PURPOSE: To evaluate ocular toxicity of povidone-iodine eye drops at a concentration of 2.5% and 0.5% and to investigate the effects on corneal epithelial wound healing and histopathological alterations. METHODS: Each group (PVP-I 2.5% and 0.5%) consisted of 20 rabbits. A central circular corneal epithelial defect of 6.5 mm diameter was created and the povidone-iodine eyedrops (2.5% and 0.5) instilled in the right eye and distilled water in the left eye (control) of each rabbit, every hour, during 3 days. Biomicroscopical examinations were performed every day, focussing on the corneoconjunctival surface and the diameter of the lesion, using fluoresceine eye drops, photodocumentation, and a computerized image analyzer. After the third day the rabbits were sacrified and the excised corneas histopathologically evaluated. Statistical evaluation was performed using Friedman, Mann-Witney, Wilcoxon, Fisher and Chi-squared tests. RESULTS: Povidone-iodine eye drops, at a concentration of 2.5%, caused an increase in the wound healing time (p= 0.087) and conjuntivitis in 100% of the eyes with mucous secretion in 80%, punctate ceratitis in 40%, and discrete stromal edema in 10% of the cases. The histopathological examination showed corneal ulcers and vacuolic degeneration of the endothelial layer in 100%, as well as an inflammatory infiltrate with eosinophils in 80% of the cases. The eyes treated with povidone-iodine eye drops at a concentration of 0.5% and the control eyes showed complete epithelial wound healing after 72 hours, and histopathologically normal epithelization. Only in one case, a discrete perilimbar leucocytic infiltrate was observed. CONCLUSION: The ocular toxicity of povidone-iodine eye drops is concentration-dependent. The use of the eye drop at a concentration of 2.5% is not adequate for daily and repetitive use. In contrast, at a concentration of 0.5% no toxicity was observed.
Povidone-iodine; Ophthalmic solutions; Epithelium corneal; Conjunctiva; Animal experimentation; Rabbits
