The prevalence of and risk factors for pterygium in an urban Malay population: The Singapore Malay Eye Study (SiMES)

Purpose To determine the prevalence and risk factors for pterygium in the adult Malay population of Singapore. Methods A population-based survey of Malays aged 40 to 79 years living in Singapore was conducted. Pterygium was diagnosed and graded clinically by slit-lamp examination as Grade 1 (atrophic), Grade 2 (intermediate) and Grade 3 (fleshy). We asked about potential risk factors such as socioeconomic status, cigarette smoking and outdoor activity. Results From a total of 4168 eligible subjects, 3280 (78.7%) were examined. There were 508 people with either unilateral (n = 289) or bilateral (n = 219) pterygium. The overall age-standardised prevalence rate of pterygia was 12.3% (95% CI 11.9% to 12.7%). In multiple logistic regression models, pterygium was independently associated with increasing age (OR, 1.3; 95% CI 1.1 to 1.4), male sex (OR, 1.9; 95% CI 1.5 to 2.6) and high systolic blood pressure (OR, 1.6; 95% CI 1.2 to 2.1). Grade 3 pterygium (n = 92) was also associated with cholesterol in the fourth versus the first quartile (p = 0.02) and with male sex. Outdoor occupation is only significant for severe pterygium (p = 0.03). Conclusions The prevalence of pterygium is 12.3% among urban Malays aged 40 years and older and higher than Chinese of similar ages in Singapore. Independent associations of pterygia with increasing age, male sex, outdoor occupations and systemic factors like blood pressure suggest a complex and multi-factorial aetiology for this condition.