Prevalence and Causes of Blindness and Low Vision in Tehran Province, 2005

To determine the prevalence and causes of blindness and low vision in Tehran province in 2005. A population-based cross-sectional study was carried out involving all habitants living in Tehran province in 2005. The study design was according to the World Health Organization recommendation methods and also a pilot study preformed among rural and urban areas of Karaj. It was a multi-stage cluster sampling method, and sample size was calculated due to the distribution of the total population of Tehran derived from the national census and estimated rates of blindness. Information was collected using a questionnaire, including the general information and results of the optometrists’ and ophthalmologists’ diagnoses. Initial information gathering was performed at the rural and urban health centres. The categorization of blindness and low vision was according to the International Classification of Diseases version 10 (ICD 10). Overall, 11975 subjects with the average age of 27.8 years participated (response rate 90.4%). The prevalence rate of bilateral blindness was 1.09% (95%CI= 0.90-1.61). There was a positive significant trend with age (P<0.001) and no significant difference by sex and residential area. The prevalence rate of low vision was 4.04% (95% CI= 3.69-4.39). The prevalence rate of bilateral low vision was increasing by age (P<0.001) and was higher among females (OR=1.42, 95%CI= 1.16-1.74). However, there was no significant difference by residential area. The leading causes of visual impairment were from cataract (33.9%), amblyopia due to refractive error and so on (22.7%), and vitreo-retinal diseases (12.3%). It is estimated that there is about 124165 bilateral blinds and 463431 people with low vision in Tehran province. Compared to other similar countries, the prevalence rates of blindness and low vision is in average in this community. This study recommends similar studies over the country and reinforces the needs of the expansion of health programs on prevention and control of visual impairments and their causes. Furthermore, employing of these findings is necessary for appropriate design of Vision 2020 program in Iran.