Prevalence of Amblyopia in School-Aged Children and Variations by Age, Gender, and Ethnicity in a Multi-Country Refractive Error Study

Prevalence of amblyopia and strabismus in Hani school children in rural southwest China: a cross-sectional study

PURPOSE

To determine the prevalence rate of amblyopia and strabismus in Chinese Hani ethnic school-aged children.

METHODS

All grade 1 and grade 7 students in Mojiang Hani Autonomous County, located in southwest China, were invited for comprehensive eye examinations performed by experienced ophthalmologists and optometrists, including visual acuity, ocular alignment and movements, cycloplegic autorefraction, anterior segment and fundus examinations. Standard definitions of amblyopia and strabismus were applied to calculate their prevalence rate.

RESULTS

A total of 1656 (91.0% response rate) grade 1 Hani students and 1394 (92.8% response rate) grade 7 Hani students participated in the study. Amblyopia was present in 25 Hani students (0.82%, 95% CI 0.55% to 1.20%), with no significant differences in grade (p=0.42) and gender (p=0.69). Among these 25 amblyopic children, 17 had unilateral amblyopia and eight had bilateral amblyopia, including 16 anisometropic, eight binocular refractive and one strabismic. Strabismus was found in 59 Hani students (1.93%, 95% CI 1.50% to 2.48%), including 47 with intermittent exotropia, six with constant exotropia, five with constant esotropia and one with unilateral superior oblique palsy. The prevalence rate of strabismus was higher in grade 7 students than grade 1 students with borderline significance (2.44%vs1.50%, p=0.07), but was similar by gender (2.16% in boys vs 1.68% in girls, p=0.36).

CONCLUSION

The prevalence of amblyopia and strabismus in Chinese Hani school children are both lower than that previously reported for Chinese Han children in China and for many other racial/ethnic populations from non-China studies. Refractive error is the major cause for amblyopia and intermittent exotropia is the primary strabismus type.

Visual Impairment and Eye Disease Among Children of Migrant Farmworkers

PURPOSE

To determine the prevalence of reduced visual acuity and ocular disease in the children of migrant farmworkers in Georgia.

METHODS

A retrospective chart review of data acquired by a vision screening was performed on 156 Haitian and Hispanic children of migrant farmworkers attending a summer school in Georgia. Reduced visual acuity at presentation was analyzed and stratified by ethnicity, type of ocular disease, and immediate resolution with refractive correction.

RESULTS

The authors found that 20% of migrant farmworker children have a high prevalence of reduced visual acuity in the worse eye. Of those with worse-eye reduced visual acuity, 83% had uncorrected refractive error. The prevalence of uncorrected refractive error from astigmatism and high astigmatism was significantly higher among Hispanics than Haitians. The prevalence of amblyopia suspects among migrant farmworker children was 3%. Of the amblyopia suspects, 80% were anisometropic.

CONCLUSIONS

Children of migrant farmworkers in Georgia have a higher rate of reduced visual acuity, largely from uncorrected refractive error, when compared to other Hispanic and African American children in the United States with a prevalence more aligned to children in Asian and Latin American countries than school children in the United States. This illustrates the need for improved access to screening and care in this vulnerable population. [J Pediatr Ophthalmol Strabismus. 2019;56(1):28-34.].

The prevalence of amblyopia in Iran: A systematic review

PURPOSE

The aim of this study was to determine the prevalence of amblyopia in the population of Iran.

METHODS

This article is a systematic review. A comprehensive search was conducted in PubMed, Scopus, Science Direct, Ovid, Web of Science, SID, Magiran, with appropriate terms. Information related to the sample size and the prevalence of amblyopia was extracted and summarized in tables. Analysis was performed using STATA software.

RESULTS

From 551 articles that were originally extracted from the databases, 31 articles met the criteria for entering the review. These studies were conducted in different regions of Iran. The prevalence of amblyopia in different regions varied between 0.19 and 3.69%. Study results were heterogeneous (I2 = 99.7%), and therefore, a meta-analysis was not done.

CONCLUSIONS

The prevalence of amblyopia in Iran is very different. In addition to conducting national screenings, it is necessary to report the incidence of amblyopia and its related factors in different parts of the country.

Global and regional estimates of prevalence of amblyopia: A systematic review and meta-analysis

Background: Amblyopia is one of the most important causes of vision impairment in the world, especially in children. Although its prevalence varies in different parts of the world, no study has evaluated its prevalence in different geographical regions comprehensively. The aim of the present study was to provide global and regional estimates of the prevalence of amblyopia in different age groups via a systematic search.Methods: In this study, international databases, including Embase, Scopus, PubMed, Web of Science, and other relevant databases, were searched systematically to find articles on the prevalence of amblyopia in different age groups published in English. The prevalence and 95% CI were calculated using binomial distribution. The Cochran's Q-test and I² statistic were applied to assess heterogeneity, a random-effects model was used to estimate the pooled prevalence, and a meta-regression method was utilized to investigate the factors affecting heterogeneity between studies.Results: Of 1252 studies, 73 studies were included in the analysis (sample volume: 530,252). Most of these studies (n = 25) were conducted in the WHO-Western Pacific Regional Office. The pooled prevalence estimate of amblyopia was 1.75% (95% CI: 1.62-1.88), with the highest estimate in European Regional Office (3.67%, 95% CI: 2.89-4.45) and the lowest in African Regional Office (0.51%, 95% CI: 0.24-0.78). The most common cause of amblyopia was anisometropia (61.64%). The I² heterogeneity was 98% (p < 0.001). According to the results of univariate meta-regression, the variables of WHO region (b: 0.566, p < 0.001), sample size (b: -0.284 × 10^-4, p: 0.025), and criteria for definition of amblyopia (b: -0.292, p: 0.010) had a significant effect on heterogeneity between studies, while age group, publication date, and cause of amblyopia had no significant effect on heterogeneity.Conclusion: The prevalence of amblyopia varies in different parts of the world, with the highest prevalence in European countries. Geographical location and criteria for definition of amblyopia are among factors contributing to the difference across the world. The results of this study can help stakeholders to design health programs, especially health interventions and amblyopia screening programs.

Vision screening at two years does not reduce the prevalence of reduced vision at four and a half years of age

BACKGROUND

There is currently insufficient evidence to recommend vision screening for children < 36 months of age. This study assessed the effect of comprehensive vision screening, as well as the sensitivity of age-appropriate vision tests, at two years of age on habitual visual acuity at 4.5 years of age.

METHODS

Children born at risk of neonatal hypoglycaemia (n = 477) underwent vision assessment at 54 ± 2 months of age including measurement of monocular and binocular habitual visual acuity, assessment of binocularity and stereopsis. Of these children, 355 (74.4 per cent) had also received vision screening at two years of age (mean age = 24± 1 months), while 122 were not screened.

RESULTS

Eighty (16.8 per cent) children were classified as having reduced vision at 4.5 years of age, but the prevalence of reduced vision did not differ between children who had previously been screened at two years of age and those who had not (15.5 per cent versus 20.5 per cent, p = 0.153). However, children with reduced vision at 4.5 years of age were more likely to have had visual abnormalities requiring referral detected at two years of age (p = 0.02). Visual acuity and mean spherical equivalent autorefraction measurements were also worse (higher values) in two-year-old children who were later classified with reduced habitual visual acuity (p = 0.031 and p = 0.001, respectively). Nevertheless, unaided binocular visual acuity, non-cycloplegic refractive error, and stereopsis at two years all showed poor sensitivity and specificity for predicting visual outcomes at 4.5 years of age.

CONCLUSION

Our findings do not support the adoption of early vision screening in children as current vision tests suitable for use with two-year-old children have poor sensitivity for predicting mild-moderate habitual vision impairment at 4.5 years of age.

Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses

OBJECTIVE

To determine the prevalence of, associations with and diagnoses leading to mild visual impairment or worse (logMAR >0.3) in middle-aged adults in the UK Biobank study.

METHODS AND ANALYSIS

Prevalence estimates for monocular and binocular visual impairment were determined for the UK Biobank participants with fundus photographs and spectral domain optical coherence tomography images. Associations with socioeconomic, biometric, lifestyle and medical variables were investigated for cases with visual impairment and matched controls, using multinomial logistic regression models. Self-reported eye history and image grading results were used to identify the primary diagnoses leading to visual impairment for a sample of 25% of cases.

RESULTS

For the 65 033 UK Biobank participants, aged 40-69 years and with fundus images, 6682 (10.3%) and 1677 (2.6%) had mild visual impairment or worse in one or both eyes, respectively. Increasing deprivation, age and ethnicity were independently associated with both monocular and binocular visual impairment. No primary diagnosis for the recorded level of visual impairment could be identified for 49.8% of eyes. The most common identifiable diagnoses leading to visual impairment were cataract, amblyopia, uncorrected refractive error and vitreoretinal interface abnormalities.

CONCLUSIONS

The prevalence of visual impairment in the UK Biobank study cohort is lower than for population-based studies from other industrialised countries. Monocular and binocular visual impairment are associated with increasing deprivation, age and ethnicity. The UK Biobank dataset does not allow confident identification of the causes of visual impairment, and the results may not be applicable to the wider UK population.

The prevalence of visual disorders in Iranian students: A meta-analysis study and systematic review

Background

Visual defects have dramatic effects on health, self-esteem, and educational function of students, and delayed diagnosis will cause complications, like academic failure and psychologic disorders.

Objective

The present study aimed to investigate the prevalence of ocular disorders in Iranian students in a systematic review.

Methods

We searched databases, including PubMed, SID, Magiran, Google Scholar, and Iranmedex using the following keywords in Persian and English: disorders, vision, amblyopia, refractive errors, astigmatism, student, and Iran with all the possible combinations, important, chief, and sensitive words. Search resulted in 28 articles, conducted during a period from 1996 to 2014 in Iran and their data was analyzed using meta-analysis and random effects model. Heterogeneity of studies was assessed using I2 index, and data was finally analyzed with R Software and STATA (Version 11.2).

Results

Total number of subjects in the study was 1,117,274, aged 2 to 18 years. The prevalence of disorders related to amblyopia, refractive error, and strabismus was 8%, 7% and 1%, respectively. The greatest amount of refractive error was related to astigmatism (19%) followed by myopia (17%).

Conclusion

According to the study results, the prevalence of visual disorders among Iranian students indicated the critical necessity of screening programs for prevention of visual disorders in this age group.

The burden of pure anisometropic amblyopia: a cross-sectional study on 2800 Iranians

PURPOSE

To assess the proportion of pure anisometropic amblyopia in a sample Iranian (white) population.

METHODS

A total of 2800 consecutive individuals who presented at a referral eye clinic for any reason were examined for the presence of pure anisometropic amblyopia. Anisometropia was reported when a spherical equivalent refraction difference of at least 1.0 D with or without a cylinder refraction difference of at least 1.0 D was present between the two eyes. Amblyopia was defined as the best-corrected visual acuity of 20/30 or worse or a two-line interocular visual acuity difference between eyes that could not be attributed to any structural ocular pathology or visual pathway abnormality.

RESULTS

Subjects were 1528 females and 1272 males with a mean age of 30.25 ± 14.93 years (range, 5-65). Amblyopia was diagnosed in 192 cases (6.9%), significantly more frequent among females (7.9 vs. 5.7%, p = 0.02). Pure anisometropic amblyopia was present in 6.1% of the study population, significantly more common in patients with spherical hyperopic anisometropia (37.7%) compared to patients with spherical myopic anisometropia (21.3%), cylindrical myopic anisometropia (4.1%), and cylindrical hyperopic anisometropia (15%) (p < 0.001).

CONCLUSIONS

Pure anisometropic amblyopia is a common finding in Caucasians seeking eye care, particularly when anisometropia is of spherical hyperopic subtype.

The prevalence of uncorrected refractive error in urban, suburban, exurban and rural primary school children in Indonesian population

Uncorrected refractive error (URE) is a major health problem among school children. This study was aimed to determine the frequency and patterns of URE across 4 gradients of residential densities (urban, exurban, suburban and rural). This was a cross-sectional study of school children from 3 districts in Yogyakarta and 1 district near Yogyakarta, Indonesia. The information regarding age, sex, school and school grader were recorded. The Snellen's chart was used to measure the visual acuity and to perform the subjective refraction. The district was then divided into urban, suburban, exurban and rural area based on their location and population. In total, 410 school children were included in the analyses (urban=79, exurban=73, suburban=160 and rural=98 school children). Urban school children revealed the worst visual acuity (P<0.001) and it was significant when compared with exurban and rural. The proportion of URE among urban, suburban, exurban and rural area were 10.1%, 12.3%, 3.8%, and 1%, respectively, and it was significant when compared to the proportion of ametropia and corrected refractive error across residential densities (P=0.003). The risk of URE development in urban, suburban, exurban, and rural were 2.218 (95%CI: 0.914-5.385), 3.019 (95%CI: 1.266-7.197), 0.502 (95%CI: 0.195-1.293), and 0.130 (95%CI:0.017-0.972), respectively. Urban school children showed the worst visual acuity. The school children in urban and suburban residential area had 2 and 3 times higher risk of developing the URE.

Amblyopia and strabismus: trends in prevalence and risk factors among young adults in Israel

Aims

To estimate the prevalence of amblyopia, present strabismus and amblyopia risk factors (ARFs) among young adults in Israel and to analyse trends over time of prevalence rates.

Methods

We conducted a cross-sectional study including 107 608 pre-enlistees aged 17.4±0.6 years born between 1971 and 1994. Across the birth years, the following trends of prevalence rates among young adults were analysed: prevalence of amblyopia, prevalence of strabismus, severity of amblyopia and prevalence of ARFs (strabismsus, anisometropia and isoametropia). Unilateral amblyopia was defined as best corrected visual acuity (BCVA) of <0.67 (6/9) in either eye or as an interocular difference of two lines or more. Bilateral amblyopia was defined as BCVA of <0.67 (6/9) in both eyes. The severity of amblyopia was classified as mild (BCVA ≥0.5 [6/12]), moderate (BCVA <0.5 [6/12] and ≥0.25 [6/24]) or severe (BCVA <0.25 [6/24]).

Results

The prevalence of young adulthood amblyopia declined by 33%, from 1.2% to 0.8% (R2=0.87, p<0.001) across 24 birth years. This decline may be due to a drop in unilateral amblyopia from 1% to 0.6% (R2=0.93, p<0.001), while the prevalence of bilateral amblyopia remained stable (0.2%, p=0.12). The decline in amblyopia was apparent in mild and moderate amblyopia, but not in severe amblyopia. Strabismus and anisometropia were detected in 6–12% and 11–20% of subjects with unilateral amblyopia, respectively, without significant trends. Strabismic amblyopia remained constant in the entire population across years. Isoametropia was detected in 46–59% of subjects with bilateral amblyopia without a significant trend across birth years. Prevalence of strabismus in the study population decreased by 50%, from 1.2% to 0.6% (R2=0.75, p<0.001). In subjects with present strabismus, the prevalence of mild unilateral amblyopia increased, while moderate or severe unilateral amblyopia remained relatively stable.

Conclusion

Among young adults, the prevalence of unilateral amblyopia, as well as the prevalence of present strabismus, decreased significantly over a period of a generation. The prevalence of strabismic, bilateral or severe (both unilateral and bilateral) amblyopia remained stable. The establishment of the national screening programme for children and the improved utility of treatment for amblyopia and strabismus coincide with these trends. Thus, it is possible that these early interventions resulted in modification of the ‘natural history’ of these conditions and their prevalence in adolescence.

Vision screening in children: Is 7-9 years of age a threshold for visual impairment?

OBJECTIVE

The present study aimed to assess the prevalence of decreased visual acuity, strabismus, and spectacle wear in children aged 5 to 13 years.

METHODS

A cross-sectional study was performed in primary education schools. A total of 1938 participants, including 940 females (48.5%) and 998 males (51.5%) with a mean age 8.96 ± 2.31 (5-13 years old), were screened. The comparisons were performed with gender, age, and age groups. The children attended to vision screening were assigned to three age groups as 5-6 years, 7-9 years, and 10-13 years.

RESULTS

The prevalence of the parameters was detected as decreased visual acuity 12.4%, strabismus 2.2%, and spectacle wear 6.9%. The prevalence of decreased visual acuity was significantly higher in girls and in children aged 7-9 years old (p = 0.013, p < 0.001). The prevalence of spectacle wear was significantly higher in girls and in children aged 7-9 years old (p = 0.019, p < 0.001). There was a visual acuity decrease in 33 of 106 (31.1%) children despite wearing own spectacle. There was no significant difference among three age groups for strabismus.

CONCLUSION

Increased prevalence of decreased visual acuity, as well as the higher frequency of spectacle wear in children at ages of 7-9 years old may point out a threshold for visual impairment.