Defocus Spectacle Lenses for Myopia Control in Children: Design, Fitting, Compliance, and Long-term Outcomes

The global prevalence of childhood myopia is escalating, necessitating effective and non-invasive interventions to mitigate axial elongation and associated pathologies. Defocus spectacle lenses (DSLs), a category encompassing technologies such as Defocus Incorporated Multiple Segments (DIMS), Highly Aspherical Lenslets (HAL), and Cylindrical Annular Refractive Elements (CARE), have emerged as primary management strategies. Unlike conventional single-vision lenses, DSLs utilize specific optical geometries to impose a myopic defocus on the peripheral retina to inhibit eye growth, while maintaining clear central vision. This narrative review synthesizes evidence from randomized controlled trials (RCTs), long-term extension studies, and real-world datasets published until late 2025. We critically evaluated the optical designs, clinical efficacy, fitting protocols, compliance determinants, and safety profiles. Converging evidence from pivotal RCTs demonstrates that DIMS and HAL designs reduce myopia progression and axial elongation by approximately 50–60% over 2–3 years compared to single-vision lenses. Long-term data extending to 6 years for DIMS and 5 years for HAL suggest sustained efficacy with minimal rebound observed upon discontinuation, although the evidence remains limited. Emerging designs utilizing alternative mechanisms, such as contrast modulation (Diffusion Optics Technology [DOT]) and geometric phase/quality variations (e.g., CARE), also show promising efficacy. Combination therapies, particularly DSLs with low-dose atropine, have shown additional benefits for rapid progressors. Nonetheless, real-world effectiveness is heavily dependent on compliance (targeting approximately 12 h/day) and precise fitting parameters. Currently, DSLs are a well-established, scalable, and generally safe approach for myopia control. Future clinical practice should prioritize rigorous fitting standards, objective compliance monitoring, and personalized treatment selection, based on individual progression risks and optical profiles.