Women bear approximately two-thirds of the global burden of blindness, with cataract being the major cause in developing countries (1), and it is likely that much of the excess female blindness in these countries is due to cataract. To examine whether the problem of cataract blindness is being addressed by local services, we reviewed population-based cataract surveys of developing countries, and determined the cataract surgical coverage rate (2, 3) for males and females. This is defined as the number of cataract blind who have been operated divided by the total number of cataract blind (operated plus unoperated people) in the population.
To identify surveys of cataract blindness, we searched several computer databases, including Medline, Embase, Healthstar, Current Contents, LILAC, Scisearch and Biosis. This ensured coverage of journals from Europe, North and South America, and Asia. All databases turned up surveys listed in Medline. To identify, further relevant citations, we reviewed references cited in the retrieved surveys.
All identified articles and surveys were reviewed, using a standard checklist, to select those that met the following criteria: they were methodologically sound population-based prevalence surveys that included (but were not limited to) adults; they had a minimum sample size of 1000 and at least an 80% survey response rate; they were published between 1980 and 1999 and written in English, French, Chinese, Spanish, or Portuguese; and they reported the number of cataract blind and the number having cataract surgery, by sex.
From the eight surveys that met the above criteria, we extracted the cataract surgical coverage rate for males and females. Data were synthesized and analysed using the Cochrane Review Manager software, RevMan 4.0 for Windows. Peto odds ratios and a fixed-effects model were used to combine data across all surveys. For each survey, we also calculated how many additional females would have undergone surgery, and what percentage of current cataract blindness would be alleviated, if females had the same cataract surgical coverage rates as males.
Eight surveys in the literature met the inclusion criteria (Table 1). In addition, we included unpublished population-based data from our 1999 blindness survey of 1500 adults in the Lower Shire Valley, Malawi. One survey in Nepal was unusual in that, although they had population-based data on the number of operated cataracts, they extrapolated from a previous population-based survey to arrive at the current number of cataract blind (4). This survey is included in Table 1, but was not included in the meta-analysis because of its very large size and non-standard methods.
In all of the surveys, cataract surgical coverage rates were lower for females than males. The overall odds ratio for females (compared to males) in the meta-analysis was 0.67 (95% CI: 0.60-0.74). The data also indicate that women accounted for 63% (median) of all cataract cases in these populations, despite their lower coverage. If females had the same cataract surgical coverage as males, the median incidence of cataract blindness would be reduced by 12.5%.
The study findings demonstrate that females do not receive cataract surgery at the same rate as males, and that closing the gender gap could significantly decrease the incidence of cataract blindness. Our findings are limited, in that the data are mostly from a few regions of Asia, with only two African countries and no Latin American countries represented. There are probably many reasons for the gender gap. In general, differences in surgical coverage rates could be attributed to gender-defined social roles, which could be confounded by socioeconomic factors, such as literacy, socioeconomic status and marital status. Documented reasons for low use of services vary by location, and include the following. …