In July 2004, eye surgeons from the Singapore National Eye Centre together with a dental team from the National Dental Centre reported the first successful case of the Osteo-Odonto Keratoprosthesis (OOKP) ‘Tooth-in-eye’ surgery in Singapore, the first of its kind in the region.
Since the first successful case in a 19-year old boy from Thailand in June 2004, a total of 12 more OOKP surgery have been performed with phenomenal success. Ten of these patients have come from overseas, including Malaysia, Indonesia, Sri Lanka and Thailand, and 2 local patients. This surgery has now become a viable option for many blind patients who have lost their sight due to severe damage to their corneas and front part of the eye and eyelids. The list of local and regional patients awaiting the possibility of surgery continues to grow.
About OOKP Surgery
OOKP is a complex 2-stage operation which aims to restore vision to the most severe cases of corneal and ocular surface patients for whom all previous attempts to restore vision had failed. The procedure involves removing a canine tooth from the patient, shaping and drilling it to allow implantation of an artificial plastic corneal device (optical cylinder), and ultimately implanting it back into one eye a few months later.
A summary of the OOKP surgical procedure is as follows:
Stage 1 of the surgery involved 5 separate procedures:
1. Opening up one eye and removing the entire inner surface of his eyelids, his corneal surface, and all scar tissue from his previous eye injury
2. Removing the inner mucosal lining of the cheek and transplanting it onto the new surface of the eye
3. Removing a canine tooth and part of the adjacent bone and attached ligaments from his jaw (interestingly, the canine tooth is also known as the “eye-tooth”) (we recently have been able to modify the dental procedure to also use a premolar tooth in the even that the patient does not have suitable canine teeth)
4. Fashioning a bolt-shaped structure from this tooth-bone complex to receive a plastic optical cylinder which is cemented into place
5. Implanting the tooth-bone-cylinder complex into his cheek to grow a new blood supply
Stage 2 (about 4 months later)
This stage involves 2 separate procedures.
First, the cheek mucosal lining over the eye will be opened, and a circular opening made in his cornea to receive the implant. The inner contents of the eye will also be removed at the same time.
Secondly, the living tooth-bone-cylinder complex will be removed from the cheek, and placed within the eye, and the mucosal cheek lining will be replaced over the implant. At the end of the procedure, light can now enter through the plastic cylinder, and he will be able to see through this cylinder with good vision.
Results of the first 12 cases
Two-third of the cases have completed Stage 2 surgery (8 patients), while the remaining 4 will have their final Stage 2 surgery within the next 2-4 months. Of the 8 patients who have completed their surgery, amazingly, there have been virtually no complications and all 8 patients have vision restored to a level which previously had been deemed not possible. Of these 8, 3 have perfect vision of 6/6, 1 has 6/9 vision and 2 have 6/12 vision (all these 6 patients have vision good enough to drive) and the remaining 2 patients have 6/24 and 6/60 vision which are functional vision. Our longest follow-up in these patients is now over 15 months and all are doing very well.
A Team Effort
OOKP surgery has been an excellent example of multi-disciplinary collaboration involving a dedicated group of eye surgeons, dental surgeons, anaesthetists, radiologists, and visual therapists/psychologists contributing their respective skills and expertise in a complex procedure that eventually brings vision back to patients who will otherwise remain blind.
International Recognition for OOKP Program
The international medical community has recognized the efforts and contributions to the field. At the most recent international eye surgery scientific meeting (the American Society of Cataract and Refractive Surgery (ASCRS) Annual Meeting) which was held in Washington DC, the surgical team won the First Place Film Award under the “New Techniques” Category, for the OOKP procedure, which has never been performed in the US. This is the first time Singapore surgeons have won the first place award at this prestigious meeting which is one of the largest clinical ophthalmology meetings in the world.
There has also been groups of professionals from other parts of Asia who have expressed interest to observe the surgery and learn the OOKP techniques. They will also be sending their most severe cases to Singapore for OOKP surgery. Several countries in the Middle East have also expressed keen interest to send patients and learn OOKP surgery.
Patients selected for surgery will include those cases of complete blindness in which conventional corneal transplants will not work. We currently have many more patients in the region who intend to come to Singapore for sight restoration with OOKP surgery.
Through collaboration with SingaporeMedicine in a number of roadshows and media publicity in the region, many foreign patients now have come to know of the new OOKP surgery and its excellent results and have made arrangements to Singapore for sight restoration with OOKP surgery.
The Surgical Team
1 OOKP Surgeons:
Assoc Prof Donald Tan
Deputy Director, Singapore National Eye Centre (SNEC)
Head and Senior Consultant, Corneal & External Eye Disease Service, SNEC
Director, Singapore Eye Research Institute
Head, Dept of Ophthalmology, National University of Singapore
Dr Andrew Tay
Consultant, Dept of Oral and Maxillofacial Surgery,
National Dental Centre (NDC)
Dr Julian Theng
Consultant, Corneal & External Eye Disease Service, SNEC
Dr Lye Kok Weng
Registrar, Dept of Oral and Maxillofacial Surgery, NDC
Dr Raymond Wong
Registrar, Dept of Oral and Maxillofacial Surgery, NDC
2 OOKP Anaesthetist
Dr V Sivagnanaratnam
Visiting Consultant Anaesthetist, SNEC
Emeritus Consultant Anaesthetist, Changi General Hospital
3 SNEC Corneal Fellows, Corneal Nurses and OT Nurses
4. NDC LAOT Team
5. OOKP Surgical Advisor: Dr Christopher Liu