022 Développement d’un dispositif de quantification de la transparence, du plissement et du gérontoxon pour les cornées conservées en organoculture

Abstract

To develop an image analysis device devoted to the measurement of donor corneal transparency (T), folding (F) and clear corneal diameter excluding gerontoxon (corneal arcus) (G) during organ culture. High resolution digital images (2592×1944 pixels) of a retroilluminated test chart comprising parallel horizontal lines viewed through the cornea placed in a petri dish were captured and analysed using a dedicated software. T (%) was a ratio of local contrast of the test chart and F (%) was a ratio of mean of line profiles of the test chart, each measured with and without the cornea. Area of clear cornea outside gerontoxon was calculated from a circle delineated by the observer using a specific software tool. On each image, three independent experts classified T, F and G according to 3-level score (++/+/0) which served as reference. Human corneas (fresh, organ cultured before and after deswelling) (n=179) were consecutively analysed to include a broad spectrum of T and F. The device was able to discriminate between the three classes of T, F and G, established by the experts. T was 20±4, 36±8 and 51±10% respectively for transparency deemed poor, average and excellent (P< 0.01). F was 29±10, 22±6, and 17±6% respectively for folding deemed high, average and minimal (P<0.01). Diameter of clear central cornea was 7.7±1.1, 8.9±0.8, 10.4±0.6 mm respectively for gerontoxon deemed severe, moderate and absent (P<0.01). This simple and original device provides reliable quantitative objective measures of corneal transparency, folding and corneal arcus. It will help standardizing quality assessment of corneas among eye banks. A trial designed to assess the ability of the device to select corneas before delivery in the setting of the routine practice of our cornea bank is ongoing (PHRC, appel d’offre local du CHU 2007).