Effect Of Post-Alkali Injury Lycium Barbarum Polysaccharide (Lbp) Topical Treatment On Reducing Corneal Haze And Promoting Corneal Epithelial Healing

This study aims to investigate the efficacy of topical Lycium barbarum polysaccharide (LBP) post-injury treatment in minimising corneal haze and accelerating corneal epithelial healing, utilising an in vivo mice model of alkali-induced epithelial-stromal injury.

Corneal haze, a significant cause of visual impairment, is a possible complication from refractive surgeries. Conventional treatments for corneal haze consist of corticosteroids and Mitomycin-C, which are associated with severe side effects, including increased intraocular pressure and induction of scleral necrosis. Lycium barbarum polysaccharide (LBP), a wolfberry extract, has been found to reduce corneal fibrosis in vitro, indicating its anti-fibrotic potential for corneal haze treatment.

In vivo mice model of alkali-induced corneal epithelial-stromal injury was developed. Mice of C57Bl/6J wild-type strain was used. Alkali injury of the right cornea was induced by applying 0.5M NaOH onto the centre of cornea via 1.5mm diameter filter paper, with mice under anaesthesia. The injury time was set to 45 seconds, followed by corneal rinsing with filtered water. Topical application of either 2mg/mL or 20mg/mL LBP was conducted daily for seven consecutive days after alkali injury. PBS was used for the control group. Corneal haze was evaluated by slit-lamp microscopy on Day 0, 1, 2, 3, 7, 14, 21, and 28, quantified by Modified Fantes score (0-4). Epithelial damage was assessed by fluorescein staining under cobalt blue light.

All corneas developed mild corneal haze with a Modified Fantes Score of 2 immediately after alkali injury. This validated the consistency of in vivo mice alkali injury model in corneal haze induction with 0.5M NaOH. Modified Fantes Score on Day 28 of PBS-treated, 2mg/mL LBP-treated, and 20mg/mL LBP-treated (n=3 each) were 3, 2.67, and 3 respectively. However, the difference was not statistically significant. Regarding epithelial healing, all corneas achieved re-epithelialisation on Day 3 after injury. The difference in inter-group estimated epithelial defect area was not statistically significant at all timepoints.

Current data suggests that topical treatment of 2mg/mL and 20mg/mL LBP after corneal injury did not reduce corneal haze and promote epithelial healing compared to control.  This might be due to limited LBP penetrance from topical administration route and short duration of treatment. Further investigations with a larger sample size are needed to maximise the study outcomes.