In Vitro Corneal Tomography of Donor Cornea Using Anterior Segment OCT.

PURPOSE

The aim of this study was to establish a tomographic screening method for revealing potential pathologies in corneal donors before keratoplasty so they may be excluded as candidates for corneal transplantation.

METHODS

Donor corneal tomographies were measured in a viewing chamber filled with preservation medium and with the use of a clinical optical coherence tomography (OCT) device. Custom-written software was developed to extract corneal surfaces from the raw data, which were analyzed in the central and peripheral regions. An adaptive nonlinear edge-enhancement algorithm was used to observe scars within the corneal volume. The thickness distribution map was analyzed to detect keratoconus and corneas with extreme topographic irregularities. Measurements were repeated 5 times to assess reproducibility.

RESULTS

Eight corneas were investigated: 6 randomly selected intact donors, unsuitable for implantation because of low endothelial cell densities, and 2 keratoconus corneas, excised from patients during corneal transplantation. A major thickness abnormality was detected in one of the intact donor corneas, so it was excluded from further analysis. The keratoconus corneas were clearly evident in optical coherence tomography cross-sectional images, and similarly, they could easily be identified by analyzing the thickness map. Overall, the measurements were reliable and had a Cronbach's alpha coefficient greater than 0.8.

CONCLUSIONS

Donor corneal examination using sterile viewing chambers was found to be suitable as a pre-keratoplasty advanced screening routine. A proof of concept was demonstrated, which could identify both irregular corneas and those affected by keratoconus.