OSTEO-ODONTO KERATOPROSTHESIS (OOKP) OR 'TOOTH-IN-EYE' SURGERY

Osteo-odonto Keratoprosthesis (OOKP) is a unique form of artificial cornea surgery for patients with the most severe, end-stage forms of corneal blindness, that are not amenable to corneal transplantation or other forms of surgery.  We were among the first in the region to perform this complex, two-stage "Tooth-in-Eye" surgery (OOKP) which was initiated in 2004. To date we have performed surgery in 36 patients from around the Asia-Pacific region and helped to restore sight in these patients.

Who is suitable for OOKP surgery?

Patients who have severe scarring or damage involving the front of the eye (the cornea, sclera and conjunctiva) that is not suitable for other forms of corneal transplant and/or ocular surface reconstruction procedure may benefit from this form of surgery. A healthy nerve and retina are required to achieve good vision following this complex procedure.
 
Some indications for surgery include patients with severe allergic reaction to medications (Stevens-Johnson Syndrome) and severe chemical burns (acid, alkali), thermal injuries, or cases of multiple previous failed corneal grafts.

What does the surgical procedure involve?

Also known as "tooth-in-eye" surgery, OOKP involves a two-stage surgical procedure that is usually performed about six to eight (6 - 8) weeks apart.
 
Stage 1: This step involves the removal of a canine tooth (with its root and part of the adjacent bone) from the patient. The tooth is then fashioned into a cube with a hole drilled into its centre. An artificial plastic corneal device called an optical cylinder is implanted into the hole. The optical cylinder will channel light to the retina.

This tooth structure is inserted into the patient’s cheek to grow new blood vessels. At the same time, scar tissue from the surface of the eye is carefully excised and removed and tissue from the inner mucosal lining of the cheek is harvested and transplanted onto the surface of the eye.
 
Stage 2: In the second stage of the procedure, the patient’s damaged eye which was previously covered with cheek lining is opened. A circular opening in the cornea is made, and the iris and lens are removed.
The tooth structure is then removed from the patient’s cheek, implanted within the eye and covered with the cheek lining. 

At the end of the procedure, light can pass through the plastic cylinder to allow clear vision. 

What are the outcomes and results worldwide?

Good long-term outcomes have been reported with this procedure in literature.

A long-term study of 181 patients puts the chances of retaining an intact OOKP after 18 years at 85%.  (Falcinelli G, Falsini B, Taloni M et al. Modified osteo-odonto-keratoprosthesis for treatment of corneal blindness: long-term anatomical and functional outcomes in 181 cases. Arch Ophthalmol 2005; 123 (10): 1319–29.)

What are our results with the procedure?

At SNEC we initiated the OOKP program in 2004 and to date have performed 36 cases and helped to restore sight in these patients (Tan et al. Keratoprosthesis surgery for end-stage corneal blindness in Asian eyes. Ophthalmol 2008;115:503-10). Our results have been excellent – we did not encountered any instability problems or extrusion related to the implant.

1. Visual acuity

All patients had significant improvement in vision compared with their preoperative status (mean postoperative BCVA: 0.61, p = 0.000). Over ¾ of patients attained at least 6/12 vision, while more than half attained perfect 6/6 vision. All the other patients achieved their best potential vision, but were limited by other preexisting eye conditions such as previous retinal or optic nerve damage.
 
2. Long-term retention of the OOKP complex and survival:

We have not had any case of implant extrusion to date with the OOKP procedure.  

                       The Sunday Times, 24 August 2004 
 
Please visit the following relevant links:

Outcome Results on Corneal & External Eye Disease Procedures
Corneal & External Eye Disease Clinical Staff
I Want an Eye Examination / an Appointment
Care After Corneal Transplant
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