The penetration of topical cysteamine into the human eye.

The penetration of cysteamine into human aqueous was measured to assess its suitability as a topical agent for the prevention of radiation-induced cataract. Cysteamine drops (0.5% and 1.0%) were administered preoperatively to cataract patients every half hour, for two, four, six or eight hours. Aqueous humor was collected at the start of surgery and assayed for total free thiol. There was no significant difference in the aqueous thiol level of any of the treatment groups compared with the controls. No side effects were observed.