Abstract
Purpose: :
Refractive errors are important causes of visual impairment. Myopia, in particular, has reached "epidemic" proportions in Asian cities. There are few studies on prevalence of refractive errors in children, especially before school-going age. We aim to describe the prevalence rates of refractive errors in preschoolers and their associations.
Methods: :
A cross-sectional study was conducted among 798 preschoolers aged 3 to 6 years in 4 Singapore kindergartens. Visual acuities and refractive errors were measured by LogMAR charts and cycloplegic autorefraction respectively. Parents completed a questionnaire providing social demographic data and family history of myopia. Spherical equivalent (SE) was defined as sphere power + 0.5 negative cylinder. Myopia was defined as SE ≤-0.50D, hypermetropia as SE ≥+1.00D, anisometropia as ≥1.00D difference between SEs of both right and left eyes, and astigmatism as negative cylinder power ≤1.00D.
Results: :
A response rate of 80.2% was achieved. 68.6% were emmetropes. Overall mean refractive error was +0.29D. Astigmatism (26.3%, 95%CI=22.8-29.7) was the most common refractive error, followed by hypermetropia (18.0%, 95%CI=14.9-21.0), myopia (13.4%,95%CI=10.7-16.1), anisometropia (3.9%, 95%CI=2.4-5.4). Prevalence rates of astigmatism decreased with higher income (p=0.034). Astigmatism was significantly associated with myopia of -2.99D ≤ SE ≤ -0.50D (p<0.001). The prevalence of myopia was higher in boys (p=0.037) for SE ≤-0.50D. Myopia rates increased with family history of myopia. Hypermetropia had significantly higher rates in non-Chinese(p=0.025), in contrast to anisometropia.
Conclusions: :
The most common refractive error in Singapore preschoolers is astigmatism, followed by hypermetropia, myopia and lastly anisometropia. Astigmatism was associated with lower income and myopia. Myopia was associated with positive family history. Anisometropia was associated with Chinese race. The high prevalence of refractive errors in Singapore preschoolers constitutes a major public health problem, which left uncorrected, can cause significant visual impairment.
Keywords: refractive error development • clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment