Clinic-based prevalence of uncorrected refractive errors and associated visual impairment: a nationwide cross-sectional study of 3.6 million outpatients in Mexico

Background Uncorrected refractive errors (UREs) are the predominant cause of vision impairment and blindness worldwide, despite the availability of eyeglasses as a cost-effective intervention. Sociocultural factors, including restricted access to healthcare and inadequate self-care education, exacerbate the burden of UREs. There is a paucity of studies evaluating UREs in Mexico with comprehensive national coverage across various age groups. This clinic-based study aimed to assess the profile of UREs and associated visual impairment (VI) in Mexico using a substantial sample of individuals seeking care at a large nationwide outpatient network. Methods We evaluated UREs and URE-related VI by analyzing eye examination data from 3.6 million outpatients who attended Salud Digna clinics in 2024. Results The national clinic-based prevalence of UREs was 26.5% (980,718 affected individuals, 95% CI:26.5%-26.59%), highest in Baja California Sur state (6,515 affected individuals, 43.8%, 95% CI:42.99%-44.59%), among males aged 40–49 years (71,002 affected individuals, 34.1%, 95% CI:33.91%-34.32%), and females under 10 years (17,132 affected individuals, 32.3%, 95% CI:31.88%-32.67%). Clinic-based prevalence of uncorrected astigmatism, uncorrected hyperopia, uncorrected hyperopia-astigmatism, uncorrected myopia, and uncorrected myopia-astigmatism were 1.3% (48,978 affected individuals, 95% CI:1.31%-1.34%), 10.2% (376,701 affected individuals, 95% CI:10.16%-10.23%), 1.7% (61,171 affected individuals, 95% CI:1.64%-1.67%), 6.4% (235,285 affected individuals, 95% CI:6.34%-6.39%), and 7% (258,583 affected individuals, 95% CI:6.97%-7.02%), with highest rates in Tlaxcala (444 affected individuals, 3.9%, 95% CI:3.54%-4.26%), Tabasco (10,235 affected individuals, 20%, 95% CI:19.66%-20.35%), Baja California Sur (673 affected individuals, 4.5%, 95% CI:4.2%-4.87%), Zacatecas (3,149 affected individuals, 10.2%, 95% CI:9.85%-10.52%), and Tlaxcala (1,504 affected individuals, 13.17%, 95% CI:12.55%-13.8%). The national URE-related VI clinic-based prevalence was 0.89% (32,962 affected individuals, 95% CI:0.88%-0.9%), highest in Hidalgo state (527 affected individuals, 1.8%, 95% CI:1.63%-1.93%) and among those over 80 years (1,457 affected males, 6%, 95% CI:5.97%-6.59%; 2,206 affected females, 5.8%, 5.83%-6.33%). The national clinic-based prevalence of mild, moderate, and severe visual impairment was 0.62% (22,858 affected individuals, 95% CI:0.61%-0.63%), 0.26% (9,683, 95% CI:0.26%-0.27%), and 0.01% (421 affected individuals, 95% CI:0.01%-0.01%). Conclusions This outpatient-based study highlights the clinic-based prevalence of UREs and related VI in Mexico, emphasizing the need for improved access to eye care services.