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Background: Refractive errors, including myopia, hyperopia, and astigmatism, are the leading causes of visual impairment in school-aged children and can significantly impact their academic performance and quality of life. This study aimed to assess the prevalence of refractive errors among school children from economically disadvantaged areas in Northwest México, using a consistent methodology to facilitate comparison with global data. Methods: We adopted the Refractive Error Study in Children (RESC) protocol by the World Health Organization to examine the prevalence of myopia, hyperopia, and astigmatism. The study comprised a systematic sampling of children aged 6 to 18 years from diverse schools in Northwest México. Trained optometrists conducted visual acuity testing and autorefraction, while ophthalmologists performed cycloplegic refraction to ensure accuracy. Results: The study found a myopia (SE ≤-1.50 D at least one eye) prevalence of 14.55% (95% CI: 13.27-15.91), with a higher incidence in females (6.92%) compared to males (6.00%) in at least one eye. Hyperopia (SE ≥ +1.00 D at least one eye) was less common, at 3.23% (95% CI: 2.61-3.95), with a slightly higher occurrence in males in at least one eye. Astigmatism (Cylinder ≥ 0.75 D at least one eye) was present in 18.63% (95% CI: 17.21-20.12) of the students in at least one eye, with no significant difference between genders. These findings are consistent with other studies in regions such as Puerto Rico and Iran, indicating widespread refractive error issues among schoolchildren. Conclusions: The high prevalence of refractive errors, particularly myopia and astigmatism, highlights the critical need for regular vision screenings in schools and the implementation of public health interventions to provide corrective eyewear. Our study confirms the importance of utilizing standardized methodologies like the RESC protocol to compare refractive error prevalence across different geographical and socio-economic contexts, thereby informing global public health strategies.
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Background: Reliable national estimations for blindness and vision impairment are fundamental to assessing their burden and developing public health policies. However, no comprehensive analysis is available for Mexico. Therefore, in this observational study we describe the national burden of blindness and vision loss by cause and severity during 2019. Methods: Using public data from the Global Burden of Disease (GBD) study 2019, we present national prevalence and years lived with disability (YLDs) counts and crude and age-standardized rates (per 100,000 people) of total, severity- and cause-specific blindness and vision impairment with 95% uncertainty intervals (UIs) by sex and age group. Findings: In Mexico, the burden of blindness and vision impairment was estimated at 11.01 million (95% UI, 9.25-13.11) prevalent cases and 384.96 thousand (259.57-544.24) YLDs during 2019. Uncorrected presbyopia caused the highest burden (6.06 million cases, 4.36-8.08), whereas severe vision loss and blindness affected 619.40 thousand (539.40-717.73) and 513.84 thousand (450.59-570.98) people, respectively. Near vision loss and refraction disorders caused 78.7% of the cases, whereas neonatal disorders and age-related macular degeneration were among the least frequent. Refraction disorders were the main cause of moderate and severe vision loss (61.44 and 35.43%), and cataracts were the second most frequent cause of blindness (26.73%). Females suffered an overall higher burden of blindness and vision impairment (54.99% and 52.85% of the total cases and YLDs), and people >50 years of age suffered the highest burden, with people between 70 and 74 years being the most affected. Interpretation: Vision loss represents a public health problem in Mexico, with women and older people being the most affected. Although the causes of vision loss contribute differentially to the severity of visual impairment, most of the impairment is avoidable. Consequently, a concerted effort at different levels is needed to alleviate this burden. Funding: This study received no funding.
RESUMEN
SIGNIFICANCE: We assessed the prevalence of refractive error in a sample of children of Northern Mexico using the Refractive Error Study in Children protocol of the World Health Organization, which allows for the comparison with other global studies. PURPOSE: Uncorrected refractive error is the main cause of visual impairment in children. The purpose of this study was to assess the refractive error and visual dysfunctions of students (15 to 18 years old) in the upper-middle school system of Sinaloa, Mexico. METHODS: A total of 3468 students in Sinaloa's high school system participated in the study from 2017 to 2019. Optometrists and student clinicians from the Optometry Program of the Autonomous University of Sinaloa conducted the testing. Tests included visual acuities and static retinoscopy. We did not use a cycloplegic agent. RESULTS: The results showed a high prevalence of uncorrected refractive errors. Myopia, defined as a refractive error ≤-0.50 D, had a prevalence of 36.11% (95% confidence interval, 33.47 to 38.83%); hyperopia, defined as a refractive error ≥+2.00 D, had a prevalence of 1.49% (95% confidence interval, 0.09 to 2.33%); and astigmatism, defined as a refractive error with a cylinder ≥0.75 D, had a prevalence of 29.17% (95% confidence interval, 26.60 to 31.76%). We found a significant effect of sex on visual acuity. CONCLUSIONS: Our results are consistent with a high prevalence of myopia reported in adolescents worldwide and in Mexico's northern regions. The results suggest that students attending high school and entering universities should be required to have an optometric eye examination. Additional studies are needed to investigate the prevalence of refractive errors in children in Mexico.