Comparative morphological evaluation of animal corneal parameters

The purpose of this study was to broaden the basic knowledge of corneal morphological structures in pigs, cows and rabbits and to find morphological and histological differences in the constituent corneal structures. After slaughter, corneal samples of 24 animals, including cows, pigs and rabbits, were investigated. Forty-eight eyeballs (n = 48) of 8 pigs, 8 cows and 8 rabbits were used for this study. Central corneal thickness (CCT) values in cows were higher than those in pigs (P < 0.001) and rabbits. In rabbits, CCT, as a percentage of the eye axis length, was 55.03% greater than in cows and 40.55% greater than in pigs (P < 0.001). The thickness of substantia propria (stroma) depended on the species and accounted for more than 80% of the thickness of all layers of the cornea. The thickness of the anterior epithelium amounted to 15.81% of the thickness of all layers of the cornea in cows, 11.79% in pigs, and 8.48% in rabbits (P < 0.001). The data analysis showed that the caudal limiting membrane + endothelium was the thinnest layer of the cornea, with thickness ranging from 0.88% to 2.40% of the total thickness of all layers of the cornea in the three species under study (P < 0.001). A statistically significant negative correlation was determined between the anterior epithelium and substantia propria in corneas of cows, pigs and rabbits (P < 0.001). This paper describes the morphometric parameters of the cornea in pigs, cows and rabbits. These parameters will be of use to scientists using animal models in vision science research.