Background: According to global estimates by the World Health Organization (WHO), there were 141 million people with visual impairment in 2002 and cataract was then the leading cause of blindness. A national survey of China in 1987 suggested that the prevalence of blindness (as defined by the WHO) was 0.42% for all ages.
Aim: To evaluate the prevalence and causes of visual impairment in people aged 50 and older in Kunming, China.
Methods: A population-based cross-sectional study was conducted using multi-stage cluster sampling (including probability proportional to size, compacted segment and non-compacted segment sampling) to select 46 clusters of 60 individuals, each over 50 years of age. The standardised protocol for rapid assessment of avoidable blindness (RAAB) was used to identify people with visual impairment (VI) and ophthalmic examination was used to determine the main cause of VI. The RAAB software package and STATA 9 software were used to enter and analyse data.
Results: A total of 2,588 people from the sample of 2,760 were examined. Age-and sex-standardised prevalence of blindness (available corrected visual acuity <3/60 in the better eye) was 2.7%. It was 2.3% for severe visual impairment (SVI) and 7.2% for VI. The main causes of blindness were cataract (63.2%), other corneal scarring (14.7%), and glaucoma (7.4%). In total, 84.2% of blindness was avoidable, including cataract, other corneal scarring, uncorrected aphakia, and surgical complications. Cost was the most common barrier to cataract surgery. Cataract surgical coverage (CSC) in persons with best corrected visual acuity <3/60 was 58.9% . Cataract operations had a good outcome (visual acuity ≥6/18) in 43% of operated eyes.
Conclusion: The prevalence of blindness in Kunming is relatively high. The leading cause of blindness, SVI, and VI is still cataract. CSC is quite low and the outcome of cataract surgery is poor in the survey area.
Miriam Cano examines a patient in the ophthalmic ward of the Social Security Institute (IIPS) Central Hospital. PARAGUAY