Application of Bioceramics in Ophthalmology

Abstract

Bioceramics have a great potential in ophthalmology and these materials were tested and applied in three different fields of ophthalmic surgery: oculoplastic surgery for orbital floor repair, orbital implants for anophthalmic patients and ocular keratoprosthesis (artificial cornea). Currently, Hydroxyapatite (HA), Polyethylene (PA) and Alumina are the most used biomaterials for ocular surgery. In the case of orbital floor repair the implant acts as a bone graft providing structural support at the bone defect site (fracture). Porous bioceramics stimulate fibrovascular in-growth, which is a fundamental feature to stabilize the orbital implant in anophthalmic patients, and also secure an appropriate motility of ocular prosthesis. In the field of keratoprosthesis, bioceramics are mainly used to make a skirt that aims to connect the central optical part of the keratoprosthesis with the host tissue. Recently, many others biomaterials, among them Bioactive glasses (BGs) and Bioactive glass-ceramics (BGCs), have been extensively investigated for applications in ocular surgery. The extraordinary versatility of these biomaterials, which primarily depends on the flexibility of their composition, allows various applications in ophthalmology. It has been suggested recently that BGs and BGCs possess a unique power of stimulating tissue regeneration and cell activity in vivo. BGs and BGCs can make better the performance of ocular implants. Bioactive glasses are a very promising in this field of orbital floor fractures and defect repairment because they are known to bond both to bone and muscle tissue which is the main property for implants used in reconstructive surgery. Furthermore, through the release of adequate ionic dissolution products, porous bioactive glasses can stimulate angiogenesis and fibrovascular in-growth, which are significant to ensure a suitable motility of orbital implants and lower the risk of infections. It was discovered that porous bioactive glasses are able to stimulate the keratocytes adhesion and proliferation, and that ability made them a material that is potentially desirable and a leading candidate for a new and improved kind of keratoprosthesis skirts. Bioactive glasses can be used as devices for the controlled release of therapeutic ions and therapeutic biomolecules. Considering the future, bioactive glasses and glass-ceramics can improve the performance of ocular implants imparting them key extra-functionalities such as antibacterial features via the release of adequate metal ions, controlled drug release, to elicit an angiogenic and anti-inflammatory effect at the implant site.