Morphological analysis of corneal findings modifications after death: A preliminary OCT study on an animal model

The aim of this work was to describe, for the first time, the morphological modifications, in a three-dimensional mode, of the central cornea at different intervals since death. The study design involved the analysis of 30 eyes (15 heads) of female, adult sheep (>2 years) sacrificed at a local slaughterhouse. The eyes, after animal decapitation, were examined in situ, without enucleation. Ocular globes were stored at well-known temperature (within a range of 12-22 °C) and humidity (within a range of 50-60%). The instrumental analysis was executed using a portable spectral-domain OCT (SD-OCT) system (iVue SD-OCT, Optovue Inc, Fremont, CA) calibrated to the corneal mode. OCT imaging was performed at different time-points since death. Pachymetric map, morphological and ultrastructural analysis (epithelium, stroma, and endothelium), were performed for each time-point. After an initial thinning of tissues and an enhancement of epithelial reflectivity, stromal thickness increased from the 2nd up to the 6th hour. Subsequently, a new trend incorneal thinning was observed in association with the appearance ofone or more demarcation lines between the anterior andposterior stroma. After the 12th hour, a recurrence of corneal swelling was detected in association with thedelamination of stromal tissue. Since the 24th hour, the epithelium disappeared in 50% of cases and the anterior chamberdepth progressively decreased. At the 48th hour, various ocular structures showed the onset of putrefaction processes, such as theappearance of hyper-reflective dots in anterior chamber, iridocorneal contact, and the massive vacuolization of theposterior stroma until the total delamination. The portable OCT system is a useful approach for in situ postmortem corneal examination, and it may be potentially applied for the selection of donor cornea in transplantology and for the determination of post-mortem intervals in forensic medicine.