Curcumin Nanoemulsion: Characterization and Effect on Cataracts in an In Vivo Animal Model and Ex Vivo Human Model

Cataracts are the leading cause of reversible blindness worldwide; this condition results from the aggregation of lens proteins. Currently, surgery remains the only treatment; however, there is growing interest in non-surgical approaches, including the use of bioactive compounds incorporated into nanostructured systems designed to enhance solubility, enable controlled release, and improve bioavailability and bioactivity. Among the bioactive compounds investigated, curcumin has attracted considerable attention due to its antioxidant and anti-inflammatory properties, positioning it as a potential anticataractogenic agent. In the present study, curcumin-loaded nanoemulsion was developed via ultrasonication and characterized by average particle size, D90 percentile, ζ potential, and rheological behavior. In addition, its anti-cataract efficacy was evaluated both using an in vivo model in rats and an ex vivo model employing human cataract samples. The resulting curcumin-loaded nanoemulsion exhibited an average particle size of 152 ± 19.79 nm with a monomodal distribution, along with good physical stability over time. The nanoemulsion exhibited apparent viscosity between 30 and 25 mPa·s, at shear rate values (100 to 0 s^-1), indicating slight shear-thinning behavior. Regarding the effect on cataracts, in the in vivo model, cataract reversal was observed. Furthermore, ex vivo isothermal titration calorimetry (ITC) analyses indicated exothermic heat exchange between the curcumin nanoemulsions and cataract fragments, consistent with binding interactions occurring within lens components, likely involving crystallin proteins. These findings provide biophysical and in vivo evidence that intravitreally administered curcumin-loaded nanoemulsions not only prevent but actively reverse lens opacity, positioning them as a promising non-surgical therapeutic approach for cataract treatment.