• The technology described in this briefing is the Boston Keratoprosthesis Type I (Boston KPro I). It is an artificial cornea used to provide a transparent optical pathway into the eye of people with corneal blindness, in whom corneal transplant may not be suitable.

  • The innovative aspects are that compared with other available keratoprostheses, the Boston KPro I is available off the shelf and does not need to be specially made for each patient so it can easily be resupplied after corneal graft failure. When needed, the device can also be customised. It is implanted in a 1‑step process. Other than the keratoprosthesis procedure, few treatment options are available for people for whom standard corneal transplant (penetrating keratoplasty) is not suitable.

  • The intended place in therapy would be after penetrating keratoplasty has failed, or if it is unlikely to succeed, such as in people with severe corneal opacity with wet blinking eyes. The Boston KPro I is assembled around a corneal graft before insertion into the person's eye.

  • The key points from the evidence summarised in this briefing are from 9 studies (n=1,202 eyes of 1,162 patients in total) published since NICE produced the interventional procedures guidance on implantation of a corneal graft–keratoprosthesis for severe corneal opacity in wet blinking eyes. Two of the studies were prospective and 7 were retrospective. They showed that Boston KPro I improved visual acuity and was more effective than penetrating keratoplasty in patients with severe corneal opacity who have already had a failed corneal graft.

  • Key uncertainties around the evidence are that the studies do not report which version of the Boston KPro I was used, and that most of the studies are retrospective. None of the studies were done in the UK, so the findings may not be generalisable to wider NHS populations.

  • The cost of the Boston KPro 1 is about £2,094 per unit (exclusive of VAT). This cost is approximate because the technology is not widely used in the NHS.