gms | German Medical Science

Purpose: The aim of the study was to establish a tomographic screening method for potential pathologies of corneal donors prior to keratoplasty in order to exclude them from further transplantation.

Settings: Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany.

Methods: Donor corneal tomography have been measured in a viewing chamber filled with preservation medium using a clinical OCT device. Custom made software was developed for extracting corneal surfaces from the raw data, which were analyzed in the central and peripheral regions. An adaptive non-linear edge enhancement algorithm was introduced for observing scars within the corneal volume. However, a thickness distribution map has been analyzed for detecting keratoconus diseases and corneas with extreme topographic irregularities. In order to assess the measurement reliability, five repeat measurements were performed.

Results: Eight donor corneas have been investigated: six intact grafts, which were not suitable for implantation because of the low endothelial cells density, and two keratoconus corneas, excised from patients during the corneal transplantation. A thickness abnormality was detected in one of the intact donor corneas, which was excluded from further analysis. The keratoconus corneas were obviously visible in OCT cross sectional images, and it was easily possible to identify by analysis of the thickness map. Overall, the measurements were reliable with Cronbach's alpha coefficient larger than 0.8.

Conclusion: Examination of donor corneas in viewing chambers was found to be suitable for an advanced screening routine prior keratoplasty. A proof of concept was demonstrated where irregular corneas as well as keratoconus corneas could be identified.