Using microdensitometry, the depletion course of glycogen from the corneal epithelium was measured for periods of oxygen deprivation of up to five hours. Within 30 minutes, glycogen depletion was found to be proceeding at its maximum rate, coming to a minimum stable level, equivalent to diastase depletion, by four hours. Concurrent swelling of the epithelium proceeded more regularly, ie, with less initial acceleration, stabilizing at four hours also.
Uniacke CA, Hill RM. The Depletion Course of Epithelial Glycogen With Corneal Anoxia. Arch Ophthalmol. 1972;87(1):56-59. doi:10.1001/archopht.1972.01000020058012