Fluorometric measurement of light absorption by the rabbit cornea

A bench specular microscope, modified to perform as a scanning microfluorometer, was used to make simple and precise measurements of the absorption of visible light by the isolated rabbit cornea. The tissue was scanned while identical FITC dextran solutions were perfused over both the surfaces, and the measured fluorescence levels in the solutions on the two sides were compared. The alteration in level corresponds to the difference between the absorption of the cornea and that of of an equal thickness of the solution, which was determined in a separate experiment. The absorption of light at 500 nm ranged from 0-8% with a mean of 3.3% (n = 20; S.E. = 0.52). Pigmented and non-pigmented rabbits did not show any clear difference in absorption. These results suggests that light absorption is not a major source of error in anterior segment fluorophotometry.