Prevalence and Causes of Visual Impairment in Low–Middle Income School Children in São Paulo, Brazil

Abstract

Purpose Assess prevalence and causes of vision impairment among low–middle income school children in São Paulo. Methods Cluster sampling was used to obtain a random sample of children ages 11 to 14 years from public schools (grades 5–8) in three districts from June to November 2005. The examination included visual acuity testing, ocular motility, and examination of the external eye, anterior segment, and media. Cycloplegic refraction and fundus examination were performed in children with uncorrected visual acuity 20/40 or worse in either eye. A principal cause of visual impairment was determined for eyes with uncorrected visual acuity of 20/40 or worse. Results A total of 2825 children were enumerated and 2441 (86.4%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity 20/40 or worse in the better eye was 4.82%, 2.67%, and 0.41%, respectively. Spectacles were used by 144 (5.9%) children. Refractive error was a cause in 76.8% of children with visual impairment in one or both eyes; amblyopia, 11.4%; retinal disorders, 5.9%; other causes, 2.7%; and unexplained causes, 7.7%. Myopic visual impairment (spherical equivalent −0.50 D in one or both eyes) was not associated with age or grade level, but female sex was marginally significant (P = 0.070). Hyperopic visual impairment (+2.00 D or more) was not associated with age, grade level, or sex. Conclusions The prevalence of reduced vision in low–middle income urban São Paulo school children was low, most of it because of uncorrected refractive error. Cost-effective strategies are needed to address this easily treated cause of vision impairment.

Visual acuity and refraction by age for children of three different ethnic groups in Paraguay

“…Most studies, including those done in Brazil, Chile, and Mexico have found a much lower prevalence than our figure for moderate hyperopia (2,(8)(9)(10)(11) . Past studies of refractive errors in children in the U.S. have also looked at ethnicity (2,3) , but the most recent study, the Study, is considered the largest and most diverse study (4) .…”

“…For example, the prevalence of myopia is relatively low in the United States (U.S.) (1)(2)(3)(4) with a range of 4-19% (depending on age and ethnicity), but much higher in Greece (5) at 37%, and highest of all in Taiwan (6,7) with a range of 12-85%, depending on age. In Latin America, a great variance has also been observed with a lower prevalence of myopia in Brazil (4-6%), a higher prevalence in Chile (3-19%), and a very high prevalence in Mexico (75%) (8)(9)(10) . There are multifactorial reasons for these ranges.…”

Prevalence of Eye Diseases and Causes of Visual Impairment in School-Aged Children in Western China

“…Based on a daily life visual acuity in the better eye of worse than 20/40, the prevalence of visual impairment was 7.70%, which was lower than estimates in Chinese children in a different region (10.3%), 7 a Malaysian study (10.1%), and a Chilean report (14.7%), 4 but higher than in a Brazilian report (2.67%), 29 an African study (1.2%), 5 and a Turkish report (1.7%). 33 These findings reminds us that the quality of life of children in western China is a concern.…”

“…29 Ethnicity, geographic location, age, and other population characteristics might have affected the prevalence of strabismus. In addition, in this study, the degree of strabismus was measured only at a short distance, which is another possible reason for the discrepancy between this and other studies.…”

Practical applications to modify and control the development of ametropia

“…(Table 2). [2][3][4][6][7][8][10][11][12]18,19 Although there are suggestions that astigmatism especially 'against-the rule', might have a role in development of myopia, 20 studies on this relationship have been equivocal. 21,22 Significantly, the evolutionary trend with age towards lessening hyperopia or increasing myopia continues for many during childhood with an increasing number of children becoming myopic with each passing year.…”