The Effect of Topical Honey on the Healing of Cornea Following Alkaline Injury and Surgical Abrasions in Rats

Abstract

Corneal traumatic injury and chemical burn are common types of corneal injury that may lead to persistent ulceration, corneal opacification and angiogenesis. This study aims to assess the therapeutic effects and the underlying mechanisms of topical honey in the healing of cornea after alkaline-induced and surgically induced corneal injury. Sixty albino rats were divided into three equal groups were included: GI: normal control group, GII: alkaline-induced injury group using a 3 mm chemical filter paper soaked in 1 N Na OH, and GIII: surgically induced injury group using PRK spatula to remove corneal surface epithelial layer. Left eyes of rats in GII and GIII groups received honey treatment after injury while right eyes had injury only. Honey was applied five times/day to the left corneas of rats in groups GII and GIII. Assessment of inflammatory changes and healing of corneas were done before scarification using inflammatory index score and fluorescein staining score, respectively. Rats were sacrificed at 24 hours, 48 hours and 7 days after injury. After sacrificing, half number of corneas was used for histopathological assessment and the other half was used for ELISA assessment of VEGF, TGF-β and TNF-α levels in corneal tissue homogenates. There was significant improvement of fluorescein staining score and ulcer healing in both models in honey-treated compared to untreated corneas. Furthermore, in alkaline-induced injury model, inflammatory index score was significantly decreased in honeytreated corneas compared to untreated ones. Regarding histopathology, there was a significant decrease in histological inflammation grade in honey-treated corneas compared to non-treated ones in the alkaline-induced injury model. Finally, ELISA results showed a significant improvement in VEGF, TGF-β and TNF-α level in the two models of corneal injury with more effect in the alkaline-induced injury model. Treatment with honey improved corneal alkaline-induced and surgically-induced abrasions in rats and showed anti-inflammatory and anti-angiogenic properties.