THE NONUNIFORM DISTRIBUTION OF ALBUMIN IN HUMAN AND BOVINE CORNEA

In our previous studies, we noted a non-uniform distribution of protei n tracer preferentially entering the anterior stromal lamellae of the cornea from the limbus. Given other differences reported previously be tween the anterior and posterior lamellae of the cornea, and the numbe r of corneal disorders in which abnormalities are preferentially confi ned to either the anterior or posterior lamellae, we were prompted to examine the distribution of albumin in normal human and bovine cornea. The distribution of albumin in bovine and human cornea was; studied i mmunohistochemically. Total soluble protein and albumin in the anterio r 1/3 and posterior 2/3 of the central, middle and peripheral cornea o f bovine eyes was measured biochemically. To aid in interpreting the f indings, a theoretical model was developed based upon the combined eff ects of diffusive and convective transport. Using immunohistochemical methods, in both bovine and human eyes, intense staining of albumin wa s found in the anterior 1/3 of the corneal stroma. There was a gradual reduction in staining intensity from the limbus to the central cornea in the anterior corneal stroma. Less staining was found in the poster ior 2/3 of corneal stroma. Additionally, a greater concentration of so luble protein and albumin was found in the anterior stroma than in the posterior stroma of the bovine eyes by biochemical analyses. The theo retical model demonstrated that this distribution of protein required a difference in excluded volume fraction between the anterior and post erior stroma and was consistent with a convective nux originating at t he limbus and passing through the corneal stroma. The soluble proteins of the bovine and human cornea are preferentially concentrated in the anterior cornea and near the limbus. This distribution is likely due to differences in excluded volume fraction between the anterior and po sterior stroma and a small convective nux passing through the cornea. (C) 1997 Academic Press Limited.