INTRODUCTION: Acute exposure to ultraviolet B radiation can cause photokeratitis. Retinol palmitate (RP) is known to have antioxidant properties and improve corneal healing. The aim of this study was to evaluate the effect of topical RP against phototoxic keratitis in rats.
METHODS: A total of 14 male Wistar Albino rats were exposed to 1 J/cm2 dose of 311 nm ultraviolet B radiation. The subjects were then divided into 4 study groups using the right and left eye: The RP-5 group (n=7) received topical 250 IU/g RP ointment and the Sham-5 group (n=7) received only the vehicle base component of the ointment 5 minutes after the exposure. The RP-120 group (n=7) received topical RP and the Sham-120 group (n=7) received the vehicle alone 120 minutes after the exposure. The eyes were enucleated 24 hours after the exposure and stained with hematoxylin and eosin for histopathological examination and a terminal deoxynucleotidyl transferase dUTP nick end labeling assay to test for apoptosis.
RESULTS: There was no statistically significant difference between the mean corneal epithelial thickness of the RP-5 group and the Sham-5 group (p=0.369). Furthermore, there was no significant difference between the RP-120 and the Sham-120 groups (p=0.765). The timing of the administration of RP resulted in no significant difference in the mean corneal epithelial thickness (p=0.608). Apoptotic cell count scores were not significantly different between corneas that received RP and those who received only the vehicle (p=0.530, p=0.107).
DISCUSSION AND CONCLUSION: Topical administration of a single dose of RP was not superior to the use of the vehicle base alone in a photokeratitis model produced using 1 J/cm2 of narrowband ultraviolet radiation in rats.