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.

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

Among the 3700 people, 169 (4.6%) could not be reached, 20 (0.5%) were unable to communicate, and 27 (0.7%) refused. Consequently, 3484 persons (response rate 94.2%) with a mean (±SD) age of 64.4±9.8 years were examined. These included 1397 men (40.1%) with an average age of 65.3 ±9.6 years and 2087 women (59.9%) with an average age of 63.8±9.8 years.

Of the 2145 subjects (95.3%，2145/2250), 327 (15.2%) refused, and 2 (0.1%) were unable to cooperate for examination. Consequently, 1816 subjects (1816/2145, 84.7%) with a mean (±SD) age of 64.4±9.6 years received the conventional ophthalmic examination in the mobile eye clinic (figure 1). These included 686 men (37.8%) with an average age of 65.5±9.4 years and 1130 women (62.2%) with an average age of 63.8±9.6 years.