To estimate the age-, gender-, and ethnicity-specific prevalence of amblyopia in children aged 5 to 15 years using data from the multi-country Refractive Error Study in Children (RESC).
...Population-based, cross-sectional study.
Among 46 260 children aged 5 to 15 years who were enumerated from 8 sites in the RESC study, 39 551 had a detailed ocular examination and a reliable visual acuity (VA) measurement in 1 or both eyes. Information on ethnicity was available for 39 321 of these participants. This study focused on findings from the 39 321 children.
The examination included VA measurements, evaluation of ocular alignment and refractive error under cycloplegia, and examination of the external eye, anterior segment, media, and fundus.
The proportion of children aged 5 to 15 years with amblyopia in different ethnic cohorts. Amblyopia was defined as best-corrected visual acuity (BCVA) of ≤20/40 in either eye, with tropia, anisometropia (≥2 spherical equivalent diopters D), or hyperopia (≥+6 spherical equivalent D), after excluding children with fundus or anterior segment abnormalities.
The overall prevalence of amblyopia was 0.74% (95% confidence interval, 0.64-0.83) with significant (P < 0.001) variation across ethnic groups: 1.43% in Hispanic, 0.93% in Chinese, 0.62% in Indian, 0.52% in Malay, 0.35% in Nepali, and 0.28% in African children. Amblyopia was not associated with age or gender. The most common cause of amblyopia was anisometropia.
In this study, the prevalence of amblyopia varied with ethnicity and was highest in Hispanic children and lowest in African children. Most cases were unilateral and developed before the age of 5 years. The impact of changes of definitions on prevalence estimates is discussed.
To estimate the nationwide prevalence of visual impairment and associated refractive error in school children in Bhutan. The sample of this prospective cross-sectional national survey comprised of ...randomly selected classes in levels IV-IX (age 10 to 15 years) from schools throughout Bhutan. The examination included measurement of visual acuity (VA), evaluation of ocular motility, refraction under cycloplegia, examination of the external eye, media and fundus. The principal cause of impairment was determined for eyes with uncorrected VA less than or equal to6/12. The main outcome measures were distance VA and cycloplegic refractive error. With a sampling frame of 1967 class-based clusters from 190 schools, 160 classes in 103 schools were randomly selected; 4985 (98.5%) of 5060 enumerated children were examined. The prevalence of uncorrected, presenting, and best-corrected visual impairment (VAless than or equal to6/12) in the better eye was 14.5%, 12.8%, and 0.34%, respectively. Refractive error was the principal cause (94.2%) of impaired vision and 88% of children who could achieve VA greater than or equal to6/9 with best correction were without necessary spectacles. The prevalence of myopia (less than or equal to -0.5 D) was 6.64% and was associated with female gender (P = 0.004), urban schooling (P = 0.002), and greater parental education (P<0.001). The prevalence of hyperopia (greater than or equal to +2.0 D) was 2.17% and was significantly associated with lower class-level (P = 0.033), and female gender (P = 0.025). The overall prevalence of astigmatism (greater than or equal to 0.75 D) was 9.75%. Reduced vision because of uncorrected refractive error is a public health problem among school-age children in Bhutan. Effective school eye health strategies are needed to eliminate this easily treatable cause of visual impairment.
To assess the prevalence of refractive error and visual impairment in school children in a rural area of southern China.
Prospective cross-sectional survey.
Two thousand four hundred children from ...junior high schools in Yangxi County.
Random selection of classes from the 3 junior high school grade levels was used to identify the study sample. Children from 36 classes in 13 schools were examined in April 2005. The examination included visual acuity (VA) testing; ocular motility evaluation; cycloplegic autorefraction; and examination of the external eye, anterior segment, media, and fundus.
Distance VA and cycloplegic refraction.
Among 2515 enumerated children, 2454 (97.6%) were examined. The study population consisted of the 2400 children between 13 and 17 years old. Prevalences of uncorrected, presenting, and best-corrected VA < or = 20/40 in the better eye were 27.0%, 16.6%, and 0.46%, respectively. Sixty percent of those who could achieve acuity > or =20/32 in at least one eye with best correction were without the necessary spectacles. Refractive error was the cause in 97.1% of eyes with reduced vision; amblyopia, 0.81%; other causes, 0.67%; and unexplained causes, 1.4%. Myopia (spherical equivalent, -0.50 diopters D or more in either eye) affected 36.8% of 13-year-olds, increasing to 53.9% of 17-year-olds. Myopia was associated with higher grade level, female gender, schooling in the county urban center, and higher parental education. Hyperopia (+2.00 D or more) affected approximately 1.0% in all age groups. Astigmatism (> or =0.75 D) was present in 25.3% of all children.
Reduced vision because of uncorrected myopia is a public health problem among school-age children in rural China. Effective VA screening strategies are needed to eliminate this easily treated cause of visual impairment.
To contribute to the WHO initiative, VISION 2020: The Right to Sight, an assessment of global vision impairment in 2020 and temporal change is needed. We aimed to extensively update estimates of ...global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990–2020, and forecasts for 2050.
We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. Only studies with samples representative of the population and with clearly defined visual acuity testing protocols were included. We fitted hierarchical models to estimate 2020 prevalence (with 95% uncertainty intervals UIs) of mild vision impairment (presenting visual acuity ≥6/18 and <6/12), moderate and severe vision impairment (<6/18 to 3/60), and blindness (<3/60 or less than 10° visual field around central fixation); and vision impairment from uncorrected presbyopia (presenting near vision <N6 or <N8 at 40 cm where best-corrected distance visual acuity is ≥6/12). We forecast estimates of vision loss up to 2050.
In 2020, an estimated 43·3 million (95% UI 37·6–48·4) people were blind, of whom 23·9 million (55%; 20·8–26·8) were estimated to be female. We estimated 295 million (267–325) people to have moderate and severe vision impairment, of whom 163 million (55%; 147–179) were female; 258 million (233–285) to have mild vision impairment, of whom 142 million (55%; 128–157) were female; and 510 million (371–667) to have visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205–365) were female. Globally, between 1990 and 2020, among adults aged 50 years or older, age-standardised prevalence of blindness decreased by 28·5% (–29·4 to −27·7) and prevalence of mild vision impairment decreased slightly (–0·3%, −0·8 to −0·2), whereas prevalence of moderate and severe vision impairment increased slightly (2·5%, 1·9 to 3·2; insufficient data were available to calculate this statistic for vision impairment from uncorrected presbyopia). In this period, the number of people who were blind increased by 50·6% (47·8 to 53·4) and the number with moderate and severe vision impairment increased by 91·7% (87·6 to 95·8). By 2050, we predict 61·0 million (52·9 to 69·3) people will be blind, 474 million (428 to 518) will have moderate and severe vision impairment, 360 million (322 to 400) will have mild vision impairment, and 866 million (629 to 1150) will have uncorrected presbyopia.
Age-adjusted prevalence of blindness has reduced over the past three decades, yet due to population growth, progress is not keeping pace with needs. We face enormous challenges in avoiding vision impairment as the global population grows and ages.
Brien Holden Vision Institute, Fondation Thea, Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International, and University of Heidelberg.
To assess the prevalence of refractive error and visual impairment in school-age children in a metropolitan area of southern China.
Random selection of geographically defined clusters was used to ...identify children 5 to 15 years of age in Guangzhou. Children in 22 clusters were enumerated through a door-to-door survey and examined in 71 schools and 19 community facilities from October 2002 to January 2003. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy, and autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus.
A total of 5053 children living in 4814 households were enumerated, and 4364 (86.4%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity 20/40 or worse in the better eye was 22.3%, 10.3%, and 0.62%, respectively. Refractive error was the cause in 94.9% of the 2335 eyes with reduced vision, amblyopia in 1.9%, other causes in 0.4%, and unexplained causes in the remaining 2.8%. External and anterior segment abnormalities were seen in 1496 (34.3%) children, mainly minor conjunctival abnormalities. Media and fundus abnormalities were observed in 32 (0.73%) children. Myopia (spherical equivalent of at least -0.50 D in either eye) measured with retinoscopy affected 73.1% of children 15 years of age, 78.4% with autorefraction. The prevalence of myopia was 3.3% in 5-year-olds with retinoscopy and 5.7% with autorefraction. Females had a significantly higher risk of myopia. Hyperopia (+2.00 D or more) measured with retinoscopy was present in 16.7% of 5-year-olds, 17.0% with autorefraction. The prevalence of hyperopia was below 1% in 15-year-olds, with both methods. Astigmatism (cylinder of > or = 0.75 D) was present in 33.6% of children with retinoscopy and in 42.7% with autorefraction.
The prevalence of reduced vision because of myopia is high in school-age children living in metropolitan Guangzhou, representing an important public health problem. One third of these children do not have the necessary corrective spectacles. Effective strategies are needed to eliminate this easily treated cause of significant visual impairment.
To investigate the progression of near vision loss and the cumulative incidence of near vision impairment (NVI) 6 years after initial examination of an urban Chinese cohort.
Population-based, ...prospective cohort study.
People aged ≥35 years examined at baseline in the Yuexiu District of Guangzhou, China.
Participants examined at baseline were invited for 2-year and 6-year follow-up examinations in 2010 and 2014, respectively. Examinations included noncycloplegic autorefraction and binocular near visual acuity (NVA) with and without current near correction measured at 40 cm using a LogMAR ETDRS near vision tumbling E chart. Those with uncorrected binocular NVA (UCNVA) ≤20/40 underwent subjective refraction to obtain best-corrected binocular NVA (BCNVA).
Change in UCNVA between baseline and 2014 follow-up examinations and the 6-year cumulative incidence of vision impairment based on 3 definitions: NVA ≤20/40, ≤20/50, and ≤20/63.
Among the 1817 baseline participants, 1595 (87.8%) were reexamined in 2010 and 1427 (78.5%) in 2014. Mean vision loss between baseline and the 2014 follow-up was 1.54 (±1.74) lines of UCNVA. Vision loss was associated with age 80 years or older, less education, and better baseline UCNVA. The 6-year cumulative incidence of uncorrected binocular NVI (UCNVI) across the 3 vision impairment definitions was 55.2% (95% confidence interval CI, 46.1%-64.3%), 51.3% (95% CI, 44.0%-58.7%), and 42.4% (95% CI, 35.5%-49.3%), respectively. With best-corrected binocular NVI (BCNVI), incidence was 6.89% (95% CI, 4.28%-9.50%), 5.17% (95% CI, 2.89%-7.44%), and 2.62% (95% CI, 1.11%-4.12%), respectively. A higher incidence of UCNVI was associated with worse baseline UCNVA for all 3 impairment definitions. Similarly, incidence of BCNVI was associated with worse baseline BCNVA, but also with older age and education at the primary level or less. Gender was not significant for either UCNVI or BCNVI.
Approximately half of those aged 35 years or older develop UCNVI in 6 years, the overwhelming majority of whom can be corrected with spectacles. Cost-effective strategies to provide spectacles to this at-risk population remains an issue requiring further study.
To investigate the primary causes of visual impairment and blindness in rural China.
Population-based, cross-sectional study.
Geographic cluster sampling was used in randomly selecting residents from ...a rural county/district within 9 provinces in the East Coast, Inland Middle, and West regions of mainland China. Persons aged 50 years or older were enumerated through household visits and invited to examination sites for visual acuity testing and ocular examination. Causes of vision impairment and blindness in 2014 were compared with data from an earlier 2006 survey.
Mild visual impairment (20.4% prevalence) was caused by uncorrected refractive error in two thirds of cases and by cataract in nearly another one fourth; moderate-to-severe visual impairment (10.3% prevalence) was caused by cataract in over onec half of cases and by uncorrected refractive error in another one fifth; blindness (1.66% prevalence) was caused by cataract in approximately one half of cases and in another one fourth by retinal disease. Primary causes of visual impairment and blindness in cataract-operated eyes were uncorrected refractive error, posterior capsule opacity, and retinal disease. From 2006 to 2014, the proportion of visual impairment caused by uncorrected refractive error increased, but rates for unoperated cataract were reduced.
Uncorrected refractive error and unoperated cataract are the 2 primary causes of mild, moderate, and severe visual impairment in rural China, with unoperated cataract and retinal diseases primary causes for blindness. An effective public health strategy to increase service delivery for these causes would lead to substantial reduction in vision impairment and blindness.
To assess the potential of ready-made (spherical) spectacles (RMS) in meeting the need for refractive correction in visually impaired children in China.
Eligible children aged 5-17 years were ...identified from the three study sites in China. Distance visual acuity was measured with a retroilluminated logarithm of the minimum angle of resolution chart with tumbling E optotypes. Cycloplegic autorefraction was performed on all children using a handheld autorefractor. If uncorrected visual acuity (UCVA) was ≤20/40 in either eye, best corrected visual acuity was measured with subjective refractive error. RESULTS : A total of 13 702 children were enumerated from the three studies, with 12 334 (90.0%) having both reliable visual acuity measurements and successful cycloplegia. Among the 12 334 study children, the prevalence of UCVA ≤20/40 in the better seeing eye was 16.4% (95% CI 15.0% to 17.8%), with 91.1% (1843) of these improving by ≥3 lines of visual acuity with refractive correction. Prevalence was 12.7% (95% CI 11.5% to 13.9%) for UCVA
20/50 with 97.4% (1521) improving by ≥3 lines, and 9.38% (95% CI 8.39% to 19.4%) for UCVA ≤20/63 with 98.4% (1138) improving by ≥3 lines. Depending on the severity of visual impairment, 62.8%-64.0% of children could be accommodated with RMS if not correcting for astigmatism of ≤0.75 dioptres and anisometropia of ≤0.50 spherical equivalent dioptres. Approximately 87% of children could be accommodated with RMS if astigmatism and anisometropia limits were increased to ≤1.25 and ≤1.50 dioptres, respectively.
RMS could substantially alleviate visual morbidity in two-thirds or more of visually impaired schoolchildren in China. This cost-effective approach to refractive correction might also be useful in low/middle-income countries with poor access to optometric services.
To estimate the prevalence of vision impairment and blindness in 2014 among older adults in rural China with comparisons with the 2006 Nine-Province Survey.
Population-based, cross-sectional study.
...Geographical cluster sampling was used in randomly selecting residents from a rural county or semi-rural district within 9 provinces: Beijing, Jiangsu, Guangdong, Heilongjiang, Jiangxi, Hebei, Ningxia, Chongqing, and Yunnan. Persons 50 years of age or older were enumerated through household visits and invited to examination sites for visual acuity testing and examination. Vision impairment and blindness in 2014 was compared with data from the 2006 survey.
Among 51 310 examined persons, the prevalence of presenting vision impairment (<20/63 to ≥20/400) in the better-seeing eye ranged from 6.05% to 15.3% across the 9 study sites, with presenting blindness (<20/400) ranging from 0.66% to 5.35%. With best-corrected visual acuity, the prevalence of vision impairment ranged from 1.96% to 8.74%, and blindness from 0.47% to 5.01%. Vision impairment was associated with older age, female sex, and little or no education. The overall prevalence of presenting vision impairment and blindness decreased during the 2006–2014 interval by 6.31% and 29.0%, respectively; and by 16.1% and 38.0%, respectively, after standardization of 2006 prevalence rates to the 2014 population.
Substantial progress has been made in the reduction of vision impairment in rural China. Nevertheless, vision impairment remains an important public health problem with substantial geographic disparities and with older age, female sex, and illiteracy as risk factors.
Correctable vision impairment caused by refractive error is common in the United States population. We estimated the direct costs of providing eyeglasses to all Americans (age> or =12) who need ...refractive correction to achieve good distance vision.
Cross-sectional study of a nationally representative sample of United States citizens.
Participants in the 1999-2002 National Health and Nutrition Examination Survey (NHANES), age > or = 12 years. The NHANES examines a nationally representative sample of the U.S. noninstitutionalized, civilian population.
Presenting and corrected visual acuity data were obtained using an autorefractor from 13,211 (93.0%) of the 14,203 participants who visited the NHANES Mobile Examination Center in 1999 through 2002. Need for refractive correction was defined by current use of corrective lenses for distance vision, improvement to good visual acuity following autorefractor correction (using several cutpoints to define good visual acuity), or both.
Estimates of direct cost for refractive correction (1 pair of complete eyeglasses and a refraction examination) were computed based on Centers for Medicare & Medicaid Services fee schedules for 2000 and also based on expenditure data from the Medical Expenditure Panel Survey.
The NHANES results indicate that >110 million Americans could or do achieve normal vision with refractive correction. The annual direct cost of correcting distance vision impairment is at least $3.8 billion. Of this amount, $780 million represents the annual cost of providing distance vision correction for persons > age 65.
Correctable vision impairment due to refractive error is common in the United States population. These cost estimates provide useful information for public health endeavors aimed at provision of refractive correction to those who need it.
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