Thoraya Ammar MBBS, Presenter: Nothing to Disclose

B Paul, Abstract Co-Author: Nothing to Disclose

K Fong, Abstract Co-Author: Nothing to Disclose

J Herold, Abstract Co-Author: Nothing to Disclose

C Ferrett, Abstract Co-Author: Nothing to Disclose

R Tandon, Abstract Co-Author: Nothing to Disclose

C Liu, Abstract Co-Author: Nothing to Disclose

Ian Francis, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Osteo–odonto–keratoprosthesis (OOKP) surgery is a technique used to replace a damaged cornea in blind patients for whom cadaveric corneal transplantation is not a viable option. Analysis of the dimensions of the lamina using computed tomography (CT)/electron beam tomography (EBT) can localise early minor changes in the lamina and in so doing can predict cases where early re–intervention is necessary

A non-comparative case series was studied, based on the retrospective analysis of hospital records and cross-sectional imaging of patients who had undergone OOKP surgery between 1996-2004. Spiral/multi-slice CT with 3D reconstructions were performed. The dimensions of the lamina were then measured and compared to those taken at the time of surgery. An analogue scale scale (0-3) was used to grade the degree of resorption.

Twenty transplants for nineteen patients with a mean age of 50.9 years(range 19-79 years) were entered into the study. The average radiological follow up period was 27.5 months ( 0.9–91.7 months). Varying degrees of resorption of the laminae could be found in all of the transplants. Nine laminae showed only minor reduction in dimensions, grade 1. Five showed moderate reduction, grade 2 and six severe destruction, grade 3. The osteo-odonto-lamina was lost in 5 patients due to bone resorption. In 3 out of the 5 lost laminae CT was able to identify the laminae as high risk prior to clinical identification or spontaneous extrusion. This enabled a re-transplant in one patient and a transplant reversal procedure in the other two, and therefore avoiding complications such as aqueous humour leakage, inflammation, endophthalmitis, and extrusion of the optical cylinder. Explanted laminas clinically showed 100% concordance with the imaging findings.

The preservation of the osteo-odontal lamina is the key factor in the longevity of the OOKP. Post–operative CT and EBT are invaluable tools for detection of early, pre–clinical lamina resorption. This enables early prophylactic measures to be taken to preserve the lamina and prevent resorption related complications.

Ammar, T, Paul, B, Fong, K, Herold, J, Ferrett, C, Tandon, R, Liu, C, Francis, I, et al, , The Role of Imaging in the Evaluation of the Osteo–Odonto–Lamina in OOKP Surgery.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4410329.html