Coralline hydroxyapatite keratoprosthesis in rabbits

Current keratoprosthesis designs face challenges in achieving long-term integration with host tissues. Prior research has shown that materials lacking biocompatibility or structural similarity to native corneal curvature may lead to complications like extrusion or rejection. No prior work had resolved the issue of long-term tissue integration with a non-biodegradable implant. This gap motivated the development of a new keratoprosthesis material. The need for a biocompatible, porous support remained unmet in clinical settings. Existing studies had not demonstrated sustained integration over extended periods. The role of vascularization in long-term success was not fully understood. This paper's contribution lies in a novel hydroxyapatite-based design. The study's focus on rabbit models reflects the need for preclinical validation.

The aim of this study was to evaluate the performance of a new keratoprosthesis made of porous hydroxyapatite in a rabbit model. The specific problem addressed was the lack of a keratoprosthesis that mimics corneal curvature and supports tissue integration. The motivation stemmed from the high failure rates of existing prostheses due to extrusion or rejection. The study sought to test whether hydroxyapatite could provide biocompatibility and biointegration. The design aimed to allow tissue growth into the implant's structure. The 12-month observation period was chosen to assess long-term outcomes. The use of New Zealand rabbits was based on their suitability for corneal studies. The study tested the hypothesis that hydroxyapatite could support successful integration.

The study used a unilaterally implanted keratoprosthesis in 12 New Zealand rabbits. The device was made of porous hydroxyapatite, chosen for its biocompatibility and non-biodegradability. Implants were placed in the right eyes using an intralamellar technique. A homologous episclerokeratoplasty was performed with and without a conjunctival flap. The implantation was followed by a 12-month observation period. Pathology studies were conducted to assess tissue reactions. Technetium-99 bone scans were used to evaluate vascularization. The study design allowed for both qualitative and quantitative assessments of integration.

The results showed good vascularization around the implanted keratoprosthesis. No signs of infection or extrusion were observed during the 12-month period. There was no epithelial downgrowth into the implant structure. Adverse tissue reactions were not detected in any of the rabbits. The porous hydroxyapatite supported tissue integration without rejection. The absence of complications suggests strong biocompatibility. Technetium-99 scans confirmed successful vascular integration. These findings suggest the keratoprosthesis is suitable for further clinical testing.

The authors concluded that the hydroxyapatite-based keratoprosthesis demonstrated favorable outcomes in the rabbit model. The absence of infection, extrusion, or adverse reactions supports its biocompatibility. The vascularization observed suggests successful integration with host tissues. The lack of epithelial downgrowth indicates a well-designed implant structure. The study's findings suggest the device is safe for further clinical evaluation. The 12-month observation period provided sufficient evidence of long-term stability. The results align with the goal of developing a keratoprosthesis that mimics natural corneal integration. The authors propose that a clinical trial is warranted based on these findings.