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

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.

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