Hyperopia: a meta-analysis of prevalence and a review of associated factors among school-aged children

Methodological quality of the review: Low confidence

Author: Victor Delpizzo Castagno, Anaclaudia Gastal Fassa, Maria Laura Vidal Carret, Manuel Augusto Pereira Vilela and Rodrigo Dalke Meucci

Region: China, Hong Kong, Malaysia, Nepal, Cambodia, Vientiane, India, Iran, Australia, Finland, United Kingdom (UK), South Africa, Chile, Poland, USA, Mexico, Sweden

Sector: Myopia

Subsector: Epidemiology of hyperopia

Equity focus: No

Study population: Children

Type of programme: School based

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Hyperopia in childhood, particularly when severe and/or associated with accommodative and binocular dysfunctions, may be a precursor of visual motor and sensory sequelae, such as accommodative esotropia, anisometropia and unilateral or bilateral amblyopia. Although there are several studies on hyperopia, so far there has been no systematic review of the subject.

Objectives: The aim of this study was to assess the efficacy and safety of timolol in the treatment of myopic regression after laser in situ keratomileusis (LASIK).

Main findings: This review included 40 cross-sectional studies on prevalence and/or assessment of risk factors for hyperopia. All samples of children used in the studies were population-based or school-based, except the study that used a sample of children from a private school. In most studies included in this review, the cut-off point for hyperopia was based on the Refractive Error Study in Children (RESC) protocol used in multicentre studies. The meta-analysis indicates that hyperopia prevalence decreases as age increases, with a summary prevalence measure of 5% at age 7, 2-3% between age 9 and 14 and around 1% at age 15. Various studies of children aged 6 to 8 presented large confidence intervals. I² indicates homogeneity among the studies regarding specific age. In studies using the 5-15 age group and ≥ +2.00 D (RESC) cut-off, hyperopia prevalence ranged from 2.1% to 19.3%. Most studies showed no statistically significant association between gender and hyperopia. There is also evidence that Caucasian children are more hyperopic than African-American, Black and Asian (East and South Asia). Most of the reviewed studies showed no significant association between parental education and hyperopia in children. The frequency of hyperopia is higher among White children and those who live in rural areas. There is no consensus about the association between hyperopia and gender, family income and parental schooling.

Methodology: Inclusion criteria included population-based or school-based studies assessing hyperopia through cycloplegic autorefraction or cycloplegic retinoscopy. The literature search was performed on Medline (PubMed), Scielo, Bireme, Embase, the Cochrane Library, Clinical Trials registration website and WHO databases. The meta-analysis was performed using a Microsoft Excel spreadsheet. Differences in the populations studied, especially ethnicity, have a non-random impact on prevalence. The random effects model was therefore used in order to obtain the effect summary and its confidence interval. The adequacy of the effect summary depends on the homogeneity assumption. Heterogeneity was measured using the Q test and was quantified using I² Heterogeneity tests having a P-value <0.1 were considered statistically significant. This systematic review was performed according to the PRISMA and MOOSE Statements. The study was approved by the Federal University of Pelotas School of Medicine Research Ethics Committee and follows the Declaration of Helsinki guidelines.

Applicability/external validity: Not discussed.

Geographic focus: Not discussed.

Summary of quality assessment:

There is low confidence in the conclusions about the effects of this study, as important limitations were identified. Thorough searches of the literature were not comprehensive enough to ensure that all relevant studies were identified; in addition, the search period was not reported. It is not clear on the methods used to assess the risk of bias of included studies. In addition, authors do not specify if biases were avoided at screening and data extraction stages of the review.