Response of the cornea to far ultraviolet light: an ultrastructural study

Quantitative changes were measured and ultrastructural alterations were detected in rabbit corneas after exposure to a far ultraviolet irradiation (UV). Low dose exposure (105 - 8 x 105 erg/cm2) resulted one day later in a thicker epithelium and loss of the intercellular permeability barrier. In corneas exposed to higher doses (5 x 106 erg/cm2), the epithelium was considerably thinner one day later, whereas 4 days later it was of normal thickness and the endothelial cells became degenerated. The highest UV dose exposure used (a total of 20 x 106 erg/cm2 given in 4 equal daily doses) resulted in (1) swelling of the stroma and disorganization of the collagen fibers; (2) disappearance of the basement membrane; (3) degeneration of the endothelial cells; and (4) considerable reduction of epithelium thickness.