will review the existing literature, and discuss obstacles and opportunities encountered in implementation of keratoprosthesis surgery in blind, indigent patients, world-wide. Implantation of keratoprostheses, including the modified osteo-odonto keratoprosthesis and the Boston keratoprosthesis, is increasing internationally, and in particular, in less economically developed nations with large proportions of indigent, corneal blind patients. Based on the published literature, specific complications, such as device extrusion and infectious endophthalmitis, may be more common in these settings. Increased implantation of keratoprosthesis use in less economically developed countries will bring new challenges. We can expect increased reports of severe complications after keratoprosthesis implantation, particularly in the poorest patients. New designs and approaches are needed before keratoprosthesis implantation can be fully globalized.

Purpose Comment the Barcelona experience with different types of keratoprostheses Methods Six cases of different keratoprostheses implanted at the Barraquer Eye Center in Barcelona from 1955 to 2014 are discussed. Results The first keratoprosthesis implanted in Spain was a Dorzee acrylic keratoprosthesis in a case of bilateral chemical burn in 1955 with good functional and anatomic result for five years, when extrusion ocurred with simultaneous superior retinal detachment. The second case refers implantation of a Dorzee-Barraquer-Cardona acrylic keratoprosthesis in 1958 in a patient with terminal glaucoma. There was good anatomical retention until the patient’s death in 1970. In the third case a Cardona keratoprosthesis was implanted in 1960 after severe failure of two corneal transplants. Acute endophthalmitis ocurred after a satisfactory anatomical and functional result for 8 years. The fourth case shows extrusion of a Teflon-supported keratoprosthesis (Girard). The fifth case discusses implantation of an osteo-odonto-keratoprosthesis (Strampelli)after blast injury with good anatomical and functional result for 10 years. The last case refers to the experience with the Boston keratoprosthesis in our Center since 2006. Conclusion Clinical experience for more than 50 years at the Barraquer Eye Center confirms evolution of the original Dorzee-Keratoprosthesis to the nowadays widely used Boston keratoprosthesis. In spite of progress in surgical technique, design and postoperative treatment, anatomical and functional results continue being a challenge for KPro surgeons due to the relatively high frequency of unresolvable serious sight-destructive complications.

Highly biocompatible polymer membrane was developed for an artificial cornea in this surface modification study. Heterobifunctional silicone rubber membranes (hetero-SR) were prepared by grafting different functional polymers on each side of a silicone rubber membrane (SR). A novel type of bifunctional membrane was developed with the upper-side favoring cell attachment and growth, and the lower-side suppressing cell adhesion. The preparation of heterobifunctional membranes, characterization of polymer membrane surface properties such as ATR-FTIR and ESCA and contact angle, and biological analysis (in vitro and in vivo studies) were investigated in this work. Based on the biological analysis, the heterobifunctional membrane displays promising potential for use as an artificial cornea.

Our goal was to: 1) modify poly(vinyl alcohol) hydrogels intended for use in a synthetic cornea to absorb ultraviolet light and 2) develop molding procedures for the fabrication of the device. Two ultraviolet light-absorbing monomers were incorporated by copolymerization. The resulting hydrogels protected against ultraviolet light, were not toxic to corneal fibroblasts, and the protection did not diminish during prolonged aqueous exposure. A novel keratoprosthesis molding procedure was developed that made use of the phase transition properties of mixtures of poly(vinyl-trifluoroacetate) and acetonitrile. In this procedure the keratoprosthesis was shaped and a fibrous skirt was bonded to it in a single operation. Composite keratoprostheses were designed and prepared for in vivo testing.

Boston Keratoprosthesis is the most commonly used Keratoprosthesis worldwide. It is a collar button kind of Keratoprosthesis carried on a corneal graft. The prerequisites for a type 1 Boston Keratoprosthesis include the following 1) Bilateral corneal blindness 2) Reasonably healthy posterior segment 3) Well controlled Intraocular pressure or combine a shunt surgery with the Keratoprosthesis 4) Moist eye 5) Good blink 6) Well formed fornices 7) Committed to regular follow ups and Understands the potential risk involved in the surgery The current indications for Boston type 1 Keratoprosthesis are 1) Multiple failed grafts 2) Limbal stem cell deficiency 3) Ocular burns( chemical/thermal) 4) Aniridia 5) Pediatric corneal opacities 6) Silicone oil induced keratopathy Contraindications 1) Poor /Incomplete blink 2) Severely damaged lid apparatus post chemical injuries 3) Keratinized ocular surface (would be an indication for Boston type 2/MOOKP) Design modifications like addition of more holes in the back plate, the use of the titanium locking ring, Use of a bandage contact lens and prophylaxis with antibiotics with the present design have improved the outcome and retention rates of the Keratoprosthesis. Further research in the form of a titanium back plate to reduce the rates of retroprosthetic membrane formation is being tried.

Having one biomaterial for a wide range of clinical applications may mean that the physico-chemical properties of the material surface needs to be tailored to fulfill the allrequirements of the actual application. One example of tailoring surface properties of one and the same base material may include the definition of areas where cells attach to and deposit extracellular matrix. As for ophthalmological applications, this notion can be traced to de Quensgy's review, published in 1789. There, the author outlined basic features of the keratoprosthesis: a central optical cylinder and a haptic for firm positioning in the surrounding tissue. Incomplete biocompatibility of materials used, aside from issues of ethics and patient's acceptance, render problems. Using chemical, physical and nanotechnological methods, features of the material can be dramatically increased. There are different strategies to induce biomimetic cell-tissue-material interaction by modifying the surface on one base material - as well as the use of metallic biomaterials and drug-containing particles. These findings aid the development of next-generation biomaterials where surface-effects are utilized in different therapeutic clinical applications.

Osteo-odonto-keratoprosthesis (OOKP) is the procedure of choice for end stage ocular surface disease with severe dryness and keratinisation, and in those eyes with structural and functional lid abnormalities. The device retention rates and visual outcomes of the OOKP are far superior than any other keratoprosthesis. However, this device can have complications at every step during surgery and unto many years afterwards. Complications after the Stage 1 include: mucosal thinning and ulceration, mouth related, resorption of the implanted lamina and infections. Complications after the Stage 2 include: mucosal thinning and ulceration, mucosal overgrowth onto the optic, lid malpositions, lamina problems like resorption, tilting, infection, posterior segment complications like retinal detachment and vitreous haemorrhage. Glaucoma is a major cause of visual loss in a successful OOKP eye. Social and psychological complications can arise after visual restoration or the preexisting problems can continue. In addition, operative complications, systemic morbidity and anesthetic related problems do occur. A majority of the complications can be sight threatening if not rectified appropriately in a good time. They may be preventable or reducible with correct patient selection, improvements in preoperative and postoperative patient care and education. A sound surgical technique, reflective learning, harnessing the medical technology and multidisciplinary team approach can effectively reduce and treat the complications of OOKP surgery. Multidisciplinary team approach, having an experienced anesthetist and psychologist on board, and a continuous social support will prevent patient morbidity and optimise good outcomes.

Purpose Development of synthetic eye prosthesis to provide a long term stable keratoprostesis Methods Synthetic hydrophobic and hydrophilic biomaterials were selectively modified by physical and chemical nanotechnological methods. The modified biomaterials were tested in cell culture experiments (fibroblasts L929 and primary epithelial cells, porcine) and implanted into rabbits eyes. The hydrophobic material was implanted finally into eyes of ultima ratio patients. Results After very successful in vitro evaluation, keratoprostheses were implanted to rabbit eyes (New Zealand white rabbit) and showed excellent in vivo performance in the animal experiment.As for the hydrophibic material, no adverse reaction was observed after follow up of 2.5 years in human eyes. Conclusion We could develop a new keratoprosthesis which is well tolerated in human eye.

Purpose To list the options for an edentulous patient requiring OOKP surgery for rehabilitating corneal blindness. Methods Literature review, personal experience, and theoretical considerations. Results Options include an OOKP allograft from a living (related or unrelated) donor which necessitate systemic immunosuppression, a tibial bone allograft (depends on good bone density), and a Pintucci (Dacron) keratoprosthesis. None of these has the longevity of an OOKP proper. Other options, as yet not properly studied, include cadaveric OOKP allografting, and synthetic OOKP analogues. The latter has the advantage of the possibility of mass manufacture, no risk of transmission of blood-borne infections, and no size constraints limiting optical cylinder design. Conclusion Options do exist for the edentulous patient requring OOKP surgery for rehabilitation of corneal blindness. In the long term, the synthetic OOKP analogue holds the best promise.

Two winners have emerged among dozens of keratoprostheses (KPros) which have come and gone. The Osteo-odonto-keratoprosthesis is the device of choice for end stage inflammatory ocular surface disease associated with a dry eye, such as Stevens Johnson syndrome and ocular cicatricial pemphigoid. The Boston Type 1 keratoprosthesis is successful for wet blinking eyes and can be considered as an alternative to high risk keratoplasty in highly vascularised corneae or in multiple previous graft failure. The main advantage of these "hard" KPros is optical clarity. Whilst the field of view may be somewhat limited, there is no astigmatism and the optical surface is usually bare and clear. Hard KPros depend mostly on bio-inertness as opposed to biointegration. Soft KPros have the theoretical advantages of the possibility of having the same mechanical moduli as the host tissue thus reducing stress at the interface when the eye is subjected to minor trauma, intraocular pressure measurement by applanation, and drug penetration. However, much effort has to be directed towards adequate integration (healing), and either total and smooth epithelialisation or no epithelialisation whatsoever. Partial epithelialisation, tear meniscus, and buckling of a soft optic contribute to poor optical performance and thus poor vision.

Purpose To present the difficulties of managing vitreoretinal complications in patients with OOKP and open a discussion about future strategies to prevent and deal with these problems. Methods Retrospective review of cases. Results Vitreo-retinal complications occurred in 14 of 54 patients receiving OOKP surgery. These included vitreous hemorrhage (4 patients), rhegmatogenous retinal detachment (3 patients), endophthalmitis with retinal detachment (5 patients), endophthalmitis without retinal detachment (1 patient) and intraoperative choroidal hemorrhage (1 patient). Most cases of endophthalmitis presented late and may result from lamina resorption, leak and hypotony. The prognosis of retinal detachment in an eye with OOKP was poor with successful repair in 1 of 3 cases not related to endophthalmitis and 0 of 5 cases with endophthalmitis. Overall, pars plana vitrectomy was performed on 10 occasions (8 patients), of which 2 were endoscopic and 2 utilised a temporary keratoprosthesis. Conclusion There is a relatively high rate of posterior segment problems in OOKP patients and their management is challenging both in assessment (limited view and ultrasound amenability) and surgical approach. Surgical outcomes were poor for these complications. Other concepts in management, including endoscopic vitrectomy at stage I surgery should be considered, which will be discussed.

Purpose To report indications and outcomes from a multicenter study on the Boston Type 1 keratoprosthesis (Kpro). Methods Kpro data was collected and analyzed at a central collection site. Kpro survival and visual acuity are the main outcomes measured. Results 324 Boston Type 1 Kpro implants (310 patients) from 19 surgeons were included. The average age was 63.2±18.7 years, 47.6% female, 53.0% right eyes. The average number of penetrating keratoplasties (PKP) prior to kPro insertion was 1.9±1.5 (range 1-8). Pre-operative diagnosis was divided into 3 different categories: “chemical” (32 eyes), “autoimmune” (39 eyes with either Stevens Johnson Syndrome [SJS] or Ocular Cicatricial Pemphigoid [OCP]), “other” (n=188), and “unknown etiology” (n=65). The mean preoperative logMAR visual acuity was 1.77±0.62 (48.1%; n=156 eyes); 32.4% hand motion and 14.2% of light perception. Average follow-up time was 16.3±14.6 months (range 0.7 – 59.4). The overall retention rate was 92.0% (n=298). Median survival time (months) was 60.9 (autoimmune), 99.1 (chemical), & 139.3 (other). The median survival time for patients with autoimmune disease was significantly lower than for other diagnoses (p

Purpose In vitro studies of human cornea stroma keratocyte proliferation and cytokine secretion on the various kerato-prosthesis skirt material. In the development of an artificial cornea, an appropriate skirt material which encourages keratocytes proliferation is important to help wound healing and integration. Epidermal growth factor (EGF), insulin growth factor (IGF-1) and hepatocyte growth factor (HGF) stimulate corneal keratocytes proliferation. IGF-1 and EGF have an anti-apoptotic effect of keratocytes. Conclusion: Methods Three materials were studied: Hydroxyappatite (HA), titanium substate (TiO2) and aluminium oxide substrate (Al2O3). Corneal stromal were seeded on top of these materials for EDU image assay and real time PCR analysing. Conditioned cell culture medium was collected for cytokine array. Results Cytokine array showed the levels of EGF, IGF-1 and HGF were no statistical significance among the HA, TiO2 and Al2O3. RT-PCR, showed that the expression level of EGF, IGF-1 and HGF were highest with TiO2 substrates and lowest with HA substrates with statistical significance. Edu assay showed a comparable number of proliferating cells on the HA and TiO2 with significantly more cells on the Al2O3 dics. Conclusion TiO2 is a comparable material to HA at promoting corneal keratocytes proliferation, hence is a possible alternative material to generate synthetic keratoprosthetic skirts.

Purpose To illustrate the implantation technique & tolerance of a novel wireless silicone-encased intraocular pressure transducer in rabbit eyes. The device can conceivably provide a reliable way to measure the IOP in situations where measurement is difficult with the present technology, for instance in eyes with keratoprosthesis implants. Methods The transducer, manufactured by Mesotec GmbH (Hannover, Germany), is a fully digital ultra miniature system, integrating pressure sensing, data handling and telemetry on a single microchip. The microchip is connected to a telemetry coil and requires no internal power source. The data is received using an external reader unit. The transducers were initially tested for calibration in enucleated bovine eyes. They were sterilized with ethylene oxide. They were implanted either through a corneal autograft (n=2) or through a large limbal incision (n=2) and placed either in the sulcus (n=2) or suspended into the vitreous cavity (n=2) after removing the crystalline lens. In one rabbit (SHAM), the crystalline lens was removed but no implant was placed. The eyes were closed with interrupted 10-0 nylon sutures. Daily observations and weekly full clinical examinations were performed. The readings obtained by the transducer-readers were compared with those obtained by Tonopen. Results The transducers were well tolerated, with minimal transient post-operative intraocular inflammation that was similar in both the experimental and SHAM groups at comparable time-points. The pressure obtained by the transducers showed good correlation with those obtained by Tonopen. Conclusion Our animal studies show that the transducer can be easily implanted and is well tolerated inside the rabbit eye, up to 4 months at the present time.

Purpose To present a retrospective review of keratoprosthetic implantation and retention in patients with congenital corneal opacities. Methods Pediatric patients younger than seven years old, the average age of permanent visual loss from understimulation of the visual cortex, were selected from a single center Boston Type I keratoprosthesis database and categorized by 1) primary diagnosis, 2) short-term visual outcome, and 3) post-operative complications. Results Seventeen patients, with an age range of 41 days up to 6 years, were selected from a database of over one hundred and forty patients. Six had a primary diagnosis of sclerocornea and eleven had Peter’s anomaly. Visual outcome after one year improved in fourteen of the patients, with patients who previously could not detect light to subsequently being able to fixate and follow or even read allen cards. The remaining three patients showed no improvement in visual acuity but also no worsening from their baseline condition. In terms of post-operative complications of the optic, two had retroprosthetic membrane formation, and another patient required replacement of the keratoprosthesis due to phthisis and optic melting. From a retinal standpoint, four patients had retinal detachments. There were no cases of choroidal hemorrhaging or hypotony in these patients. Conclusion Based on visual outcome, the Boston Type I keratoprosthesis is a safe and effective procedure for patients with congenital corneal opacities. With great retention, the artificial cornea is a viable option for prevention of amblyopia. Due to comorbidities such as congenital cataracts, congenital glaucoma, and retinal detachments, it is crucial to have glaucoma and vitreo-retinal surgeons on hand when managing and implanting keratoprosthesis in a pediatric population.

Purpose Aim is to evaluate the incidence, surgical treatment and outcomes of retinal detachment in eyes that had undergone Falcinelli's modified osteoodontokeratoprosthesis (MOOKP). Methods Technological and surgical advancements allow to treat successfully a severe pathology as retinal detachment, even in eyes with keratoprosthesis (KPro). The autors accurately describe the surgical technique which usually uses an Eckardt or Landers temporary KPro, a pars plana vitrectomy and a gas or silicone oil tamponade, even if in selected cases it is possible to perform just a scleral buckling. Results By the means of the described techniques good anatomical success and improvement in visual acuity have been obtained. Nine retinal detachments were successfully operated, one retinal detachment was unsuccessfully operated, four retinal detachments were judged to be inoperable for severe proliferative vitreoretinopathy because of late turning-up to clinical examination and lack of technology in the 70's. Conclusion The autors point out that an accurate MOOKP procedure it is necessary for preventing the retinal detachment. An early diagnosis by echography performed at every clinical examination during the follow-up in patients with MOOKP and an appropriate surgical planning for each case are fundamental for a better anatomo-functional outcome.

The operation is performed in three stages. The first stage consists in preparing the eye to receive and maintain the keratoprosthesis. For this purpose the anterior surface of the eye is cleaned and regularized, eliminating fibrous tissue and the entire epithelium. Subsequently we obtain a 2 x 3 cm graft of buccal mucosa from the inferior lip comprising the entire mucosal and submucosal thickness. The graft is sutured to cover the anterior pole of the eye to promote revitalization. The second stage consists in preparing the keratoprosthesis. A 10 mm disk of tibial bone from the superior part of the medial face of the tibia is obtained using a crown drill. The posterior part of the piece of bone obtained is then cut with a chisel to obtain a thickness of 3 mm. Subsequently the obtained disk of bone is cleaned and a central opening of 3.5 mm is performed to introduce in this opening a PMMA optic cylinder, 9 mm in length, 3.5 mm in diameter in its narrow portion, 4 mm in the wider portion. Fixation is achieved with cyanoacrylate. This is left to dry and then it is introduced into a palpebral pocket of the inferior lid of the patient. The pocket is closed with sutures and the piece is left in place for three months. For the third stage we remove the keratoprosthesis device from the palpebral pocket and if it is found to be in perfect conditions we dissect the buccal mucous membrane which is covering the cornea and perform a central window with a 4.5 mm trephine to remove the transparent or cataractous lens and perform a total iridectomy. The posterior portion of the optic cylinder is introduced into the anterior chamber. The prosthesis is sutured to the anterior pole of the eye with non-absorbible sutures. Finally the buccal mucosa is replaced, covering the entire area. One point of blepharorraphy is applied. Long term results. We started to use this technique in 1988 and after 21 years of experience we have 80% of anatomically perfect results. In 20 % of the cases the prosthesis extruded due to total or partial resorption of the bone. It has to be emphasized that these were cases without any other possibility of treatment. We did 143 cases during these years. The longest follow-up of a prosthesis “in situ” is 19 years. The earliest extrusion was after one year. The complications are the same as for OOKP (glaucoma, retinal detachment, vitritis, extrusion) The functional results depend on the conditions of the retina and the optic nerve. There were many cases with 20/20 vision. The mean value of retention of the prosthesis is 15 years.

Purpose Patients with Type 1 Boston KPRO require the use of a contact lens to avoid complications of drying of the corneal tissue surrounding the KPro. Additionally, these patients require chronic use of topical antibiotics to reduce the ever-present risk of endophthalmitis. This may promote the growth resistant organisms. The purpose of this study is to perform surveillance cultures of contact lenses of KPro patients to determine if organism growth may be detected prior to clinical presentation of infection. Methods Cultures of contact lenses from Boston KPro type 1 patients were performed. All patients were maintained on a prophylactic antibiotic regimen including vancomycin. All contact lenses were removed 1 week to 1 month after insertion. Removal prior to 1 month was necessary when excessive protein deposits were noted on the lens. Lenses were removed cultured and analyzed under electron microscopy. Results 45 patients with a KPro implanted in the last 18 months, the lenses of 15 patients were analyzed in the above manner. These 15 patients had various conditions including Stevens Johnson Syndrome, chemical burns, keratoconus, and multiple graft failures. Of the 15 lenses analyzed, one patient had cultures positive for streptococcus pneumonia, consistent with the patient's presentation of endophthalmitis. Three had cultures positive for coagulase negative staphylococcus although they did not present with any signs or symptoms of infection. Conclusion Surveillance cultures appear to be an effective way to monitor the contact lenses of Boston KPro patients for possible organism growth. The detection of these organisms prior to the clinical presentation of infection could serve as a signal to change the patient's antibiotic regimen.

Modified osteo-odonto keratoprosthesis (MOOKP) is complicated two step surgery. Firstly, we must understand why it is effective for visual recovery of end-stage ocular surface diseases like Stevens- Johnson syndrome. MOOKP have a lot of advantages compared to other K-pros, for example the using auto tissue of canine tooth root and buccal mucous membrane, the tight adhesions between optical cylinder and canine tooth root, the adhesion between MOOKP lamina and sclera or cornea, the strong ocular surface by auto buccal mucous membrane, no inflammation on the back of optical cylinder and so on. However, the precise surgical techniques and proper instructions are necessary to succeed the very first case in newly set surgical center. In Japan, we successfully set up the MOOKP center and did perform 4 cases of MOOKP since 2003. We share our experience about it and point out our modification adjustable for Japanese patients.

Purpose To assess anterior chamber depth in aphakic and pseudophakic patients with Type 1 Boston Keratoprosthesis using anterior segment optical coherence tomography. Methods Sixteen patients who underwent Boston Type 1 Keratoprosthesis implantation were evaluated for anterior chamber depth by the non-contact technique of AS-OCT. Longitudinal cuts were used in evaluation of AC depth. Functional AC depth was defined as the distance between the back plate of the KPro and the anterior surface of the iris. Anatomic AC depth was defined as the distance from the posterior surface of donor cornea to the iris. Both functional and anatomic AC depths were measured nasally and temporally. The distance between the back plate of the KPro and anterior surface of the posterior chamber intraocular lens (PCIOL) was also measured in pseudophakic patients. Results A total of 16 patients were included in this study. There were 9 pseudophakic and 7 aphakic patients. Anatomic AC depths ranged between 0.86mm to 3.2mm. Functional AC depths ranged from 0mm to 2.2mm. Pseudophakic patients had anatomic AC depths between 0.92mm and 3.1mm and functional AC depths between 0mm and 2.2mm. Aphakic patients had anatomic AC depths between 0.86mm and 3.2mm, and functional AC depths between 0mm and 2.2mm. The distance between the back plate of the KPro and PCIOL in pseudophakic patients ranged from 0.14mm to 2mm. Conclusion Anterior chamber depth measurement, combined with AC angle data provide valuable information in the setting of KPro implantation. This may be helpful in monitoring patients post-operatively for anterior segment complications such as crowding of the AC, or occlusion of the angle.

Purpose Glaucoma is one of the most serious problems in Keratoprostheses. Already glaucoma is very frequent in patients with severe changes of the ocular surface requiring keratoprosthesis surgery. About 50% of those patients have pre-existing secondary glaucoma. Preoperatively all efforts should be done to detect its presence very early on. In KPro detection of glaucoma with traditional aids is difficult. A rough estimation of the tension by digital palpation will be the only available method. All indirect clues such as the medical history of glaucoma, echographic signs of disc cupping and anterior synechiae and examination of the visual field should be considered. Methods The incidence of postoperative secondary glaucoma vary among the different kinds of prostheses according to the surgery affecting the anterior segment and the long term anatomic results. In Osteo-Odonto-Keratoprostheses (OOKP) the most vision threatening complication is a primary or secondary glaucoma, due to the extended interventions required in the anterior segment. In Boston Keratoprostheses the risk seems to be somehow less. Results As the absorption of topical anti-glaucomatous medication will not reach the inner eye because of the anatomic barrier in KPro the only promising possibilities of treatment are systemic carbonic anhydrase inhibitors, different kinds of aqueous shunts and endo-cyclo-laserphotocoagulation. Conclusion Glaucoma is still a mayor problem in KPro. PS: This lession will be presented at the KPro-Meeting!!

Purpose Patients with corneal blindness due to mucous membrane pemphigoid and Stevens Johnson syndrome who undergo corneal transplantation carry a poor prognosis for visual recovery. The Boston keratoprosthesis has been demonstrated to provide excellent retention rates and postoperative visual acuity in patients with corneal graft failure, however, poor visual outcomes still occur in patients with underlying autoimmune disease. Methods We reviewed the current literature to determine the results of keratoprosthesis in patients with blinding autoimmune diseases. Results Much of the published literature on keratoprosthesis fails to clearly differentiate outcomes on the basis of the underlying disorder. Based on available evidence, inflammation, retinal detachment, and glaucoma appear to be the most significant complications after keratoprosthesis in autoimmune patients, and a diagnosis of mucous membrane pemphigoid or Stevens Johnson Syndrome appears to be associated with a significantly higher complication rate than other preoperative conditions. Conclusion Patients with autoimmune diseases carry the worst prognosis for success with keratoprosthesis. Improvement in clinical outcomes might be achieved with changes in keratoprosthesis design and material, perioperative therapy, and/or surgical technique. Possible approaches to complications after Boston keratoprosthesis in patients with underlying autoimmune diseases will be discussed.

Purpose To present the development and current status of keratoprosthesis surgery in Eastern Europe. Methods Collection of data from coauthors and other surgeons involved in k-pro surgery. Results Large numbers of surgeries were performed in Filatov's Institute in Odessa (Ukraine), where over 1000 different types of devices developed by Puchkovskaya, Yakimienko and Golubenko were imlanted since 1966. The last model, s.c. "universal separable device" was implanted in over 750 with the best results (extrusion occured in about 2.5% cases). K-pro devices in Russia were mostly developed by S. Fyodorov Z. Moroz, V. Zuyev, ?. Krasnov, V. Volkov, R. Gundorova, N. Ushakov and V. Bedilo. Over 1500 surgeries sine 1969 resulted in the visual aquity improvement in 94% of cases. Haptics were made of titanium, stainless steel and also biocompatible materials (xenopericardium). In Poland about 100 surgeries were performed using mostly Russian and Ukrainian devices. The results were less favorable than in countries of origin. Small numbers were also implanted in other East European states. Conclusion In former Soviet Union keratoprosthesis surgery was well developed in selected centers (Moscow, Odessa). Surgeons in these places have gained extraordinary experience performing hundredes of surgeries. The results presented by the authors were excellent, however they were less favorable in the hands of surgeons from other countries.

Purpose To report the long term results of a supradescemetic corneal implant to restore vision Methods A Keralia "soft" keratoprosthesis was implanted in one eye of a seventy years old woman bilaterally blind and affected by a bilateral limbal stem cells deficiency. Results After four years the implant is still insite, well tolerated. Thi initial visual recovery has been compromized , during the last year, by a progressive opacification of the superficial layer of the device. Conclusion The Keralia supradescemtic implant seems well tolerated in the long term by the human eye. Problems related to the stability of the material should be solved in future.

Purpose to describe the Barcelona experience with the different types of keratoprosthesis for end-stage cicatricial corneal disease. Methods We present 6 cases showing various types of keratoprosthesis which we have used at the Barraquer Eye Center from the 1950´s up to the present. Results We describe the first keratoprosthesis ever implanted in Spain, on a case of severe chemical burn on a young lady. We implanted a Dorzee acrylic keratoprosthesis in 1955. 5 years later she had extrusion of the prosthesis and superior retinal detachment. The second case describes the Dorzee-Barraquer-Cardona acrylic implant implanted in 1958 on a patient with end-stage glaucoma. Patient had good anatomical retention until his death in 1970. The third case describes the use of the Cardona keratoprosthesis in 1960. Patient had good anatomical and functional results for 8 years until suffering from an acute endophthalmitis. The fourth case demonstrates the expulsion of a Teflon-supported keratoprosthesis designed by Girard. The fifth case describes the first implantation of an osteo-odontokeratoprosthesis designed by Strampelli on a blast injury showing good results for 10 years. The last case shows our experience on the Boston keratoprosthesis which we started using in 2006. Finally, we present our technique of the osteo-odontokeratoprosthesis and a summary of our clinical results from 1970´s to the present. Conclusion Our clinical experience for more than 50 years on the use of keratoprosthesis shows that while the surgical technique, design and post-operative treatment of both biological and non-biological keratoprosthesis have improved thru the years, the anatomical and functional success remains a challenge for the KPro surgeon.

Purpose To describe the indications, intraoperative complications, post-operative complications and anatomical and functional results of Type I Boston keratoprosthesis at our eye center in Barcelona. Methods Retrospective interventional case series on 24 eyes of 22 patients who underwent Boston keratoprosthesis implant from May 2006 to May 2008. Results The main indication for Boston keratoprosthesis implantation was a repeated failed graft (mean = 2.33 previous grafts). The most common principal pathologies were: bullous keratopathy, herpetic keratitis, aniridic keratopathy, corneal ectasia, calcific band keratopathy. No major intraoperative complications were noted and average time of surgery was 47 minutes. The mean follow-up time was 7.42 months. The major post-operative complications encountered were retroprosthetic membrane in 2 eyes, endophthalmitis in 2 eyes and corneal graft melting in 1 eye. The mean best corrected visual acuity improved from 0.015 pre-operatively to 0.1 post-operatively. Only one case of extrusion due to melting was encountered which was resolved by a reimplantation of the keratoprosthesis. Conclusion Our short-term experience with the type I Boston Keratoprosthesis is a good alternative for patients with repeated graft failures. Improvement in visual acuity is immediate and only minor complications were encountered.

Purpose: To review the strategies, problems and technical issues in dealing with vitreo-retinal pathology in eyes before, during and after osteo-odonto keratoprosthesis (OOKP) surgery. Methods: A retrospective review of eight consecutive cases in which vitreo-retinal intervention was required in the OOKP programme in the Singapore National Eye Centre. Results: Six eyes had retinal detachments. Three of these had limited previously untreated retinal detachments with traction, detected on b-scan ultrasonography. Repair of the retinal detachments preceded completion of the OOKP procedures although one eye required a repeat vitrectomy for a recurrent detachment with the prosthesis in place. One eye had a massive choroidal haemorrhage resulting in abortion of OOKP stage two surgery. The choroidal haemorrhage resolved, leaving a localized traction-associated retinal detachment that was repaired during repeat stage two surgery. Two eyes had prior retinal surgery for presumed detachments with silicone oil in place prior to OOKP surgery. Stage two surgery was completed with assessment and confirmation of stability of retinal pathology. Two eyes required vitreo-retinal intervention for endophthalmitis. One developed infection after stage two surgery and was successfully salvaged. The other developed endophthalmitis after endoscopic cyclophotocoagulation for glaucoma 18 months after stage two surgery. This eye was lost in spite of aggressive intervention. The use of temporary keratoprostheses and vitrectomy endoscopes during surgery was necessary in most of these eyes. Conclusions: OOKP surgery presents challenges for the vitreo-retinal colleague. Assessment of the anatomical and functional integrity of the retina prior to and often after OOKP surgery is hampered. An accurately interpreted b-scan ultrasound examination provides the most useful information. Vitreo-retinal surgical intervention is technically demanding and requires the use of temporary keratoprostheses and endoscopes. An individualized and realistic management strategy has to be derived for patients with vitreo-retinal pathology when OOKP surgery is embarked upon.

Purpose: The management of severe ocular surface diseases and end-stage dry eye disorders such as Stevens Johnson syndrome, ocular cicatricial pemphigoid and chemical burns with conventional keratoplasty or keratolimbal allografting remains unsatisfactory. The Osteo-Odonto Keratoprosthesis (OOKP) is a form of keratoprosthesis (artificial cornea) surgery designed to treat the most severe of these cases, and good outcomes with long-term retention have been reported. We present the moderate-term clinical results of Asian patients who have had this device implanted within our Singapore OOKP Program. Methods: OOKP surgery involves a radical two-stage procedure – in stage 1, an autologous canine tooth is removed, modified to receive an optical PMMA cylinder, and implanted into the cheek. The entire ocular surface is denuded and replaced with a full thickness buccal mucosal graft. Stage 2 surgery, performed 2-4 months later, involves retrieval of the tooth-cylinder complex and implanting it into the cornea, after lifting of the buccal mucosal flap, corneal trephination, iris and lens removal and anterior vitrectomy. Concurrent glaucoma and vitreo-retinal procedures may also be performed at either stage, if required. Indications for OOKP surgery include bilateral severe blindness, not amenable to keratoplasty or ocular surface transplantation or with previous failed attempts. Results: In February 2004, the Singapore National Eye Centre embarked on its OOKP program, in collaboration with the National Dental Centre. We have now performed OOKP surgery on 22 patients, with the longest follow-up being 39 months. Of 16 patients with a mean of 19.1 months follow-up (range 5-39 months), no major keratoprosthesis-related complications have occurred, with full anatomical stability and retention in all cases. 73.3% of patients attained at least 6/12 or better vision, while 90% attained 6/6 vision, and remaining patients have attained, and retained their best visual potential with the exception of one patient who lost vision unrelated to the KPro device (endophthalmitis following glaucoma surgery occurred 1 year after KPro surgery). Conclusions: OOKP surgery appears to be a highly promising procedure which has the potential to restore excellent vision to the most severe cases of end-stage corneal disease, when all else has failed. Longer follow-up of these cases is currently underway.

Purpose: This presentation is meant for the keratoprosthesis session organized by Christopher Liu. The early technique for "osteo-odonto-keratoprosthesis" described first by Strampelli in 1963 is demonstrated converting the inclusion of an acrylic prosthesis into an "heterotopic autoplastic transplantation" for the management of chemical and thermal burns, autoimmune disease (Stevens-Johnsons, Lyell), trachoma or pemphigoid scarring, etc. Methods: The surgery comprises three phases. Phase 1: Superficial keratectomy, cleaning and repair of the ocular surface and the fornices and transplantation of buccal mucosa from the internal lip onto the ocular surface. Phase 2: Removal of a superior canine surrounded by dentine and bone. After shaping an adequate lamina of tooth and bone a central trephination is performed to receive the optical PMMA cylinder which is glued into place with dental glue. Then the entire block is placed into the inferior orbital space for biointegration. Phase 3 consists in removal of the osteo-odonto-keratoprosthesis from the orbital socket, dissection of the buccal mucosa, central trephination of the host cornea and fixation of the osteo-odonto.keratoprosthesis into the corneo-scleral bed. Results: Some results and variations of the early technique are illustrated and discussed. Conclusions: Although the technique was primitive and complicated, Strampelli's idea to use autoplastic tissue to incorporate the artificial prothesis into the ocular surface has to be coinsidered of great importance for the evolution of modern techniques of keratoprosthesis implantation.

Purpose: To report the indications, practices, complications, and outcomes from the first multi-center study on the Boston Type 1 Keratoprosthesis. Methods: We analyzed 218 Boston Type 1 Keratoprosthesis surgical procedures, from 20 surgical sites, implanted from January 2003 through August 2007 in 210 eyes of 205 patients. Forms reporting seventy pre-, intra-, and post-operative parameters were collected and analyzed at a central data collection site (Cornea Consultants of Albany, PLLC, Albany Medical College, Albany, NY). The main outcome measures were; Visual acuity and keratoprosthesis survival. Results: Common preoperative diagnoses were graft rejection in 103 eyes (47%) (average prior grafts: 2.24), chemical injury (26 eyes, 12%), bullous keratopathy (34 eyes, 16%), and herpes simplex virus keratitis (12 eyes, 6%). Additionally, 100 eyes (46%) had preoperative glaucoma. Preoperative best-corrected visual acuity ranged from 20/100 to light perception, and was less than 20/200 in 94% of eyes. At an average follow-up of 9.4 months, postoperative vision improved to ≥ 20/200 in 63%. Among eyes at least 1 year postoperative (104 eyes), vision was ≥ 20/200 in 58% of eyes and ≥ 20/40 in 17%. At an average follow-up of 9.4 months, graft retention was 96%. Severe visual loss or failure to improve from keratoprosthesis was usually secondary to comorbidities such as advanced glaucoma, macular degeneration, or retinal detachment. Conclusions: The Boston Type 1 Keratoprosthesis seems to be a viable option after multiple failed corneal grafts or in some situations with a poor prognosis for primary penetrating keratoplasty.

Background: The report presented is an update on continuing development work on modified PHEMA core-and-shirt KPros in animals. Methods: Two variations (improved wet-eye, and dry-eye) of a prototype core-and-skirt Chirila KPro are described. The clinical success rate on implantation of these versions of the Chirila KPro was assessed. Results: It was found that a significant improvement in retention rate was shown in the improved model but that the dry-eye model failed early in two of the three implanted. Conclusions: The significance of the improved strength and the reasons for disappointing results with the early dry-eye KPros are discussed. Ongoing work is briefly outlined.