Evaluation of donor tissue with a new videokeratoscope - The Keratron Scout

Purpose. To evaluate the percentage of corneas with an epithelial surface quality sufficient for a reliable screening of donor eyes with keratoconus and after photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) treatment for refractive errors. The usefulness of the computer-assisted, video-keratography system Keratron Scout in making this determination was evaluated. Methods. Forty eyes from 20 donors were screened within 30 minutes after enucleation and within 24 hours postmortem. At first a meticulous slit-lamp evaluation of the corneal surface and stroma was performed; thereafter eight pictures per eye were taken with the Keratron Scout, and an ultrasound pachymetry reading of the corneal center was taken. "True curvature," algorithm-based color maps were used for analysis. Epithelium was not removed, because all corneas were suitable for transplantation. Balanced salt solution was used to keep the corneas moist. The low intraocular pressure regularly found in postmortem eyes was raised to within normal ranges by intravitreal injection. Corneas were classified according to the integrity of their epithelial surface, which influences the regularity of the topography maps. Results. The quality of the images acquired varied, depending mostly on the quality of the epithelium. Regular topography patterns were found in 15 eyes (37.5%); in 14 eyes (35%), minimal epithelial roughness or sloughing in just one quadrant of the cornea was detected. Moderate to severe epithelial irregularities or defects were found in nine eyes (22.5%). Screening for abnormal shape was possible in 90% of the tested eyes, where no changes caused by prior refractive surgery or keratoconus were apparent. Conclusion. The postmortem quality of the epithelial surface allows screening for keratoconus or refractive procedures in the majority of donor eyes. Video-keratography with the Keratron Scout seems to offer a sensitive and quick method for this purpose, thereby adding an additional safety feature to eye banking in view of the rapid development of corneal refractive surgery.