Investigation of Capsaicin-induced Superficial Punctate Keratopathy Model Due to Reduced Tear Secretion in Rats

ABSTRACTPurpose: The present study investigated the usefulness of the superficial punctate keratopathy (SPK) model due to reduced tear secretion induced by the injection of capsaicin in neonatal rats.Methods: On postnatal day 4, rats were injected subcutaneously with a single dose of capsaicin. Ocular surface symptoms were evaluated by measuring corneal sensitivity, tear secretion and corneal fluorescein score. Furthermore, the effect of pilocarpine was investigated by measuring tear secretion and corneal fluorescein score in this model. The influence of discontinuation of pilocarpine application was also examined.Results: Capsaicin caused a dose-dependent reduction of tear secretion and increase of corneal fluorescein score. In addition, 50 mg/kg capsaicin-treated rats showed a sustained decrease of corneal sensitivity and tear secretion, and an increase of corneal fluorescein score compared with vehicle-treated rats. Moreover, capsaicin-treated rats showed SPK. Instillation of pilocarpine significantly ...