Polyoxyethylene and polypropylene emulsification enhances retinol palmitate efficacy in corneal wound healing

Retinol palmitate (VApal), an active ingredient in ophthalmic solution, has been reported to repair corneal injuries. Additionally, it has been suggested that the efficacy of VApal is enhanced by a specific surfactant, polyoxyethylene-polypropylene [EO₁₀₀PO₇₀EO₁₀₀ (EOPO)]. We aimed to determine the efficacy of VApal in corneal wound healing in comparison to that of hyaluronic acid (HA), carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC) used in over-the-counter ophthalmic solutions and whether the efficacy of VApal could be enhanced by EOPO compared to the widely used surfactant, polyoxyethylene hydrogenated castor oil 60 (HCO60). To evaluate the efficacy of VApal or VApal emulsified with a surfactant, we performed a wound healing assay using corneal epithelial cells in monolayer (n = 4) or 3D culture (n = 6). Wound closure rates were calculated each time, and the efficacy was compared using the time to reach a 50% wound closure rate (ET50). The ET50 values of VApal, HA, CMC and HPMC were approximately 17.31 h, 26.99 h, 28.98 h and 26.01 h respectively. The ET50 values of VApal emulsified with EOPO or HCO60 were 34.49 h and 43.31 h, respectively. In conclusion, VApal is more beneficial than other ingredients for corneal wound healing. Additionally, the efficacy of VApal can be enhanced using EOPO instead of HCO60.