Boston Keratoprosthesis Type I for corneal blindness

Level of innovation

Two specialists felt that the Boston KPro I has a novel concept and design. One commentator noted that it has a niche in the temporary restoration of vision (for several years) in people for whom conventional corneal transplantation is unsuitable because of the high risk of failure.

Potential patient impact

One specialist noted that corneal allograft transplantation is the standard of care for corneal blindness, but if the first graft fails, further grafts are less likely to be successful in the long term. The likelihood of success is particularly poor in people who have high-risk factors, such as deep neovascularisation, certain co-morbidities (for example, bullous keratopathy), and limbal stem cell failure because of chemical injury, aniridia and ocular surface dysplasias. The commentator felt that the Boston KPro provides a valid alternative to repeat corneal allografts in these people. Also, people for whom systemic immunosuppression is unsuitable will also benefit from the Boston KPro I because it is synthetic and so immunosuppression is not needed.

Although the Boston KPro I may benefit some people, the commentator reflected that the keratoprosthesis procedure is as invasive as PK and people having it need the same follow-up as those having PK because of the lifelong risk of glaucoma and infections such as endophthalmitis.

Potential system impact

Two specialists noted that specialist training would be needed to use Boston KPro I. They agreed that Boston KPro I should only be used in specialist centres with cornea and glaucoma specialist services and would involve long term follow-up by corneal consultants specialising in its implantation and managing of associated complications.

One specialist felt that the Boston KPro I should only be used by experienced corneal surgeons. When the Boston KPro I has to be combined with a glaucoma draining device, surgeons must either have the expertise to implant such a device themselves or should be assisted by a glaucomologist. Another commentator highlighted that using the Boston KPro I might lead to cost savings because although it uses an allograft carrier, it is not of clinical grade and so it costs less than other procedures which need optical grade tissue. Another noted that although it might not lead to cost savings in the NHS, there may be cost savings associated with preventing blindness. One specialist felt that there may be increased costs associated with treating complications after Boston KPro I keratoprosthesis procedures.

General comments

One specialist commentator stated that people of African or Caribbean family origin may be at higher risk for corneal transplant failure and so they may benefit from the Boston KPro I.

One specialist explained that there is no set process for deciding whether to recommend keratoprosthesis with the Boston KPro I or a repeat PK. The clinical decision would be based on the likelihood of success for PK in each person, and the reason behind the poor prognosis. The commentator noted that if the patient's eye is in a poor prognostic group for PK, for example, having a repeat PK (second or more), vascularisation or stem cell failure, the treatment options would be to offer PK with immunosuppression, or the Boston KPro I. If the person is not well enough to have immunosuppression therapy, the Boston KPro I should be offered.