Influence of Distance and Near Visual Impairment on Self-Reported Near Visual Functioning in a Multinational Study.

PURPOSE: To assess the influence of distance and near visual impairment on self-reported near visual functioning (VF) in a multinational study. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Participants aged 35 years or older were selected randomly with cluster sampling at 7 sites: rural sites in Nepal (Kaski) and India (Madurai), a semirural site in China (Shunyi), semiurban sites in South Africa (Durban) and Niger (Dosso), and urban sites in the United States (Los Angeles) and China (Guangzhou). METHODS: Binocular presenting distance and near visual acuity (VA) were measured with a logarithm of the minimum angle of resolution tumbling E chart at 4 m and 40 cm, respectively. A 12-item near VF questionnaire interview was administered by trained local interviewers, with responses scored from 100 to 0 as visual disability increased. Multiple linear regression was used to investigate the association of age, gender, education, and VA with overall eyesight, difficulty with activities, and social functioning subscale scores. MAIN OUTCOME MEASURES: Visual functioning subscale scores. RESULTS: The study sample consisted of 6851 questionnaire respondents. The VF subscale scores decreased significantly with worse distance and near VA, and even mildly impaired VA could result in reduced VF. Lower VF subscale scores were associated with older age at 4 sites, female gender at 3 sites, and greater education at 2 sites. The influence of near VA was greater than distance VA at 3 sites, and at 1 site, distance VA was more influential than near VA. With study site included in the regression modeling, lower scores for the overall eyesight subscale (compared with the Shunyi reference site) were found in Guangzhou, Kaski, and Durban; lower difficulty in activities scores were found in Kaski and Durban, but better scores were found in Guangzhou and Madurai; and social functioning scores were lower in Kaski, Durban, and Dosso. CONCLUSIONS: Along the entire VA spectrum, lower levels of distance and near VA led to significant reductions in VF subscale scores, with wide variation both within and between study sites. The impact of near vision on VF should receive greater emphasis with further investigation in various socioeconomic and cultural settings.

Visual impairment and refractive error in school children in Bhutan: The findings from the Bhutan School Sight Survey (BSSS 2019).

PURPOSE: To estimate the nationwide prevalence of visual impairment and associated refractive error in school children in Bhutan. METHODS: 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 ≤6/12. The main outcome measures were distance VA and cycloplegic refractive error. RESULTS: 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 (VA≤6/12) 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 ≥6/9 with best correction were without necessary spectacles. The prevalence of myopia (≤ -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 (≥ +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 (≥ 0.75 D) was 9.75%. CONCLUSIONS: 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.

Meeting the need for corrective spectacles in visually impaired Chinese school children: the potential of ready-made spectacles.

PURPOSE: To assess the potential of ready-made (spherical) spectacles (RMS) in meeting the need for refractive correction in visually impaired children in China. METHODS: 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. CONCLUSIONS: 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.

Causes of Visual Impairment and Blindness in the 2006 and 2014 Nine-Province Surveys in Rural China.

PURPOSE: To investigate the primary causes of visual impairment and blindness in rural China. DESIGN: Population-based, cross-sectional study. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Cataract Surgical Coverage and Visual Acuity Outcomes in Rural China in 2014 and Comparisons With the 2006 China Nine-Province Survey.

PURPOSE: To estimate surgical coverage of cataract-related vision impairment and blindness and visual acuity outcomes in operated eyes in rural China in 2014 with comparisons with the 2006 Nine-Province Survey. DESIGN: Population-based, cross-sectional study. METHODS: 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 ocular examination. Surgical coverage and visual acuity outcomes in 2014 were compared with data from the 2006 survey. RESULTS: Among 51 310 examined persons, surgical coverage among those presenting with cataract-related severe visual impairment or blindness (<20/200) was 62.7% overall, ranging from 43.4% to 83.6% across the 9 study sites. Unoperated cataract was significantly associated with older age, female sex, and lack of education. Presenting visual acuity outcomes ≥ 20/63 in cataract-operated eyes was 62.2% overall, ranging from 51.6% to 78.6%, and 75.2%, ranging from 67.1% to 81.5%, with best-corrected visual acuity. As a proportional percentage of cataract surgical coverage in 2006, overall surgical coverage increased by 81.4% during the 2006-2014 interval, and by 110% when adjusted for visual acuity outcomes ≥ 20/63. CONCLUSIONS: Cataract blindness control is well underway in rural China, as evidenced by significant increases in cataract surgical coverage and improvement in visual acuity outcomes during the 2006-2014 interval. Further efforts are needed to provide greater access to affordable cataract surgery for the elderly, female persons, and those with little or no education.

Prevalence of Vision Impairment in Older Adults in Rural China in 2014 and Comparisons With the 2006 China Nine-Province Survey.

PURPOSE: 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. DESIGN: Population-based, cross-sectional study. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Progression of Near Vision Loss and Incidence of Near Vision Impairment in an Adult Chinese Population.

PURPOSE: 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. DESIGN: Population-based, prospective cohort study. PARTICIPANTS: People aged ≥35 years examined at baseline in the Yuexiu District of Guangzhou, China. METHODS: 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). MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.

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

PURPOSE: 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). DESIGN: Population-based, cross-sectional study. PARTICIPANTS: 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. METHODS: 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. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.

Uptake, Barriers and Outcomes in the Follow-up of Patients Referred for Free-of-Cost Cataract Surgery in the Sao Paulo Eye Study.

PURPOSE: To determine uptake, barriers and outcomes in the follow-up of patients referred for free-of-charge, expedited cataract surgery in the Sao Paulo Eye Study (SPES). METHODS: SPES was a population-based study of urban, low-middle income residents aged ≥50 years. Presenting visual acuity (PVA), best-corrected visual acuity, refraction, and slit-lamp examination were performed in 3677 participants. For subjects with cataract as a principal cause of best-corrected visual acuity ≤20/40, surgery was offered free of charge. Two years after the baseline study, surgery uptake, barriers to surgery, and visual outcomes were analyzed. RESULTS: Among 210 (5.71%) participants who had a cataract surgery indication at baseline, 164 (78.1%) were successfully contacted and 55 (33.5%) reported being operated on for cataract, with 51 agreeing to be re-examined. In a multiple logistic regression model, age, sex, schooling, previous cataract surgery, and PVA at baseline were not significantly associated with surgery uptake. Co-existing health conditions (20.4%), fear of surgery (12.2%) and fear of losing eyesight (11.6%) were the most frequent barriers to cataract surgery adherence. Among the 69 eyes operated on in the interval between baseline and follow-up, PVA ≥20/63 was observed in 50 (72.6%, 95% confidence interval, CI, 62.2-82.3%), PVA <20/63-20/200 in 11 (15.8%, 95% CI 8.9-22.9%) and PVA <20/200 in 8 (11.6%, 95% CI 5.3-17.9%). CONCLUSIONS: Quality of surgery is an increasing determinant of uptake rates. Although free-of-charge and expedited cataract surgery was offered, surgical outcomes might have influenced the low uptake. Aside from cataract surgery campaigns, improvement of surgeon skills, accurate biometry, treatment of ocular comorbidities, postoperative follow-up and eye-care education are needed.

[Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Shuangcheng City of Heilongjiang Province: the China Nine-Province Survey].

OBJECTIVE: To investigate the prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Shuangcheng City of Heilongjiang Province, China. METHODS: It was a population-based cross-section study. Geographically defined cluster sampling was used in randomly selecting 5 841 individuals aged 50 years or above in 28 basic sample units in Shuangcheng City from September to December 2006. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination. Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands four hundreds and eighty-one individuals were enumerated and 5 047 persons were examined, the response rate was 92.08%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 1.72% (87/5 047) and 4.69% (237/5 047) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.90% (96/5 047) and 7.23% (365/5 047) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2)=674.44, P < 0.01), female (χ(2)=39.61, P < 0.01) and illiterate (trend χ(2)=142.82, P < 0.01) persons. Cataract (52.70%) was still the first leading cause of blindness and visual impairment. The percentage of the retinal diseases, including age-related macular degeneration, high myopic retinopathy and diabetic retinopathy was 11.31% among the eyes with blindness and moderate and severe visual impairment. Un-corrected refractive error(13.38%) also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment in Shuangcheng City is relatively higher in China Nine Province Survey. Cataract, retinal diseases and un-corrected refractive error are the main causes of the blindness and moderate and severe visual impairment.

[Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Yangxi County of Guangdong Province: the China Nine-Province Survey].

OBJECTIVE: To investigate the prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Yangxi County of Guangdong Province, China. METHODS: It was a population-based cross-section study.Geographically defined cluster sampling was used in randomly selecting 5 531 individuals aged 50 years or above in Yangxi County from September 2006 to January 2007. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated using village registers followed by door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands five hundreds and thirty-one individuals were enumerated and 4 589 persons were examined, the response rate was 82.97%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 2.38% (109/4 589) and 9.44% (433/4 589) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 2.68% (123/4 589) and 18.15% (833/4 589) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 1 239.34, P < 0.01) , female (χ(2) = 37.88, P < 0.01) and illiterate (trend χ(2) = 235.11, P < 0.01) persons. Cataract was the first leading cause of blindness and visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is higher among older adults aged 50 years or above in Yangxi County. Cataract remains as the first leading cause of blindness and visual impairment.

Age-related prevalence and met need for correctable and uncorrectable near vision impairment in a multi-country study.

PURPOSE: To estimate the prevalence, potential determinants, and proportion of met need for near vision impairment (NVI) correctable with refraction approximately 2 years after initial examination of a multi-country cohort. DESIGN: Population-based, prospective cohort study. PARTICIPANTS: People aged ≥35 years examined at baseline in semi-rural (Shunyi) and urban (Guangzhou) sites in China; rural sites in Nepal (Kaski), India (Madurai), and Niger (Dosso); a semi-urban site (Durban) in South Africa; and an urban site (Los Angeles) in the United States. METHODS: Near visual acuity (NVA) with and without current near correction was measured at 40 cm using a logarithm of the minimum angle of resolution near vision tumbling E chart. Participants with uncorrected binocular NVA ≤20/40 were tested with plus sphere lenses to obtain best-corrected binocular NVA. MAIN OUTCOME MEASURES: Prevalence of total NVI (defined as uncorrected NVA ≤20/40) and NVI correctable and uncorrectable to >20/40, and current spectacle wearing among those with bilateral NVA ≤20/63 improving to >20/40 with near correction (met need). RESULTS: Among 13 671 baseline participants, 10 533 (77.2%) attended the follow-up examination. The prevalence of correctable NVI increased with age from 35 to 50-60 years and then decreased at all sites. Multiple logistic regression modeling suggested that correctable NVI was not associated with gender at any site, whereas more educated persons aged >54 years were associated with a higher prevalence of correctable NVI in Nepal and India. Although near vision spectacles were provided free at baseline, wear among those who could benefit was <40% at all but 2 centers (Guangzhou and Los Angeles). CONCLUSIONS: Prevalence of correctable NVI is greatest among persons of working age, and rates of correction are low in many settings, suggesting that strategies targeting the workplace may be needed.

[Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Yongchuan District of Chongqing City: the China Nine-Province survey].

OBJECTIVE: To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Yongchuan of Chongqing City, China. METHODS: It was a population-based cross-section study.Geographically defined cluster sampling was used in randomly selecting 5663 individuals aged ≥ 50 years in Yongchuan District. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands six hundreds and sixty-three individuals were enumerated and 5390 persons were examined, the response rate was 95.18%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 2.12% (114/5390) and 5.40% (291/5390) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 2.49% (134/5390) and 10.71% (577/5390) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 951.32, P = 0.000) , female (χ(2) = 33.35, P = 0.000) and illiterate (trend χ(2) equals; 141.32, P = 0.000) persons. Cataract was still the first leading cause of blindness and visual impairment.Un-corrected refractive error also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is relatively higher among older adults aged 50 years or above in Yongchuan District. The first leading cause of blindness and visual impairment is still cataract.

[Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Longyao County of Hebei Province:the China Nine-Province survey].

OBJECTIVE: To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged ≥ 50 years in Longyao County, Hebei Province, China. METHODS: It was a population-based cross-section study.Geographically defined cluster sampling was used in randomly selecting 5527 individuals aged ≥ 50 years in Longyao County. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands five hundreds and twenty-seven individuals were enumerated and 5051 persons were examined, the response rate was 91.39%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 1.05% (53/5051) and 3.46% (175/5051) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.48% (75/5051) and 7.94% (401/5051) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 897.27, P = 0.000) , female (χ(2) = 30.32, P = 0.000), illiterate (trend χ(2) = 83.20, P = 0.000) persons. Cataract was still the first leading cause of blindness. Un-corrected refractive error also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is relatively lower among China Nine Province Survey. The first leading cause of blindness and visual impairment is still cataract.

[Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Changji City of Xinjiang Uygur Autonomous Region: the China Nine-Province survey].

OBJECTIVE: To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged ≥ 50 years in Changji City of Xinjiang Uygur Autonomous Region, China. METHODS: It was a population-based cross-section study.Geographically defined cluster sampling was used in randomly selecting 5714 individuals aged ≥ 50 years in Changji City. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to received visual acuity measurement and eye examination. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands seven hundreds and fourteen individuals were enumerated and 5250 persons were examined, the response rate was 91.88%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 0.74% (39/5250) and 3.83% (201/5250) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.33% (70/5250) and 8.02% (421/5250) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 617.06, P = 0.000) , illiterate (trend χ(2) = 222.35, P = 0.000) persons. Cataract and was the first leading cause of blindness and visual impairment, the retinal diseases, including age-related macular degeneration, high myopic retinopathy, and diabetic retinopathy, were the second cause of blindness and visual impairment.Un-corrected refractive error was also the important cause of the visual blindness. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is not high among older adults aged ≥ 50 years in Changji City. The first main causes of blindness and visual impairment includes cataract, retinal diseases and un-corrected refractive error.

[Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Luxi County of Yunnan Province: the China Nine-Province survey].

OBJECTIVE: To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged ≥ 50 years in Luxi County of Yunnan Province, China. METHODS: It was a population-based cross-section study. Geographically defined cluster sampling was used in randomly selecting 5575 individuals aged ≥ 50 years in Luxi County. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands five hundreds and seventy-five individuals were enumerated and 5151 persons were examined, the response rate was 92.39%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 4.95% (255/5151) and 9.51% (490/5151) , respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 5.40% (278/5151) and 15.84% (816/5151) , respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (χ(2) = 1349.21, P = 0.000) , illiterate (χ(2) = 203.55, P = 0.000) persons. Cataract was still the first leading cause of blindness and visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is highest in China Nine-Province Survey among older adults aged ≥ 50 years in Luxi County. The first leading cause of blindness and visual impairment is still cataract.

[Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Ji'an county of Jiangxi province:the China Nine-Province Survey].

OBJECTIVE: To investigate the prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Ji'an county of Jiangxi province, China. METHODS: It was a population-based cross-section study. Geographically defined cluster sampling was used in 5402 randomly selected individuals aged ≥ 50 years in 28 clusters in Ji'an from September to November 2006. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits. Eligible individuals were invited to receive visual acuity measurement and eye examination. Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands four hundreds and two individuals were enumerated and 5010 persons were examined, the response rate was 92.74%. Based on the criteria of World Health Organization visual impairment classification in 1973, 78 persons were diagnosed as blindness, 265 persons were diagnosed as moderate and severe visual impairment defined as best corrected visual acuity, the prevalence of blindness and moderate and severe visual impairment were 1.56% and 5.29% respectively. Ninety-four persons were diagnosed as blindness, 726 persons were diagnosed as moderate and severe visual impairment defined as presenting visual acuity, the prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.88% and 14.50% respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 970.15, P = 0.000), female (χ(2) = 89.81, P = 0.000), and illiterate persons (trend χ(2) = 241.85, P = 0.000). Cataract was still the first leading cause of blindness and visual impairment, the retinal diseases was the second. Un-corrected refractive error also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment was higher than other district in China. The first leading cause of blindness and visual impairment is still cataract.

[Prevalence of blindness and low vision among adults aged 50 years or above in Ji'an county of Jiangxi province: the China nine-province survey].

OBJECTIVE: To estimate the prevalence of cataract, the outcomes of cataract surgery, cataract surgical coverage rate, cataract blindness social burden rate in Ji'an county of Jiangxi province, China. METHODS: Cluster sampling was used in randomly selected 5010 individuals aged ≥ 50 years in Ji'an county of Jiangxi province. All individuals were received visual acuity and eye examination, including the evaluation of lens status and cataract surgical status by slit lamp biomicroscopy. Data bank was established by Epi-info Software. Statistical analyses were performed using Stata/SE Statistical Software, release 9.0 (Stata Corp, College Station, TX). Confidence intervals and P values (considered significance at the P < 0.05 level) for prevalence of cataract, cataract surgical coverage rate, cataract blindness social burden rate and outcomes of surgery were calculated with adjustment for clustering effects and stratification associated with the sampling design. RESULTS: In 5010 individuals, 1158 cases of cataract were found, the prevalence of cataract was 23.11% among adults aged 50 or above. The prevalence of cataract was higher in the aged, female (P < 0.01). In 99 eyes with cataract surgery, 50.51% and 5.05% of eyes were performed by the modern extra-capsular surgery and phacoemulsification respectively. The rate of intraocular lens implantation was 55.56%. Post-operative presenting and best corrected visual acuity equal to or more than 0.7 was 10.1% and 45.5% of operated eyes respectively. The main causes of the post-operated eyes with worse visual acuity were post-capsular opacity and refractive error. The cataract surgical coverage rate was 32.29%, and the cataract blindness social burden rate was 3.83%. The cataract surgical rate was lower and cataract blindness social burden rate was higher in the aged persons (P < 0.01). CONCLUSIONS: Cataract is the most common eye disease that may lead into blindness and severe visual impairment among older adults aged equal or more than 50 years. The cataract surgical coverage rate is not high but the cataract blindness social burden rate is heavy in Ji'an county. The rate of intraocular lens implantation need increase and the visual outcomes of the surgery should be further improved in the future.

[Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in the Shunyi District of Beijing: the China Nine-Province Survey].

UNLABELLED: OBJECTIVE To assess the prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in the Shunyi district of Beijing,China. METHODS: It was a population-based cross-section study. Geographically defined cluster sampling was used in 5840 randomly selected individuals aged > or = 50 years in 28 clusters in the Shunyi district from April to August 2006. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits. Eligible individuals were invited to receive visual acuity measurement and eye examination. Statistical analyses were performed using Stata/SE Statistical Software, release 9. 0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands eight hundreds and forty individuals were recruited and 5118 persons were examined,the response rate was 87.64%. Based on the criteria of World Health Organization visual impairment classification in 1973,57 persons were diagnosed as blindness, 160 persons were diagnosed as moderate and severe visual impairment defined as best corrected visual acuity, the prevalence of blindness and moderate and severe visual impairment were 1.11% and 3.12% respectively. Sixty-five persons were diagnosed as blindness, 428 persons were diagnosed as moderate and severe visual impairment defined as presenting visual acuity, the prevalence of blindness and moderate and severe visual impairment were 1.27% and 8. 36% respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend Chi2 = 784.23, P = 0.000), female (Chi2 = 28.35, P = 0.000), and illiterate persons (trend Chi2 = 397.13, P = 0.000). Cataract was still the first leading cause of blindness and visual impairment, the retinal diseases was the second. Un-corrected refractive error also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment has been decreasing among older adults aged 50 years or above in the Shunyi district since 1996. The first leading cause of blindness and visual impairment is still cataract.

[Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Qidong City of Jiangsu Province: the China Nine-Province Survey].

OBJECTIVE: To estimate the prevalence of blindness and low vision among older adults aged > or = 50 years in Qidong City of Jiangsu Province, China, in 2006. METHODS: Cluster sampling was used in randomly selecting 5662 individuals aged > or = 50 years from September to December 2006 in 16 clusters in Qidong City. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits. Eligible individuals were invited to receive visual acuity measurement and eye examination. Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands six hundreds and sixty-two individuals were recruited, the response rate was 90.80%. Based on the criteria of World Health Organization visual impairment classification in 1973,91 persons were diagnosed as blindness, 175 persons were diagnosed as moderate and severe visual impairment defined as best corrected visual acuity, the prevalence of blindness and moderate and severe visual impairment were 1.77% and 3.40% respectively. One hundred and thirteen persons were diagnosed as blindness, 354 persons were diagnosed as moderate and severe visual impairment defined as presenting visual acuity, the prevalence of blindness and moderate and severe visual impairment were 2.20% and 6.89% respectively. The prevalence of blindness and moderate and sever visual impairment was higher in aged (trend Chi2 = 825.16, P = 0.000), female (Chi2 = 19.85, P = 0.001), and illiterate persons (trend Chi2 = 329. 85, P = 0.000). The leading cause of blindness was cataract. CONCLUSIONS: Blindness and low vision are associated with older age and illiterates in Qidong City. According to presenting visual acuity, the causes leading to blindness and low vision are, in descending order, cataract, ocular fundus disease, refractive error and cornea disease.