An experimental study was performed in an effort to learn more about the possible mechanisms involved in the production of toxic ocular manifestations. Three normal subjects were digitalized and maintained on average, therapeutic, nontoxic doses of digitalis for durations of two to four weeks. Several parameters of visual function were studied, but the only significant findings in this experiment concerned the elevation of dark adaptation thresholds noted in two of the three subjects. These elevated thresholds gradually returned to normal after the use of digitalis was discontinued.
This study indicates that digitalis can disturb the normal function of the receptor cells and interfere with the normal function of the visual cortex, the ciliary body, and the cornea.
ROBERTSON DM, HOLLENHORST RW, CALLAHAN JA. Receptor Function in Digitalis Therapy. Arch Ophthalmol. 1966;76(6):852–857. doi:10.1001/archopht.1966.03850010854013