Prevalence of Blindness, Visual Impairment in Chao Nan Area, China

Study Overview
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Brief Summary
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This study will provide a profile of blindness/visual impairment, avoidable blindness and cataract surgery service in Chaonan, mainland China. We also evaluate the diagnostic accuracy of Rapid Assessment of Avoidable Blindness (RAAB) comparison with conventional survey.

Detailed Description
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This proposal describes a population-based study aimed at determining the prevalence of visual impairment, blindness and major causes in adults age 50 years old and above in Chaonan County of Guangdong province, where one of the Project Vision Charity Eye center was founded in 2009. In the proposed study, we will examine 3700 Chaonan County residents aged 50 years and older, selected via a clustered, randomized sampling with probability proportional to size (PPS). The cluster will be at the village level, 50 subjects aged 50 years and older will be examined in each cluster includes Visual acuity, torch light, and fundus review, the major cause of blindness or visual impairment will be determined. We also randomly recruited 60% clusters,total 2250 participants, from RAAB survey to conduct a detailed conventional eye examination. This study will provide a profile of blindness/visual impairment, avoidable blindness and cataract surgery service in Chaonan. we will evaluate the diagnostic accuracy of Rapid Assessment of Avoidable Blindness (RAAB) comparison with conventional survey. . It will provide important public health issues for the purposes of establishing a sustainable and suitable model to eliminate the cataract blindness in China.

Official Title
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Prevalence of Blindness, Visual Impairment and Main Avoidable Causes in Chao Nan Area

Conditions
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Blindness, Cataract, Visual Impairment, Refractive Errors

Intervention / Treatment
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* Diagnostic Test: Conventional survey


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: aged 50 years and above In each household all persons , residing in the household for six months or more over the past year Residing in the household is defined as sharing meals from the same kitchen with the other members of the household for at least 6 months in a year. Exclude any visitors. Exclusion Criteria: age <50 years old Visitors in the villages Residing in the household< 6 months

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| RAAB survey<br>We will examine 3700 Chaonan County residents aged 50 years and older, selected via a clustered, randomized sampling with probability proportional to size (PPS). The cluster will be at the village level, 50 subjects aged 50 years and older will be examined in each cluster includes Visual acuity, torch light, and fundus review, the major cause of blindness or visual impairment will be determined. | Diagnostic Test: Conventional survey<br> <br> |
| conventional survey<br>All the recruited participants underwent ophthalmic examination according to the RAAB protocol and then 60% of them were re-examined with instruments in a mobile eye clinic set up in a village center on the same day. Examination in the mobile clinic included standardized visual acuity (VA) tests using logarithm of the minimum angle resolution charts, refraction, slit-lamp biomicroscopy, and dilated fundal examination with a binocular indirect ophthalmoscope. | Diagnostic Test: Conventional survey<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the prevalence of blindness and visual impairment (VI) and main avoidable causes in Chaonan, China | the prevalence of blindness and visual impairment (VI), and report the avoidable causes, including cataract in Chaonan Region, Guangdong Province, southern China | one year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the diagnostic accuracy of RAAB | To evaluate the diagnostic accuracy of Rapid Assessment of Avoidable Blindness (RAAB) | one year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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blindness, cataract blindness, diagnostic accuracy