THE ENZYME systems involved in the respiration of the lens have not been established. Whereas many attempts have been made to demonstrate that the same enzymes—flavoprotein and cytochrome-cytochrome oxidase1—which catalyze oxygen uptake in other tissues also function in this capacity in the lens, the only direct evidence, to our knowledge, for the existence of a flavoprotein or a cytochrome-cytochrome oxidase system in the lens is that obtained by Philpot and Pirie.2 These authors reported two analytical values for the riboflavin content of the lens. Using the microbiologic method of assay, they found that lenses devoid of capsule, and presumably therefore of epithelium, contained in the two instances 0.05 and 0.12 γ of riboflavin per gram of wet weight. Other investigators3 failed to detect riboflavin or flavoprotein in the lens by fluoroscopic methods.
Von Euler and Günther3b and Burdon-Cooper and Lewis4 were unable to demonstrate
KINSEY VE, FROHMAN CE. STUDIES ON THE CRYSTALLINE LENSIV. Distribution of Cytochrome, Total Riboflavin, Lactate, and Pyruvate and Their Metabolic Significance. AMA Arch Ophthalmol. 1951;46(5):536–541. doi:10.1001/archopht.1951.01700020549011