Glass-metal keratoprosthesis: Light and electron microscopical evaluation of experimental surgery on rabbit eyes

Abstract

A keratoprosthesis (KP) is the last and only surgical resort to regain some visual acuity in eyes with severely damaged corneae. Corneal blindness represents an important percentage of the blind in the economically poor countries. Commercially available KP's, e.g. those made of PMMA, which are difficult to sterilize and vulnerable to surface damage, are too expensive in these countries. To overcome these disadvantages, we developed a new KP, made of a glass core melted into a platinum cylinder with flange. They were implanted unilaterally in eyes of ten Hollander rabbits intralamellarly. They were fixated by two stainless steel traction threads passed around the whole eyeball. We investigated this type of KP in the rabbit cornea, its acceptance by stroma, epi- and endothelium, and its hydro-mechanical dynamics in situ. No signs of infection or extrusion were observed. No epithelial downgrowth, nor adverse tissue reaction could be detected. LM and SEM showed endothelialization of the newly formed stroma around the central column of the KP. We conclude that this type of KP (although optically still to be optimized) has been accepted by the rabbit cornea and a clinical trial on cornea-blind patients is justified.

How can bioactive glasses be useful in ocular surgery?

“…Since then, the use of glass to manufacture the optical core of keratoprostheses was accompanied by controversial results and, after the Second World War (WWII), it was commonly substituted by the lighter PMMA. In recent years, the unique exception has been represented by the “champagne cork” keratoprosthesis, developed by Worst and coworkers in the 1980s . This model had a shape similar to a mushroom and consisted of a glass core mounted in a platinum cylinder provided with a flange, through which four stainless steel wires were passed for the fixation to the sclera .…”

“…In recent years, the unique exception has been represented by the "champagne cork" keratoprosthesis, developed by Worst and coworkers in the 1980s. 27 This model had a shape similar to a mushroom and consisted of a glass core mounted in a platinum cylinder provided with a flange, through which four stainless steel wires were passed for the fixation to the sclera. 28 This keratoprosthesis was initially implanted in a large number of cases in India from the 1980s to the early 1990s with a high rate of success.…”

Cell-ingrowth in a silicone plombe

“…In recent years great improvements have been made in the development and application of biomedical devices for surgical purposes in the human body, such as tracheal and bronchial implants [1], vascular prostheses [2], suturing materials for corneal operations [3], artificial corneas [4], artificial skin [5] and hollow fibres for drug delivery [6]. The improvements are the result of the development and fabrication of new materials and the use of new implant techniques, but our knowledge of the cellular and immune responses to biomaterials is incomplete.…”

Evaluation of stability and biocompatibility of PHEMA-PMMA keratoprosthesis by penetrating keratoplasty in rabbits

“…More than 10 million people suffer from corneal origin blindness throughout the world, making it the second most common eye affliction next to cataracts [23422]. Corneal blindness is caused by various diseases such as ulceration, trauma, vitamin A deficiency, keratitis, dry eye syndrome, and chemical burns [3].…”

“…Corneal blindness is caused by various diseases such as ulceration, trauma, vitamin A deficiency, keratitis, dry eye syndrome, and chemical burns [3]. In most forms of corneal blindness, the successful alternative for visual regain is corneal transplant using donor tissue [10].…”