Date Published: August 10, 2017
Publisher: Public Library of Science
Author(s): Xiujuan Zhang, Emmy Y. Li, Christopher Kai-Shun Leung, David C. Musch, Xin Tang, Chongren Zheng, Mingguang He, David F. Chang, Dennis Shun-Chiu Lam, James Fielding Hejtmancik.
To estimate the prevalence and causes of blindness and visual impairment (VI), and report the outcomes of cataract surgery in Chaonan Region, Guangdong Province, southern China
Cross-sectional population-based survey
A total of 3484 participants including 1397 men (40.1%) and 2087 women (59.9%) aged ≥50 years were examined (94.2% response rate).
A two-stage cluster sampling procedure was used to select 3700 participants aged ≥50 years from 74 clusters of Chaonan Region. Participants were examined according to the Rapid Assessment of Avoidable Blindness (RAAB) method. Blindness and visual impairment (VI) were defined by the World Health Organization criteria. Participants with visual acuity (VA) < 6/18 in either eye were examined by ophthalmologists. The primary causes of blindness and VI were reported with reference to the participant’s better eye. Prevalence and main causes of blindness, severe visual impairment (SVI), VI and the outcomes of cataract surgery The standardized prevalence rates of blindness, SVI, and VI were 2.4% (95% confidence interval [CI], 1.9–2.9%), 1.0% (95% CI, 0.7–1.4%), and 6.4% (95% CI, 5.6%– 7.1%), respectively. The principal cause of blindness and SVI was cataract, accounting for 67.1% and 67.6% respectively, and the principal cause of VI was refractive error (46.9%). One hundred and fifty five out of 3484 (4.4%) people (211 eyes) had cataract surgery. Of the 211 eyes that had cataract surgery, 96.7% were pseudophakic. 67.2% of the 211 operated eyes had a presenting visual acuity (PVA) of 6/18 or better. The prevalence of blindness, SVI, and VI was high among rural residents in Chaonan. Cataract remained the leading cause of avoidable blindness. Outcomes of cataract surgery performed in rural private clinics were suboptimal. Quality-control initiatives such as hands-on training program should be introduced to improve cataract surgery outcomes.
In 2010, the World Health Organization (WHO) estimated that there were 39 million people in the world with blindness and 285 million with visual impairment. China had the largest number with 8 million blind and 75 million visually impaired individuals. Population based surveys in China have identified cataract as the leading cause of blindness and visual impairment[2–7]. Cataract surgery is an effective means to reverse cataract blindness. However, the cataract surgical rate (CSR) in China remains relatively low at about 772 cases per one million per year, which is much lower than its neighbor India. A major cause of the low CSR is the lack of experienced surgeons in rural areas. The Chinese Ministry of Health has reported that 45% of China’s 2400 county hospitals do not offer cataract surgery services and most rural residents are unable to afford surgery in urban centers. Thus, a large number of patients with severe cataract have little or no access to affordable surgical services. On this account, Project Vision, a non-governmental organization, was established to build a sustainable model to reduce cataract blindness in rural China. Project Vision’s first priority is to develop rural charity eye centers wherein local doctors are trained to provide high quality and low cost cataract surgery.
This study was approved by the Ethics Committee of the Chinese University of Hong Kong and the Disabled Federation of Chaonan Region, and conformed to the tenets of the Declaration of Helsinki. Subjects aged ≥50 years, residing in 11 towns and 241 villages in the Chaonan region were enrolled from April to July in 2012. Persons were considered ineligible if they had moved out of the village, had not lived there in the past 6 months since we selected the sample in April 2012. All the study procedures were explained in detail to each subject and the family by the study investigators with local dialect, in the presence of two to three community heads of the village. Written informed consent with signature or inked fingerprint was obtained from all participants before examination.
The prevalence of blindness varies in different regions of China, ranging from 0.6% (in Gaungzhou City) to 4.4% (in Hainan province)[2–5, 16, 22–24]. The reported prevalence of blindness in Chaonan in 2012(2.4%) was similar to the Nine-Province survey in China (2.3%) in 2008. The prevalence of blindness in Chaonan (2.4%) was much higher than that in Guangzhou City (0.6%), the capital of Guangdong Province. This may be primarily related to lower socioeconomic status, which has been associated with higher prevalence of blindness, among the sample population. Chaonan’s per capita gross domestic product in 2010 was 14,201 RMB (renminbi, Chinese currency unit; approximately USD 2219; 6.4 renminbi = US$1), which was considerably lower than that of Guangdong Province as a whole (43,596 RMB, USD6812) and Guangzhou City (83,494 RMB, USD 13045) in the same year. Similar results were reported in Beijing Eye Study.