Who are suitable candidates for KP?
Those blind in both eyes, with at least accurate perception of light in the better eye. The surgery is done in only one eye.
Can those who have had corneal grafting surgery multiple times, which have failed be operated for P-KP?
Yes, those who have had repeatedly failed or rejected corneal grafts with vascularisation are excellent candidates for P-KP, provided sonography shows the retina is intact and there is no severe glaucoma. If their eyelids blink normally and they have adequate tear secretion, another simpler Keratoprosthesis called the Boston Keratoprosthesis or Boston KP is preferred as it is a single stage operation
What about those with corneal opacity who have been refused corneal transplant because of dry eye or very vascularised cornea or diseases like pemphigus or Stevens Johnson syndrome or chemical burns where corneal transplant is not advised?
Such patients can be operated upon forP- KP surgery.
Is this surgery expensive?
Yes, the cost of the Pintucci Keratoprosthesis, which is imported from Europe, is a little high. Besides, the surgery is technically demanding. It is done in 2 stages, 2 months apart. Each stage ofsurgery lasts for 2-3 hours. Some tissue also needs to taken from the patient’s mouth. It is generally done under general anaesthesia. It is however cheaper than a cochlear implant or cardiac surgery.
Can this surgery be done instead of a corneal graft?
No. This is a surgery of last resort. It is done only for those who have failed grafts with dry eye or in whom grafting is not advisable. Corneal grafting is still the treatment of first choice for those with opaque corneas without vascularisation and with adequate tears.
Can the KP be rejected?
No. It is made of the same material that most IOLs are made – polymethylmethacylate or PMMA, which is an inert plastic.
What is the success rate?
The author has done approximately 85 cases so far, since 1997. In the author’s hands, t he success rate, i.e. those patients retaining useful vision after the surgery is 65% The late Dr. Stefano Pintucci, the inventor of this device, had done over a 1500 cases over 20 years with a similar success rate.
What about other KP devices?
There are several other designs available in the market. The 3 commonest besides the Pintucci are
a) the Daljit Singh champagne cork KP (done by the Singh group based in Amritsar, India, which uses stainless steel sutures to secure the KP in the eye – this group has the largest series reported in the world)
b) the OOKP or Osteo-Odonto KP also called the “eye-in tooth” KP. This requires use of a healthy canine tooth from the patient. It can only be done in adults and requires a team approach, including a dentist. It is also more expensive, requiring serial MRIs to check the health of the implanted tooth and cannot be done in children. A few have been implanted mainly in Chennai, India. Besides Rome, Italy, it is also done in Birmingham, UK and in Singapore in significant numbers.
c) The Boston KP or the Dohlmann KP. This is an American design and enjoys good popularity in the US and Latin America. It requires a donor cornea as well. It is a simpler technique and is done in one stage. The cosmetic appearance is also better. The author has started doing this procedure in Mumbai from February 2009, in select cases. He has also demonstrated this surgery to an audience of 200 ophthalmologists in Bangalore, restoring sight to a man blind in both eyes since over a dozen years, prior to the surgery.
You do tend to brag, any opportunity you get. Is there a difference in patient selection between the Pintucci and the Boston KP?
I will ignore the first sentence. Yes there is a difference in patient selection criteria. The Boston KP needs the patient to have some amount of tear production. The patient should also not have any history of corneal melt, nor should he suffer from systemic diseases that could result in corneal melt. Therefore it is done in damaged or diseased corneas where the severity of the disease is less. For very severe dry eyes, with melted corneas such as Stevens’ Johnson Syndrome or chemical injuries, the Pintucci KP works best.