IN CONNECTION with recent studies of the permeability and other properties of the excised cornea,1 measurements of electrical impedance might be expected to give additional pertinent information. It is now generally accepted that the impedance of biologic tissues is directly related to their ionic permeability.2 In the same way that measurements of impedance of solutions of pure electrolytes may be considered to measure (aside from concentration effects) the ability of the ions to diffuse through the medium, measurements of impedance of the cornea may be considered to give a measure of the ability of the ions to move through the tissue.
The impedance consists of a resistive component, related to movement of ions in an electrolyte (and thus generally accepted to be a measure of permeability to ions), and a capacitative component, probably associated with dielectric properties and polarization of the tissue. The resistive component is of principal
HOLT M, COGAN DG. THE CORNEA: VIII. Permeability of the Excised Cornea to Ions, as Determined by Measurements of Impedance. Arch Ophthalmol. 1946;35(3):292–298. doi:10.1001/archopht.1946.00890200298008
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