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Purpose: To investigate the short-term results and performance of a modified Boston keratoprosthesis device manufactured by the Ophthalmic Research Center (ORC-KPro) in patients with end-stage corneal blindness. Methods: This prospective interventional case series was conducted on patients with corneal blindness who were candidates for KPro. The inclusion criterion comprised patients with a bestcorrected visual acuity (BCVA) of less than 20/200 in both eyes, in whom the main reason for vision loss was corneal pathology. The ORC-KPro was implanted using the method previously described for Boston KPro. Results: This study focused on 12 eyes of 12 patients with an average age of 45.9 ±16.8 (range, 19 to 70) years. Eleven patients were male. The KPro indication was corneal blindness due to chemical burns in nine patients (75%) and failure of multiple previous corneal grafts in three patients (25%). Anatomical success was achieved in all patients. The preoperative BCVA was light perception (LP) in 10 eyes and hand motion in 1 eye. Except for one patient who was diagnosed with grade C proliferative vitreoretinopathy during the surgery, the vision of all other patients (91.6%) improved after surgery. The retroprosthetic membrane (RPM) was formed in two eyes (18.1%) after six months. Of the 12 patients, 10 (83.3%) were under treatment with two antiglaucoma medications before surgery. The intraocular pressure of three eyes (25%) was estimated to be high by tactile palpation; however, it decreased in two eyes to the acceptable range. One patient underwent retinal surgery due to total retinal detachment, and two patients (16.7%) underwent vitrectomy due to endophthalmitis. Conclusion: The current study showed that, in the short term, the use of ORC-KPro achieved favorable anatomical success in patients with corneal blindness. However, the functional success rate was limited by the low visual potential due to advanced glaucoma in most patients. [ABSTRACT FROM AUTHOR]

The inner structures of the eye are protected by the cornea, which is a transparent membrane exposed to the external environment and subjected to the risk of lesions and diseases, sometimes resulting in impaired vision and blindness. Several eye pathologies can be treated with a keratoplasty, a surgical procedure aimed at replacing the cornea with tissues from human donors. Even though the success rate is high (up to 90% for the first graft in low-risk patients at 5-year follow-up), this approach is limited by the insufficient number of donors and several clinically relevant drawbacks. Alternatively, keratoprosthesis can be applied in an attempt to restore minimal functions of the cornea: For this reason, it is used only for high-risk patients. Recently, many biomaterials of both natural and synthetic origin have been developed as corneal substitutes to restore and replace diseased or injured corneas in low-risk patients. After illustrating the traditional clinical approaches, the present paper aims to review the most innovative solutions that have been recently proposed to regenerate the cornea, avoiding the use of donor tissues. Finally, innovative approaches to biological tissue 3D printing and xenotransplantation will be mentioned. [ABSTRACT FROM AUTHOR]

Corneal disease and damage can arise from various causes, including infections, corneal dystrophies, trauma and improper contact lens use. These factors can lead to corneal blindness which greatly decreases the patient’s quality of life. Although corneal transplantation is a viable treatment option for many patients, the risk of rejection after corneal transplantation remains a concern. Severe corneal damage requires special methods of treatment, which are still sought after. This narrative review aims to summarize the use of stem cells and keratoprosthesis in the treatment of corneal diseases. Stem cell therapy, particularly limbal stem cell transplantation, shows promise in corneal regenerative therapy, especially the treatment of limbal stem cell deficiency. Additionally, induced pluripotent stem cells have been successfully used in cornea transplantation, offering a novel approach to restoring vision in patients with corneal diseases. Keratoprosthesis, such as the Boston keratoprosthesis and osteo-odonto-keratoprosthesis, provides an alternative for patients who cannot undergo traditional corneal transplantation. Artificial prostheses are also an alternative to corneal transplantation in cases of extensive trauma or in the absence of donor tissue. Continued research and development in stem cell therapy and keratoprosthesis hold the potential to improve the outcomes, accessibility of corneal disease treatment and reducing the global burden of corneal blindness.

Keratoprosthesis (Kpro) evolution over the years has been remarkable from initially rejected due to devastating complication to the present with development of multiple biocompatible materials and acceptable designs. Its indications have expanded beyond recurrent immunologic rejection to include other conditions such as chemical injury and other causes of bilateral limbal stem cell deficiency, extensive corneal neovascularization, neurotrophic corneas, and hypotony. Since then, it is accepted worldwide by many cornea specialists and now has become a standard procedure. Improvement in pre-operative, intra-operative, and post-operative management has resulted in favorable outcomes with reduction in complications. However, sight-threatening complications are even now reported in auto-immune and cicatrizing conditions, which requires prompt management and frequent follow-ups. Researchers in the field have been recently working on improving the design of the currently available devices by introducing the use of new materials that are more biocompatible with the eye. This review article gives an update on recent research in the field, indications, types, and comprehensive detail on outcomes with Kpro.

Abstract Purpose: To investigate the short-term results and performance of a modified Boston keratoprosthesis device manufactured by the Ophthalmic Research Center (ORC-KPro) in patients with end-stage corneal blindness. Methods: This prospective interventional case series was conducted on patients with corneal blindness who were candidates for KPro. The inclusion criterion comprised patients with a best-corrected visual acuity (BCVA) of less than 20/200 in both eyes, in whom the main reason for vision loss was corneal pathology. The ORC-KPro was implanted using the method previously described for Boston KPro. Results: This study focused on 12 eyes of 12 patients with an average age of 45.9 ± 16.8 (range, 19 to 70) years. Eleven patients were male. The KPro indication was corneal blindness due to chemical burns in nine patients (75%) and failure of multiple previous corneal grafts in three patients (25%). Anatomical success was achieved in all patients. The preoperative BCVA was light perception (LP) in 10 eyes and hand motion in 1 eye. Except for one patient who was diagnosed with grade C proliferative vitreoretinopathy during the surgery, the vision of all other patients (91.6%) improved after surgery. The retroprosthetic membrane (RPM) was formed in two eyes (18.1%) after six months. Of the 12 patients, 10 (83.3%) were under treatment with two antiglaucoma medications before surgery. The intraocular pressure of three eyes (25%) was estimated to be high by tactile palpation; however, it decreased in two eyes to the acceptable range. One patient underwent retinal surgery due to total retinal detachment, and two patients (16.7%) underwent vitrectomy due to endophthalmitis. Conclusion: The current study showed that, in the short term, the use of ORC-KPro achieved favorable anatomical success in patients with corneal blindness. However, the functional success rate was limited by the low visual potential due to advanced glaucoma in most patients.

Background: Boston Keratoprosthesis Type I (BI-KPro I) is a synthetic cornea that can be used to restore vision in patients with corneal blindness. This retrospective study evaluated the outcomes of BI-KPro implantation in 118 patients. Material: The mean age of the patients was 56.76 ± 14.24 years. Indications for keratoprosthesis implantation were as follows: graft failure, 47 (39.83%); ocular burn, 38 (32.20%); neurotrophic keratopathy, 11 (9.32%), mucous membrane pemphigoid 9 (7.67%); autoimmune, 6 (5.08%); Stevens–Johnson syndrome, 4 (3.39%); and aniridia (2.54%). Methods: The surgeries were performed between March 2019 and June 2022 at a single clinical center in two locations. The postoperative visual acuity, complications, and need for additional surgical procedures were analyzed. Results: The Best Corrected Visual Acuity before surgery was 0.01 ± 0.006. After one year (V1), it was 0.30 ± 0.27; at two years (V2), it was 0.27 ± 0.26; and at three years (V3), it was 0.21 ± 0.23. The percentage of patients with visual acuity better than 0.1 on the Snellen chart was 37.29% after 1 year, 49.35% after 2 years, and 46.81% after 3 years of follow up. The most common complications were glaucoma (78 patients; 66.1%), corneal melting (22 patients; 18.6%), and retroprosthetic membranes (20 patients; 17.0%). Conclusions: The BI-KPro can significantly improve visual acuity. The worst long-term results were obtained in the group of patients with autoimmune diseases; therefore, careful consideration should be given to implanting BI-KPro in this group. The high incidence of de novo glaucoma or the progression of pre-existing glaucoma suggests the need for careful monitoring. [ABSTRACT FROM AUTHOR]

Peters' anomaly (PA) is a manifestation of complex disorders in the development of the anterior segment of the eye. The most recognizable feature of the disease is a doughnut-shaped central corneal opacity and adhesions between the opacity and underlying iris. Glaucoma is observed in 30–70% of patients, with up to 50% of the patients showing concomitant vision-threatening disorders. Up to 60% of patients have systemic abnormalities or developmental delays. Being a rare malformation, PA is one of the most common congenital indications for corneal transplantation in infants. Penetrating keratoplasty is used as the primary method of treatment in cases with corneal opacification of a degree that forbids visual development in both eyes. The heterogeneity of co-occurring ophthalmic and systemic malformations in the spectrum of PA determines the wide range of success, defined by various endpoints: graft clarity or visual acuity. Although surgical advancement has made corneal grafting possible in younger children, it has a higher graft failure rate and worse visual prognosis than adult keratoplasty. Optical sector iridectomy, pupil dilation, or cornea rotation can alternatively be performed. Satisfying results of pediatric keratoprosthesis in particular cases of PA have been described. Postoperative treatment of PA aims to maintain a clear optical pathway and prevent amblyopia. This article therefore aims at reporting the ophthalmic treatment and need for multidisciplinary management of PA, including pharmacological and surgical treatment. [ABSTRACT FROM AUTHOR]

Purpose: To describe the long-term outcome of the use of a specialized scleral lens known as a prosthetic replacement of the ocular surface ecosystem (PROSE) device to support the ocular surface in patients with a Boston Keratoprosthesis (KPro) Type I. All patients in this series were unable to pursue continuous wear of a bandage soft contact lens (BSCL) – a critical aspect of post KPro implantation management intended to protect the corneal carrier tissue from desiccation and stromal melting. Observations: Four eyes of four patients with a Boston KPro Type I were included. All four had failed BSCL wear and were instead treated with PROSE device wear. All four patients had underlying diagnoses associated with a diseased ocular surface (Stevens-Johnson Syndrome [one patient], prior failed penetrating keratoplasty associated with herpes zoster-related neurotrophic keratopathy [one patient], and prior failed penetrating keratoplasty associated with severe dry eye disease [two patients]). Causes of failure of BSCL wear included poor retention, discomfort, and poor vision. PROSE device wear was initiated on average seven and a half (range four to 14) months post-KPro implantation. The wear schedule varied and ranged from waking-hour wear only to 24-h wear. The average duration of device wear was 59.3 (range 28–103) months. Two patients exhibited persistent corneal epithelial defect formation with waking-hour wear, which resolved within 10 days with 24-h device wear. All patients exhibited improvement in vision with PROSE compared to baseline, averaging six and a half (range six to eight) lines of improvement in Snellen acuity, and all patients reported increased comfort. There was no incidence of microbial keratitis, KPro device instability, or other complication throughout the duration of device wear. Conclusions and Importance: This report offers a novel alternate approach to long-term support of the ocular surface in patients with a Boston KPro who fail standard continuous BSCL wear.

The inner structures of the eye are protected by the cornea, which is a transparent membrane exposed to the external environment and subjected to the risk of lesions and diseases, sometimes resulting in impaired vision and blindness. Several eye pathologies can be treated with a keratoplasty, a surgical procedure aimed at replacing the cornea with tissues from human donors. Even though the success rate is high (up to 90% for the first graft in low-risk patients at 5-year follow-up), this approach is limited by the insufficient number of donors and several clinically relevant drawbacks. Alternatively, keratoprosthesis can be applied in an attempt to restore minimal functions of the cornea: For this reason, it is used only for high-risk patients. Recently, many biomaterials of both natural and synthetic origin have been developed as corneal substitutes to restore and replace diseased or injured corneas in low-risk patients. After illustrating the traditional clinical approaches, the present paper aims to review the most innovative solutions that have been recently proposed to regenerate the cornea, avoiding the use of donor tissues. Finally, innovative approaches to biological tissue 3D printing and xenotransplantation will be mentioned.

Corneal melt is a sight-threatening complication of Boston type 1 keratoprosthesis (KPro). Severe corneal melt may result in hypotony, choroidal hemorrhage, and even spontaneous extrusion of the KPro, which may lead to a poor visual prognosis. Lamellar keratoplasty is one surgical option for the management of mild corneal melt, especially when a new KPro is not available. Herein, we present a new surgical technique application, intra-operative optical coherence tomography (iOCT) for the management of cornea graft melt after Boston type 1 KPro implantation. The visual acuity and the intra-ocular maintained stable at 6 months post-operatively, and the KPro remained in place without corneal melting, epithelial ingrowth, or infection. iOCT may prove to be a real-time, non-invasive, and accurate treatment for corneal lamellar dissection and suturing beneath the anterior plate of the KPro, which can effectively help the surgeon to make surgical decisions and reduce post-operative complications. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the impact of Boston Type I Keratoprosthesis (BI-Kpro) implantation on retinal and visual pathway function, respectively, assessed by full-field electroretinography (ERG) and visually evoked potentials (VEPs). Methods : This is a prospective interventional longitudinal study, and patients with BI-Kpro implantation were assessed preoperatively and at 3 and 12 months after surgery. ERG, flash, and pattern-reversal VEPs (15' and 60' checks) along with visual acuity (VA) were performed. Results: A total of 13 patients (24 to 88 years of age) were included. Mean baseline VA (logMAR) improved from 2.30 to 1.04 at 3 months and to 1.00 at 12 months. Flash VEPs were normal in 6 (46%) patients and in 10 (77%) patients at the 12-month follow-up. PVEP was non-detectable in all patients preoperatively for both check sizes. For 15' check size, 6 (46%) patients showed responses after 3 and 12 months except for 1 patient with normal responses at 12 months with the remaining non-detectable. For 60' checks, 11 (85%) patients had responses 3 months after surgery with only 9 (70%) showing responses at 12 months. Abnormal full-field ERGs were found in all patients preoperatively. Amplitude improvement was found in 10 (77%) patients from baseline to 3 months and in 8 (62%) patients from the 3- to the 12-month follow-up. Conclusions: In this small cohort of patients with BI-Kpro implantation, a remarkable improvement on visual function quantitatively assessed by electrophysiological testing was found in the majority of cases. Visual electrophysiological testing can contribute to objectively assess functional outcomes in this population. [ABSTRACT FROM AUTHOR]

Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens–Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren's syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed.

Background and Aims Blindness is one of the major health problems and diseases, such as corneal opacity, cataracts, glaucoma, and age-related macular degeneration due to diabetes are recognized as the most important causes of bilateral blindness worldwide. Among these factors, corneal diseases are considered as an important cause of blindness. The aim of this study was to review the prevalence, causative agents, treatment methods, and also the use of keratoprosthesis or artificial cornea as the last option to restore vision to blind patients with severe corneal injuries.Methods Studies related to the subject were collected and reviewed using valid databases, such as PubMed and Google Scholar. Results Out of more than 1000 articles in the field of the artificial cornea, about 70 related articles were selected and reviewed.Conclusion Generally, keratoprosthesis is used for patients for whom corneal transplantation is not possible or the risk of corneal transplantation rejection is high. The patient’s current condition and the outcome of the patient’s anterior and posterior segment examinations, previous treatments and surgeries, and the medications used should be considered. If a person has advanced retinal disease or glaucoma, he/she is not a good candidate for keratoprosthesis. If the patient’s vision in either eye is within the range of light perception or hand movement detection, while the optic nerve and macula are healthy, it is appropriate to use keratoprosthesis. It can be said that there is still no type of keratoprosthesis that can be used without side effects and for all patients in need, but researchers are still trying to improve the quality of keratoprostheses, which can restore patients’ lost vision with minimal complications.

To evaluate the relationship between penetrating keratoplasty (PK) and postoperative PRA level and number of unacceptable antigens. A cross-sectionalstudy was performed on patients with history of PK. Patients with prior solid organ transplantation, pregnancy, or blood transfusion were excluded. These findings were combined with a retrospective review. Patients were grouped by single or multiple PKs. The primary outcome was postoperative PRA level. Incidence of postoperative PRA elevation and mean peak PRA was higher in the multiple PK group (p =.08 and p =.010, respectively). Mean number of unacceptable antigens was elevated in the multiple PK group (p =.024). There was a moderately positive correlation between number of PK grafts and PRA level (r = 0.629, p =.0002). PRA level may be influenced by PKs, with higher PRA associated with increased prior PKs. Further studies are necessary to determine the potential prognostic value. Abbreviations: PK: penetrating keratoplasty; PRA: panel reactive antibodies; OSST: ocular surface stem cell transplantation; LSCD: limbal stem cell deficiency [ABSTRACT FROM AUTHOR]

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Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens–Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren’s syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed. [ABSTRACT FROM AUTHOR]

Introduction: This report describes the use of conjunctival flaps to enable the survival of type I keratoprosthesis (KPro) in two cases of bilateral severe total limbal stem cell deficiency (LSCD) following chemical burns. Presentation of case: Two patients had a history of bilateral chemical injury with lime. On examination, the presenting vision was light perception to hand motions and both cases had conjunctivalized ocular surfaces with symblepharon. A modified technique of type I keratoprosthesis was used, where the conjunctivalized corneal pannus was dissected and lifted off as an inferior fornix-based conjunctival flap. This was followed by a standard surgical technique of type I KPro. The flap was then secured over the device and optical opening was made two weeks later. Both the patients had stable ocular surfaces with visual acuity of 20/20 at 2–7 years of follow-up. Discussion: In patients with total LSCD with adnexal involvement, type I KPro has unsatisfactory long-term survival because of the risk of repeated epithelial breakdowns and stromal ulceration. With the innovative approach described in this report, type I KPro can be successfully used for sustainable visual improvement in the presence of severe ocular surface disease and symblepharon. Conclusion: Conjunctival flaps can be used along with type I KPros to improve long-term survival and give sustainable visual outcomes in cases of bilateral corneal blindness due to advanced ocular surface damage.

Mucous membrane pemphigoid (MMP) with ocular involvement, also referred to as ocular cicatricial pemphigoid, is a rare, autoimmune blistering disease that can have devastating effects for patients. The resulting corneal neovascularization, recurrent corneal abrasions, and ulceration can ultimately result in severe vision loss. We present a 64-year-old man with recalcitrant ocular MMP and consequently advanced corneal involvement that received bilateral keratoprostheses. This case highlights an aggressive but successful placement of bilateral keratoprostheses in recalcitrant ocular MMP, which restored his vision and ultimately his quality of life.

Introduction: Corneal disease is a leading cause of blindness globally that stems from various etiologies. High-throughput platforms that can generate substantial quantities of corneal grafts will be invaluable in addressing the existing global demand for keratoplasty. Slaughterhouses generate substantial quantities of underutilized biological waste that can be repurposed to reduce current environmentally unfriendly practices. Such efforts to support sustainability can simultaneously drive the development of bioartificial keratoprostheses.Methods: Scores of discarded eyes from the prominent Arabian sheep breeds in our surrounding region of the United Arab Emirates (UAE) were repurposed to generate native and acellular corneal keratoprostheses. Acellular corneal scaffolds were created using a whole-eye immersion/agitation-based decellularization technique with a widely available, eco-friendly, and inexpensive 4% zwitterionic biosurfactant solution (Ecover, Malle, Belgium). Conventional approaches like DNA quantification, ECM fibril organization, scaffold dimensions, ocular transparency and transmittance, surface tension measurements, and Fourier-transform infrared (FTIR) spectroscopy were used to examine corneal scaffold composition.Results: Using this high-throughput system, we effectively removed over 95% of the native DNA from native corneas while retaining the innate microarchitecture that supported substantial light transmission (over 70%) after reversing opacity, a well-established hallmark of decellularization and long-term native corneal storage, with glycerol. FTIR data revealed the absence of spectral peaks in the frequency range 2849 cm−1 to 3075 cm−1, indicating the effective removal of the residual biosurfactant post-decellularization. Surface tension studies confirmed the FTIR data by capturing the surfactant’s progressive and effectual removal through tension measurements ranging from approximately 35 mN/m for the 4% decellularizing agent to 70 mN/m for elutes highlighting the effective removal of the detergent.Discussion: To our knowledge, this is the first dataset to be generated outlining a platform that can produce dozens of ovine acellular corneal scaffolds that effectively preserve ocular transparency, transmittance, and ECM components using an eco-friendly surfactant. Analogously, decellularization technologies can support corneal regeneration with attributes comparable to native xenografts. Thus, this study presents a simplified, inexpensive, and scalable high-throughput corneal xenograft platform to support tissue engineering, regenerative medicine, and circular economic sustainability.

Corneal transplantation constitutes one of the major treatments in severe cases of corneal diseases. The lack of cornea donors as well as other limitations of corneal transplantation necessitate the development of artificial corneal substitutes. Biosynthetic cornea model using 3D printing technique is promising to generate artificial corneal structure that can resemble the structure of the native human cornea and is applicable for regenerative medicine. Research on bioprinting artificial cornea has raised interest into the wide range of materials and cells that can be utilized as bioinks for optimal clarity, biocompatibility, and tectonic strength. With continued advances in biomaterials science and printing technology, it is believed that bioprinted cornea will eventually achieve a level of clinical functionality and practicality as to replace donated corneal tissues, with their associated limitations such as limited or unsteady supply, and possible infectious disease transmission. Here, we review the literature on bioprinting strategies, 3D corneal modelling, material options, and cellularization strategies in relation to keratoprosthesis design. The progress, limitations and expectations of recent cases of 3D bioprinting of artifial cornea are discussed. An outlook on the rise of 3D bioprinting in corneal reconstruction and regeneration is provided.

Background:   Corneal afflictions may result in blurred vision, but in severe cases it can cause complete vision loss. In many cases, sight can be restored through a corneal transplant using donor tissues. The problem with transplantation by using donor tissues is the lack of cornea tissues available and a risk of rejection. NanoCurv Impressions has developed a one-piece state of the art artificial corneal device with nanopattern technology. Research is in progress to validate the efficacy of the nanostructures which should improve device integration and prevent infections.

AIM: To investigate the safety of vitreoretinal surgery when using a soft contact lens as a temporary keratoprosthesis (TKP) in patients with severe corneal opacifications. METHODS: Three patients with simultaneous corneal and vitreoretinal pathology were treated with a soft contact lens that was used as a TKP to facilitate vitreoretinal surgery. The soft contact lens was fixated with sutures onto the globe so that no leakage was possible. RESULTS: Vitreoretinal surgery with excellent fundus view was possible in all cases. The soft contact lens allowed safe central and peripheral vitrectomy. Surgery was successful in all cases. CONCLUSION: A soft contact lens properly fixated on the globe can successfully replace a TKP. This surgical procedure has several advantages like one size fits all, low costs, and easy access to the material.

Thomas John,1,2,* Sean Tighe,3,4,* Hosam Sheha4,5,* 1Thomas John Vision Institute, Tinley Park, IL, USA; 2Department of Ophthalmology, Loyola University at Chicago, Maywood, IL, USA; 3Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, USA; 4Department of Ophthalmology, Florida International University Herbert Wertheim College of Medicine & Glaucoma Research Organization, Miami, FL, USA; 5Department of Ophthalmology, Manhattan Eye, Ear, and Throat Hospital, Hofstra Northwell School of Medicine, New York, NY, USA*These authors contributed equally to this workCorrespondence: Hosam ShehaManhattan Eye, Ear, and Throat Hospital, 210 East 64th Street, New York, NY, 10065, USATel +1 917-810-9555Email Hoss88@gmail.comSean TigheDepartment of Ophthalmology, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USATel +1 813-690-0099Email seanthomastighe@gmail.comAbstract: Corneal melt remains a challenging complication of Boston keratoprosthesis (KPro) and may lead to disastrous consequences such as endophthalmitis, KPro extrusion, and permanent loss of vision. Several procedures have been suggested to repair established melts; however, KPro removal or exchange is often required due to high recurrence. We herein describe a novel surgical technique to repair corneal melt: a lamellar corneal graft is centrally trephined, and a radial cut is extended from the central opening to create a keyhole graft. The graft is draped around the KPro and tightly secured around the central stem. The radial cut is closed with sutures, and the graft is secured into the underlying tissue with fibrin glue and sutures. The graft remains stable with the KPro in place, while the patients maintain a 20/200 vision or better at two years. This technique is a useful alternative for securing KPro and preventing corneal melt recurrence.Keywords: corneal melt, keratoprosthesis, lamellar keratoplasty

The exceptional adhesive properties of polydopamine (PDA) and its ability to perfectly fix various biomolecules and metal ions are conducive for the development of appropriate modifications of implant surfaces. Over the recent years, several combinations of different substrates and surface modification molecules and/or ions have been tested effectively with PDA. In addition, a number of these combinations were proved to have good biocompatibility and specific functions. Therefore, this article summarizes the latest developments in implant surface modification using PDA, in various fields ranging from orthopedics and dentistry to corneal and cardiovascular implants. In addition to osteogenesis, the antibacterial and anti-inflammatory functions of PDA-coated surfaces are also discussed. These studies suggest that PDA, which has strong adhesive properties and good biocompatibility, has potential for use in the surface modification of a variety of functional implants. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: to evaluate the results of spontaneous non-penetrating keratoprosthesis with a Fedorov — Zuev prosthesis in a patient with severe chemical burns in both eyes. Material and methods.Patient K., 38, who had sustained a severe burn injury in the past and numerous reconstructive plastic operations on both eyes (amniotic tissue implantation, allolymbal transplantation, layer-by-layer and penetrative keratoplasty, cataract extraction with IOL implantation, total auto-conjunctival corneal plastic surgery) with no functional effect, was subjected to a multi-stage keratoprosthesis of the left eye according to the method practiced by the Helmholtz National Medical Research Center of Eye Diseases. Results.After one of the stages (implantation of the haptic part of the keratoprosthesis with a temporary cylindrical plug), an aseptic necrosis of the tissue above the cylinder occurred. As a result, an unexpected functional effect was revealed: visual acuity of the operated eye 0.02 sph -20.0 D = 0.2. During a dynamic follow-up that lasts 2.5 years, visual acuity remains stable, and the corneallayers behind the cylinder retain transparency. During this time, all stages of keratoprosthesis were performed on the fellow eye with a functional result of 1.0. Conclusion. The long-term result of spontaneous non-penetrating keratoprosthesis indicates the need to study the prospects and develop a method of non-penetrating keratoprosthesis with a Fedorov — Zuyev prosthesis.

Infectious keratitis develops in 13.6% of eyes after keratoprosthesis (Kpro) implantation, with a similar rate of culture-positive bacterial and fungal keratitis. We report a case of 73-year old man who underwent Boston Kpro implantation in the left eye 2 years back. He presented with conjunctival discharge and a whitish growth over the bandage contact lens (BCL) for the past 2 weeks. Slit-lamp examination showed a whitish elevated growth with surrounding diffuse brownish feathery seeding all over the BCL. The BCL which was sent for culture grew fungus. The underlying Kpro was clear with no evidence of any active infiltrate. The patient was started on topical antifungal eye drops and was followed up for 12 months with no recurrence of infection. Educating the patient to be sensitive and to report immediately if they note any abnormality is as important as cleaning or replacing the BCL on a regular basis.

Introduction: This study aimed to evaluate the surgical treatment results for conjunctival limbal autograft (CLAU) and keratolimbal allograft (KLAL) in various types of limbal stem cell deficiency (LSCD) etiologies performed in order to achieve a stable ocular surface prior to KPro implantation. Methods: We analyzed the outcomes of the surgical treatment of 43 eyes of 39 patients with LSCD as an initial treatment preparing patients' ocular surface for KPro implantation. The most common causes were ocular trauma (50.7%), mainly alkali burns (77%); autoimmune causes, mainly ocular cicatricial pemphigoid (OCP; 17.4%); infection (15.9%) including Lyell's syndrome/Stevens–Johnson syndrome (LS/SJS; 16%). In all 17 eyes operated on with CLAU, this procedure was performed once. Similarly, one uncomplicated KLAL procedure in one eye was performed in 10 women and 19 men. In another one woman and three men, KLAL was performed in both eyes. In one man with Lyell's syndrome, the KLAL operation was performed three times in one eye. Follow-up was at least 12 months. Results: Visual acuity (VA) improved in 17 eyes (31%) and remained unchanged in 38 eyes (69%). VA improved from light perception to hand movements in three eyes (16%) from the CLAU group of patients and eight eyes (15%) from the KLAL group; VA improved from hand movements to finger counting in two eyes (12%) post CLAU and two eyes (4%) post KLAL operation. The most common complication of surgical treatment was persistent epithelial defect that was refractory to medical treatment in 32 eyes (58%), 5 eyes post CLAU and 27 post KLAL. Corneal conjunctivalization (19%) and neovascularization (29%) were present on the corneal edge of the graft. Symblephara recurred within 3 months in nine eyes (17.3%) after KLAL, including four eyes that had been chemically burned and five eyes with LS/SJS. Discussion: Pretreatment with CLAU or KLAL procedures in severely damaged ocular surfaces allows the ocular surface to be prepared for safe KPro implantation with sufficient tissue surroundings with less conjunctivalization and deeper conjunctival fornices. [ABSTRACT FROM AUTHOR]

Boston Keratoprosthesis Type 1 (KPro), an artificial cornea, is a therapeutic option for patients in need of corneal transplantation when the prognosis of traditional keratoplasty is guarded. Bandage contact lens wear is essential in the post-operative management of KPro eyes in order to maintain adequate corneal graft hydration, and minimize the risk of adverse complications. Suitable bandage contact lens selection is imperative to preserve keratoprosthesis function, and customized modifications of contact lens parameters may be necessary to ensure adequate fitting. The available contact lens options, modifications, and protocols for the continued care of Boston Keratoprosthesis are discussed. A simple, yet unreported modification for contact lenses fit over KPro eyes in the setting of ocular surface irregularities is proposed, which may hold clinical utility when fitting keratoprosthesis patients with scleral elevations and glaucoma filtration devices. [ABSTRACT FROM AUTHOR]

Abstract This short report includes 5 eyes of 5 patients (mean age 63.2 ± 12 years) who underwent a tectonic keratoplasty [deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PK)] in order to rehabilitate the eye after the extrusion of the non-perforating keratoprosthesis (Kpro) KeraKlear (KeraMed, USA). The non-perforating Kpro was extruded after a mean period of 21.4 ± 21.8 months due to melting. In two cases, the keratoplasty was performed the same day of the non-perforating Kpro removal due to a severe melting, while in the other three cases it was performed one to 3 months later. Two eyes received a DALK, but in 3 eyes a macroscopic Descemet membrane perforation forced the conversion into a PK. The mean follow-up period after the keratoplasty was 16.8 ± 6.6 months. No cases of rejection were recorded. All the 5 eyes achieved “anatomical success” (transparent graft, with no signs of infection or inflammation). Two eyes showed limited “functional success” because the achievement of the best visual potential was prevented by the development of glaucomatous optic atrophy during the follow-up period. In conclusion, this short report presents an unexpected success of a keratoplasty performed with a tectonic purpose after the extrusion of the non-perforating Kpro because the corneal graft remained transparent, without neovascularization or scarring during the follow-up period. This initial evidence shows some encouraging results regarding graft survival rate and the achievement of a useful visual rehabilitation with keratoplasty after a non-perforating Kpro failure instead of repeating the Kpro implantation.

We evaluated the visual outcome of combined penetrating keratoplasty (PKP) and 25G pars plana vitrectomy (PPV) performed without a temporary keratoprosthesis or endoscopy in a patient with vitreoretinal disease complicated by severe corneal opacity. The patient was a 68-year-old woman who had severe corneal opacity and silicone oil in her left eye after several previous intraocular surgeries for rhegmatogenous retinal detachment and proliferative vitreoretinopathy. We successfully performed a combined surgery of conventional PKP followed by 25G PPV without the use of a keratoprosthesis.At 6 months after surgery, visual acuity had not improved, and the density of corneal endothelial cells of the donor cornea had declined from 3,205 to 1,969 cells/mm2. However, corneal transparency remained good, and additional surgery for vitreoretinal disease was not necessary. The combined surgical procedure designed to minimize the number of open-sky steps and to limit vitreoretinal complications thus proved to be safe and achieved stable corneal clarity in a patient with vitreoretinal disease and severe corneal opacity.

Purpose The aim of this study was to evaluate the preliminary results of osteo-odonto keratoprosthesis (OOKP) performed in Alexandria Main University Hospital, Alexandria, Egypt in eyes with end-stage cicatrizing conjunctivitis. Patients and methods OOKP surgery was done in two stages. Stage 1 included preparation of the globe, buccal mucous membrane harvesting, and preparation of osteo-odonto alveolar lamina with the cemented optical cylinder. The prepared lamina was then placed in the submuscular space for 2–3 months. In stage 2, the lamina–optical cylinder complex was implanted under the buccal mucous membrane and the posterior part of the optical cylinder was placed in a central corneal opening to act as an artificial cornea, transmitting image to the retina. Results Six eyes with end-stage ocular surface disease were included in this study. Anatomical success, in the form of retention of the prosthesis, was achieved in five eyes. The procedure failed in one eye due to unhealthy canines with a small amount of bone in the lamina. Functional success, defined as restoration of vision, was achieved in four eyes. Visual improvement was not attained in one eye (in addition to the eye with anatomical failure) due to optic atrophy despite good retention of the device. Conclusion OOKP is a promising procedure to regain vision in severe cases of end-stage corneal blindness, unsuitable for cadaveric corneal grafts. Proper selection of cases is crucial to achieve the best anatomical and functional results.

Keratoprosthesis (KPro) is a surgical procedure largely confined to end-stage corneal blindness correction, where artificial cornea substitutes the native tissue. Though the problem of bio integration was addressed partially by strategic utilization of synthetic polymers and native tissue, major challenges like optical performance and design-associated post-operative complications of KPro were overlooked. Herein, a novel intralamellar KPro design is conceptualized to address these challenges using a light-transparent poly(2-hydroxy ethylmethacrylate) (pHEMA) hydrogel with good shape memory. pHEMA-based optics' theoretically modelled refractive surfaces for both phakic and aphakic conditions were investigated against the standard Navarro model and optimized to new aspheric geometries having high optical functionality utilizing the Zemax OpticStudio software. The optical clear aperture size standardized achieved a 15% improvement in the illumination field. The introduction of asphericity on the two refractive surfaces of the optic on both models resulted in substantial improvements in the spot spread confinement on the retina, spatial resolution, and Seidel aberration. The design simulation study shows that the developed materials' optical characteristics coupled with newly optimized refractive surface geometries can indeed deliver very high visual performance. Furthermore, the procedure can be adapted to analyze and optimize the optical performance of a KPro, intraocular lens, or contact lens., (© 2024 IOP Publishing Ltd.)

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. [ABSTRACT FROM AUTHOR]