Abstract
Purpose Due to the shortage of human corneas for research purposes, our aim was to develop and optimize a bovine ex vivo model for the simulation of corneal storage and ophthalmic surgeries.
Methods Adult (>1 year) bovine eye bulbs were obtained from local slaughterhouses. Bovine corneas were excised within 4 hours from recovery and were preserved in hypothermic corneal storage (2-8°C, n=4) and corneal culture (31-35°C, n=4) conditions up to 14 days. The following corneal quality parameters were monitored at days 0 (before storage), 3, 7 and 14 of storage: endothelial cell (EC) density (ECD), EC mortality, EC morphology, corneal transparency and central corneal thickness (CCT) were evaluated with standard eye banks evaluation methods. EC and nuclear morphologies were also inspected after Alizarin Red + Trypan Blue stainings and light microscopy analysis. In addition, bovine eye bulbs underwent to cataract surgery simulation and to an open-bulb vitrectomy, followed by inner limiting membrane (ILM) removal, within 24 hours after recovery.
Results ECD and EC morphology parameters of calf corneas were comparable to human tissues, with bovine endothelium showing regular mosaic of hexagonal-shaped cells. Endothelial folds progressively appeared and became visible with a storage time-dependent manner. Folds overlapped with EC mortality areas. CCT was significantly higher in bovine corneas then in human corneas and, consequently, corneal transparency was significantly lower in bovine corneas then in human corneas. Alizarin Red+Trypan blue staining of calf endothelia revealed oval-shaped nuclei and binucleate cells were also detected.The bovine iris covers a significant portion of the anterior chamber area, resulting in a narrow rectangular pupil that limits the visualization of the posterior chamber. Therefore, the bovine anterior chamber was excised and removed, and a complete vitrectomy was performed in an open bovine eye bulb, followed by ILM peeling.Additionally, cataract surgery, from capsulorhexis to phacoemulsification could be performed in adult bovine eye bulbs.
Conclusions The presented bovine corneal and eye bulb model presented here represents a reliable alternative of human donor tissues and other ex vivo models in preliminary investigations related to the impact of various media, drugs, substances, and treatments during corneal preservation and ophthalmic surgical procedures.
