A news article by The Times Health Editor, Sam Lister, talks about pioneering surgery at Centre for Sight.
Sam Lister Health Editor
Thursday December 23rd 2010
Thousands of people left blind or with minimal vision because of damage to their corneas could have their sight dramatically improved thanks to advances in the use of prosthetic implants, a leading doctor says.
Sheraz Daya, consultant ophthalmologist at Queen Victoria Hospital in East Grinstead, West Sussex, said that people who lost their sight because of corneal injury or disease should be considered for artificial implants if corneal transplant and stem cell treatments had failed. Such had been the clinical progress in synthetic corneas that they should become a routine recourse for saving sight, particularly in elderly patients, Mr Daya said.
The cornea is the transparent front part of the eye that covers the iris, the pupil and the chamber behind. The lens and the cornea refract light and are responsible for much of the eye's focusing power. Of the 1200 Keratoprosthesis operation carried out last year, more than two thirds were in the United States. Only a handful are carried out in Britain each year.
The operation involves placing a lens attached to a plate through a donor cornea. This is then locked on to a back plate, with a corneal graft sandwiched in between. This donor cornea is then used to stitch the lens onto the patient's eye. Even if the foreign tissue in the graft causes rejection, this should only cause clouding on the fringes of the cornea, and not in the synthetic centre of the implant through which the patient will see.
The operation should now become more commonplace, Mr Daya said, thanks to three recent advances:
1) The development of a glaucoma tube-valve places within the eye at the time the prosthesis is applied to reduce pressure, along with better monitoring of the optic nerve;
2) More effective antibiotic treatment that avoids the risk of endophthalmitis, an infection caused by bacteria entering the inner eye;
3) Use of sillicon hydrogel contact lens that acts as a protective seal to prevent the epithelium, the outer protective layer of the cornea which holds moisture, from breaking and contributing to corneal melts and infections.
The speed with which the prosthesis could be effective, and the lack of a need for long-term use of immuno-suppreasent drugs to allow a patient's body to accept the donor cornea, meant it could be a particular use to the elderly, Mr Daya said. "If the patient is in their eighties and is going to struggle to tolerate immune suppression, we can give them a real quality of life with keratoprosthesis now. Why put them through immuno-suppresants for three or four years which might actually be the duration of their lifespan?"
Mr Daya, who is also Medical Director of the Centre for Sight at East Grinstead, a private clinic, said that although Keratoprosthesis was expensive, costing £3000 for the implants and more than £200 a week for antibiotics, it should not be beyond the NHS.
Research published this year in the US found the procedure to be a highly cost-effective intervention, at about £10,000 per quality-adjusted life year (QALY), a measurement used to assess the value of the clinical procedures. In Britain, £30,000 per QALY is the level above which the National Institute for Health and Clinical Excellence would normally rule treatment too expensive.