In China, cataracts are the leading cause of blindness [1–3], and there are currently approximately 2.5 million people with cataracts in China [4]. The only treatment is surgical removal. In recent years, with the promotion of "Vision 2020--the Right to Sight", under the guidance of and with the support of the Chinese Ministry of Health, Disabled Persons' Federation and non-governmental organisations at home and abroad, significant efforts have been made to promote the treatment of cataract blindness. For example, partial subsidies have been provided by the government and free surgeries have been donated by charitable societies. However, not everyone who needs surgical cataract treatment can benefit from subsidies or charity surgery. Therefore, additional measures to improve this situation are urgently needed.

In 2003, the Chinese government introduced a series of new national health insurance reforms, including the New Cooperative Medical Scheme (NCMS) and the Urban Resident Basic Health insurance scheme (URBMI). These two programs, combined with the previously existing Urban Employee Basic Health Insurance (UEBMI) program, aimed to make it easier for individuals to receive medical treatment.

We wanted to know whether the health insurance reforms have benefited cataract surgery. In this study, we retrospectively investigated the cataract surgery data for Chongqing from 2003 to 2008 to determine whether the health insurance reforms have had some effect on the number of cataract surgeries.

Cataracts are by far the most common cause of major vision loss, accounting for approximately half of all global cases of blindness. According to the World Health Organization (WHO), China is estimated to have the largest number of cataract-blind people in the world [5]. During the past three decades, China has experienced explosive economic growth and development, however, China's cataract surgical rate (CSR), which represents the number of cataract operations performed annually per one million of population, is among the lowest in the world and thus lags behind China's astonishing achievement in other areas.

Why is China's CSR so low with such remarkable economic progress? Among the many contributing factors, the major reason for the low CSR is the low availability of basic social services, particularly health insurance services, in rural areas. It is estimated that out of China's 1.3 billion citizens, more than 60% of China's population lives in rural regions [6], but more than 80% of the country's health resources are concentrated in large cities. This disparity is responsible for the immense gap in health insurance availability between rural and urban populations.

Prior to 2003, there was only one primary insurance program for the urban employed: the Urban Employee Basic Medical Insurance (UEBMI) program. In 2003, the Chinese government launched the New Cooperative Medical Scheme (NCMS), aimed to provide health coverage for the nation's entire rural population by 2010. The NCMS has witnessed a rapid expansion in coverage since its inception, beginning in only 310 out of China's 2861 rural counties in 2004 but expanding to 2451 counties by the end of 2007, accounting for 86% of all rural counties in China [7, 8]. However, another population cohort, the 420 million urban residents without formal employment, was completely left out of the state health insurance safety net. Thus, in the second half of 2007, the Chinese government begun to implement the Urban Resident Basic Health Insurance scheme (URBMI), and the government wants to cover all urban residents by 2010. These three health insurance systems benefit all Chinese citizens [9–15].

Our study revealed that the total number of cataract surgeries had increased each year as had the number of patients with health insurance, suggesting that the availability of health insurance had a significant effect on the number of cataract surgeries. The rates of increase of the numbers of surgeries and insured patients in the rural group were much higher than in the urban group, especially in 2007 and 2008. The odds ratios of having health insurance between the urban and rural groups were relatively stable from 2003 to 2006, but it decreased in 2007 and was significantly lower in 2008. This difference may be related to the implementation of the health insurance reforms, as the NCMS was started in 2003 and expanded quickly up to 86% coverage by 2007, but the URBMI was piloted just in the second half of 2008. These changes are in line with Chinese governmental health insurance reform, indicating that health insurance may have some influence on the amount of cataract surgery in Chongqing.

This study has several limitations. First, not only health insurance reform could affect the number of cataract surgeries, many other factors, such as improved surgical outcomes, increased individual disposable income, enhanced life quality pursuiting, etc, could also have some effects on cataract surgery, but in this study, we could not exclude the other factors' role in the promotion of cataract surgery and make the causal association between insurance coverage and cataract surgery. Second, being a hospital-based retrospective study, we could not elucidate the coverage of health insurance among Chongqing people, therefore, we only investigated the correlation between the number of cataract surgeries and the number of patients with health insurance. These limitations should be addressed in future studies using surveys designed to allow us to further tackle the questions concerning health insurance and the outcomes among patients with cataracts in China.

Health insurance appears to be an important factor associated with increased cataract surgery in Chongqing, China. With the implementation of health insurance, the number of Chongqing's cataract surgeries was increased year by year.