Influence on corneal permeability of bathing with solutions of differing reaction and tonicity

Abstract

(1) The permeability of the limiting cellular layers of the rabbit cornea to 24Na has been investigated by bringing a solution of it in contact with the eye for 10 min., and analysing the amount that penetrates into the cornea and aqueous humour. Test solutions of NaCI concentrations from 0 18 to 10 per cent. and ofpH from 2 to 11 were used. (2) Solutions hypotonic to 0-9 per cent. NaCl cause a rise in epithelial permeability which reaches a maximum of about ten times normal at about 0 4 per cent. NaCl. Hypertonic solutions do not alter, or tend to decrease, the epithelial permeability. (3) Increasing the tonicity of the solution bathing the cornea in the neighbourhood of 0 9 per cent. NaCl causes a rise in the permeability of the endothelium. (4) The permeability of the epithelium to 24Na is the same with a 0 9 per cent. NaCl solution as with an isotonic glucose solution. (5) Solutions buffered from pH 4-10 do not affect the epithelium but outside this range increase its permeability. (6) The bearing of these results on the nature of the cellular layers, and their application to the preparation of drugs for instillation in che eye is discussed.