Contact lens-based atropine delivery systems for myopia management: design and in vitro-in vivo evaluation

The prevalence of myopia is increasing exponentially, particularly among children. Alongside other interventions, atropine can slow or even reverse myopia progression; however, topical eye drops produce short-lived concentration peaks that may cause systemic side effects while failing to ensure sustained ocular exposure. Existing contact lens (CL)-based delivery approaches present important limitations, including excessively rapid release, overly prolonged release, or low drug loading. This study aimed to address these shortcomings by designing CLs tailored for atropine delivery during day/night wearing. Hydrogels were synthesized by combining the anionic monomers methacrylic acid (MAA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) with the hydrophobic monomer benzyl methacrylate (BzMA) in specific ratios to modulate affinity for atropine. The resulting materials exhibited suitable solvent uptake, light transmittance, mechanical properties, and oxygen permeability. Anionic monomers enhanced atropine loading, while hydrophobic domains enabled more controlled release. In vivo testing showed that optimized formulations provided sustained drug levels in tear fluid and higher ocular tissue concentrations compared with eye drops. Ocular compatibility was confirmed both in ovo (HET-CAM test) and in vivo. For comparison, atropine loading and release from multifocal CLs designed for myopia control were also evaluated, and in vitro and in vivo correlations were investigated. Overall, these customized CLs represent a promising approach to integrate optical correction with sustained atropine delivery for myopia management.