Corticosteroids and the active ion transport of the isolated human lens

Glucocorticoids may induce posterior subcapsular cataract in man following topical or systemic administration. Translenticular potential difference (PD) and short circuit current (SCC) measurements were performed on the isolated human lens. 6-methylprednisolone 10(-4)mol 1(-1) did not change PD and SCC. However, 10(-3) and 10(-2)mol 1(-1) prednisolone reduced PD and SCC already 45 min after administration. An inhibition of SCC from 5.4 microA cm-2 to 3.8 microA cm-2 was obtained after prednisolone. PD was reduced from 6.2 mV (anterior side positive) to 4.6 mV, while resistance was unchanged. The effect on PD and SCC could only be demonstrated when prednisolone was given to the epithelial (anterior) side of the lens. After the 2-3 hr incubation of human lenses in 10(-2)mol 1(-1) prednisolone macroscopically visible opacities under the posterior lens capsule could be seen regularly. Aldosterone had no effect on PD, SCC and transparency. The data are consistent with the hypothesis that in the human lens glucocorticoids may induce cataract formation by inhibition of epithelial electrolyte transport.