Global Models of Refractive Error Service Delivery: a review of design, performance, and alignment with WHO SPECS 2030

Abstract

<title>Abstract</title> Background Despite substantial expansion of vision screening and refraction services, effective refractive error coverage (eREC) remains suboptimal, particularly in low- and middle-income countries. This persistent gap reflects systemic shortcomings beyond diagnosis, including weaknesses in spectacle dispensing, affordability, continuity of care, and outcome monitoring. Recent global policy shifts, including adoption of effective coverage indicators and the WHO SPECS 2030 framework, have reframed refractive error (RE) correction as a health-systems performance issue rather than a purely clinical intervention. However, robust comparative evidence identifying service delivery models that most effectively and sustainably improve eREC remains limited. Methods A narrative review was undertaken to examine global RE and optical service delivery models through a health-systems framework. Peer-reviewed literature and authoritative policy documents published between 2000 and March 2025 were systematically synthesised. Identified models were comparatively evaluated across the refractive care continuum using six performance dimensions: access, quality, affordability and equity, continuity of care, sustainability and system integration, and scalability. In addition, models were mapped against the WHO SPECS 2030 pillars, namely services, personnel, education, cost, and surveillance. Results Eight dominant eye-care service delivery models were identified: facility-based public sector services; private optical and social enterprise provision; school-based vision screening with spectacle provision; community outreach and mobile eye-camp services; tele-refraction and digitally enabled services; vision-centre- primary eye care models; public–private partnership (PPP) models; and social enterprise micro-entrepreneurship models. Models emphasizing rapid scale-up of screening and refraction achieved high population reach; however, they demonstrated suboptimal performance in continuity, affordability, surveillance, and sustainability of eREC. In contrast, vision-centre and PPP models showed consistently strong performance across all six evaluative dimensions, including scalability, and exhibited the closest alignment with the WHO SPECS 2030 framework. Across all models, systemic weaknesses namely fragile optical supply chains, limited pooled financing mechanisms, inadequate follow-up systems, and absence of routine outcome monitoring were identified as the key determinants of low effective coverage. Conclusion Achieving universal eREC constitutes primarily a health-systems challenge rather than a diagnostic limitation. The scale-up of refraction services in the absence of integrated dispensing pathways, sustainable financing mechanisms, routine surveillance, and continuity of care frameworks is unlikely to yield durable population-level impact. In contrast, vision-centre-based delivery models and PPP represent the most robust service architectures for delivering equitable, scalable, and sustainable eREC, in alignment with the WHO SPECS 2030 agenda. These models provide clear, actionable guidance for national eye-health policy formulation and programme implementation.