Objective: To estimate the prevalence of visual impairment among adults aged ≥ 40 years, compare the prevalence between Uyghur and Han residents and analyze the causes of visual impairment.
Methods: Population-based cluster sampling survey was conducted among a target population of 5032 persons ≥ 40 years of age from Shuimogou District in Urumqi, Xinjiang Uyghur Autonomous Region. Distance visual acuity (VA) was measured with a Tumbling-E chart at 5 m. Presenting and best corrected VA were recorded. Clinical evaluations were performed. And primary causes of visual impairment was determined for those with VA < 0.3.
Results: Among them, there were 4104 responders (Uyghur 2006 persons, Han 2098 persons) with a response rate 81.56%. Prevalence of bilateral blindness was 1.25%/1.86% (Uyghur/Han) (P < 0.05) and bilateral low vision 4.04%/3.29% (Uyghur/Han) (P < 0.05). Primary cause of visual impairment among participants was cataract (cause proportion of 49.23% among Uyghurs and 51.85% among Hans). Visual impairment was correlated with advanced age, males and poor literacy. Prevalences of bilateral blindness and bilateral low vision in age group 40 - 50 yr increased from 0.48% and 1.13% to 3.47% and 10.88% in age group ≥ 70 among Uygur citizens respectively (χ(2) = 22.36, P < 0.05 vs χ(2) = 70.97, P < 0.05). Relative data among the Han citizens varied from 0% and 1.42% to 4.39% and 7.89% (χ(2) = 27.94, P < 0.05 vs χ(2) = 39.99, P < 0.05).
Conclusion: The most frequent cause of visual impairment in this area is cataract (Uyghur 49.23% vs Han 51.85%) while retinal diseases and glaucoma are important causes as well. Blindness prevention programs targeting the elderly should be expanded, particularly in areas with a limited access and affordability of eye care services.