Topical Application of Perchlorate: A Toxicity Study in Rats

To investigate the ocular safety profile of topical perchlorate as a potential preventive treatment for nasolacrimal obstruction associated with excessive use of radioactive iodine therapy.

Nine Wistar male rats (18 eyes) were randomly assigned to receive an ocular application (topical eye drop on the OD, 3 times a day for 5 days) consisting of either: 1) sterile saline solution, 2) 30 mg/ml NaClO4 or 3) 30 mg/ml KClO4. The rat eyes were examined daily for corneal cloudiness/clarity, discharge, mucous secretions, conjunctival injection, eyelid erythema, and/or changes in behavior. Seven days after the first dose, the rats were euthanized and OU were harvested, fixed, embedded in paraffin, and stained with H&E and Masson's trichrome using standard techniques.

The data collected over the 7 days revealed no behavior changes or ocular complications in any of the 3 study groups. Pathologic analysis of the corneas revealed normal findings on all groups without signs of inflammation, fibrosis, or any other abnormality, and no difference between the treated and control eyes.

The findings of this study suggest that the use of topical perchlorate is safe to use on eyes in high concentrations. The efficacy of this compound in minimizing fibrosis of the nasolacrimal sac and duct warrants further study.