3D-printed therapeutic lenses for sustained methylene blue delivery in ocular drug therapy

Contact lenses are attractive platforms for sustained ocular drug delivery, but balancing drug loading, controlled release, and lens performance remains challenging. We developed an optically transparent 3D-printed hydrogel lens platform for controlled delivery of methylene blue (MB), a multifunctional antioxidant and antimicrobial dye. Using vat photopolymerization, HEMA-PEGDA hydrogels with varying monomer ratios were fabricated and compared with commercial silicone hydrogel lenses. Field-emission scanning electron microscopy (FEG-SEM) analysis showed continuous surface morphology in both clear and MB-loaded 3D-printed hydrogel samples, while XRD confirmed the crystalline nature of the MB starting material and the amorphous structure of the HEMA-PEGDA matrix. The printed lens-like prototypes were highly transparent in the visible range, with the H85P15 formulation showing ∼93% light transmission, physiological wettability (contact angle ∼77°), and gel fractions >97%. MB release from commercial and printed lenses was quantified spectrophotometrically and fitted with classical kinetic models. Across all materials, release was best described by the Korsmeyer-Peppas model, indicating anomalous diffusion, with higher HEMA content promoting faster and more extensive release. Printed hydrogels enabled sustained MB delivery for at least 14 days, substantially longer than commercial lenses. Released MB retained concentration-dependent antioxidant activity against H 2 O 2 , confirming the drug's functional stability. Finally, ex vivo experiments on sheep corneas showed that topically applied MB predominantly localized to the epithelium and anterior stroma without disrupting overall tissue architecture. Together, these results demonstrate that vat-printed HEMA-based hydrogels provide a tunable platform for lens-based ocular drug delivery and redox-active therapeutics.