Understanding Artificial Cornea Or Keratoprosthesis- Dr QB Maskati

Kisan Jadhav (name changed) was studying for his master’s degree in history in Jalna, a small town in central Maharashtra. He was a studious, quiet youngster, intent on realizing his dream of becoming a professor after completing his Ph.D. His life changed one day, when some miscreants, mistaking him for someone else, threw acid upon his face. He was admitted to the local hospital with extensive chemical burns of the face and both eyes severely damaged.

Several months of painful reconstructive surgeries later his face regained some semblance of normalcy. Unfortunately, he was totally blind in both eyes. The left eye had shrunk to a third of its size and was unable to even perceive light. The right eye could perceive light, but the cornea was totally opaque and the eye was bone dry with virtually no tear production. In such a situation with inadequate tear secretion, a corneal graft is doomed to failure. Fortunately, his eye surgeons had heard of a new treatment suitable for such patients. He was referred to Mumbai and operated upon in 2 stages and an artificial cornea or Pintucci keratoprosthesis was implanted in his right eye. It is now 11 years since this surgery. Kisan has 6/6 or normal distance vision with glasses and can read the tiniest of print without any glasses. He has resumed his studies and has passed his MA exam.

These are some of the frequently asked questions about keratoprosthesis or Kpro (KP)

Q. Who are suitable candidates for KP?
A. Those blind in both eyes, with the at least accurate perception of light in the better eye. The surgery is done in only one eye.

Q. Can those who have had corneal grafting surgery multiple times, which have failed to be operated for KP?
A. Yes, those who have had repeatedly failed or rejected corneal grafts with vascularisation are excellent candidates for 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

Q. 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 a corneal transplant is not advised?
A. Such patients can be operated upon by either Pintucci or Modified Osteo-odonto KP (MOOKP) surgery.

Q. Is this surgery for Pintucci or MOOKP expensive?
A. Yes, the cost of the 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 of surgery lasts for 2-3 hours. Some tissue also needs to take from the patient’s mouth. It is generally done under general anaesthesia. It is, however, cheaper than a cochlear implant or cardiac surgery.

Q. Can this surgery be done instead of a corneal graft?
A. 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 the first choice for those with opaque corneas without vascularisation and with adequate tears.

Q. Can the KP be rejected?
A. No. It is made of the same material that most IOLs are made – polymethylmethacrylate or PMMA, which is an inert plastic.

Q. What is the success rate?
A. The author has done approximately 85 cases of Pintucci Kpro so far, since 1997. In the author’s hands, the 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 1500 cases over 20 years with a similar success rate. The MOOKP has had over a 100 done at a single center in Chennai since the past 15 years and has enjoyed an even better success rate

Q. What about other KP devices?
A. 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 MOOKP or Osteo-Odonto KP also called the “eye-in tooth” KP. This requires the 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. Over a 100 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 and several Asian countries including India. 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.

Q. Is there a difference in patient selection between the Pintucci or MOOKP and the Boston KP?
A. 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 the 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 or MOOKP works best.