Aims To determine prevalence of pterygium, its role as main cause of unilateral and bilateral visual impairment and blindness and its impact on refractive errors from adults living in a high ultraviolet exposure area in the Brazilian Amazon Region.
Methods Cluster sampling was used in randomly selecting subjects ≥45 years of age from urban and rural areas of Parintins city. Eligible subjects were enumerated through a door-to-door household survey and invited for an eye exam including refraction. Pterygium was assessed considering location (nasal, temporal or both) and size (<3 mm or ≥3 mm reaching or not pupillary margin).
Results A total of 2384 persons were enumerated and 2041 (85.6%) were examined. Prevalence of pterygium was 58.8% (95% CI 53.8% to 63.7%) and associated with male gender (OR=1.63; 95% CI 1.37 to 1.94; p=0.001), while higher education was a protective factor (OR=0.63; 95% CI 0.44 to 0.92; p=0.018). Older age and rural residence were associated with pterygium ≥3 mm reaching or not pupillary margin, while higher education was a protective factor for pterygium ≥3 mm reaching pupillary margin. Prevalence of pterygium as cause of visual impairment and blindness was 14.3% and 3.9%, respectively. Significantly higher hyperopic refractive errors were found in eyes with pterygium ≥3 mm reaching or not pupillary margin.
Conclusions Pterygium was highly prevalent and the second cause of visual impairment and blindness after provision of refractive correction. Risk factors for pterygium were male gender, advanced age, lower education and rural residency. Strategies to provide pterygium early detection and proper management should be considered by healthcare authorities in this population.
- Visual Impairment
- Refractive Errors
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Contributors AB, AGF, SRS, NNF and SM contributed to the planning, conducting and reporting of the work described in the article. MHM, JMF, MCC, CCC, GCV, PYS, PHM, MJC, JMC, SSW, MC and RBJ contributed to conducting and reporting the work described in the article. All authors reviewed the manuscript.
Funding This work was supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico – CNPQ, Brasilia, Brazil, Programa Ciencias sem Fronteiras (Grant # 402120/2012-4 to SRS, SM and JMF; research scholarships to SRS and RBJ); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP, Sao Paulo, Brazil (Grant # 2013/16397-7 to SRS); SightFirst Program – Lions Club International Foundation (Grant #1758 to SRS), Instituto da Visão, IPEPO, São Paulo, SP, Brazil, Fundação Piedade Cohen, Manaus, AM, Brazil.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The institutional review board/ethics committees from Universidade Federal de São Paulo and from Universidade Federal do Amazonas approved the study protocol.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on request.