The idea of replacing opaque corneal tissue with an optical artificial material came more than two centuries before the idea of transplantation.
1,2 Keratoprosthesis (KPro) is indicated in cases of corneal blindness for which conventional treatment with penetrating keratoplasty (PK) has either failed or has a poor prognosis.
3–5 A consistent meta-analysis showed that over the intermediate-term postoperative follow-up period, patients receiving KPro are more likely to achieve improvement in their visual acuity and to retain this improvement than patients undergoing a repeated PK.
6 Much effort has been focused on improving the biocompatibility and clinical performance of KPro.
7,8 Integration of the device with the surrounding cornea is essential to prevent microorganism invasion and has an impact on its safety and efficacy. Polymethyl methacrylate (PMMA) is the most widely material used for the central optical portion of KPro because it is biologically inert, transparent, easy to fabricate, and accommodating of a broad range of optical powers.
Titanium and its alloys can be processed via laser welding using sprayed powder manufacturing in three-dimensional (3D) printing. This method has advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants.
9 Using this technology, the characteristics of the product surface can be controlled to create ideal maximum porosity and roughness, which may increase tissue integration and prevent implantation failure. This process occurs by providing spaces for cells, vascular tissue, and even bone tissue ingrowth to form mechanical interlocking.
10,11
The most widely used device globally is the Boston type I KPro, and the newest model is made of a PMMA optical slab that is fixed to a titanium back plate mounted in a healthy allograft corneal graft as its carrier and support.
4 This prosthesis has proven to be effective in surgical interventions to rehabilitate eyes with severe ocular surface disease, and more than 14,000 devices have been implanted.
5 Unfortunately, because of costs and regulation issues, only 1200 KPro implantations are performed per year worldwide.
7 Moreover, not all countries have a sufficient corneal donor tissue supply or eye bank organizations, particularly in the developing world, which limits the application of this KPro.
8 Therefore, this study presents a novel, low-cost, titanium 3D printing device called the KPro of Brazil (KoBra), which uses recipients’ own corneas as a prosthesis supporter. The goal of this study was to evaluate the retention rate, incidence of postoperative complications, and their management in alkali-burned rabbits.