[Prevalence of cataract among the population aged 50 years and over at different altitudes in Gansu Province].

Objective: To assess the prevalence and influence factors of cataract at different altitudes in Gansu Province. Methods: A total of 7 560 permanent residents aged 50 years and over in seven regions of Gansu Province (altitude, 900 meters to 3 500 meters) were selected as subjects, including 2 402 males and 5 158 females, with an average age of 62.04 years. The cluster random sampling method was used to conduct the survey at village or township health service centers. The investigation procedure included questionnaire survey, pre-investigation, visual acuity examination, intraocular pressure measurement, slit lamp microscopy and fundus examination. The diagnostic criterion for cataract was typical opacity of the lens or no other eye diseases that led to visual impairment but with visual acuity less than 0.7. The prevalence of cataract was calculated according to factors such as altitude, age and sex. The Chi-square test and two-element unconditional logistic regression were used for statistical analyses. Results: A total of 7 560 people were surveyed. The prevalence rate of cataract was 39.7%, and the age-standardized prevalence was 37.7%. The prevalence of cataract increased with age (χ(2)=2 107.19, P<0.01). It was 14.1% in the group of 50-59 years, 42.9% in the group of 60-69 years and 79.2% in the group of over 70 years. The prevalence of cataract also increased with altitude (χ(2)=33.66, P<0.01). It was 36.9% in the group of altitude less than 1 000 meters, 39.0% in the group of altitude between 1 000 meters and 1 999 meters, 45.9% in the group of altitude between 2 000 meters and 2 999 meters, and 51.5% in the group of altitude more than 3 000 meters. With age stratification, the prevalence of cataract at high altitude was higher than that at low altitude (χ(2)=26.74, 16.06, P<0.01). Multivariate regression analysis showed that the risk of cataract was higher in subjects at altitude of 2 000-2 999 meters than those below 1 000 meters (OR=1.42, 95%CI 1.11-1.82), and even higher in those at altitude of 3 000 meters (OR=1.76, 95%CI 1.01-3.06). Conclusions: High altitude and old age are important risk factors for cataract, and high altitude is an independent risk factor for cataract. It is necessary for local health institutions to take measures to reduce the prevalence of blindness and low vision, especially the blindness caused by cataract. (Chin J Ophthalmol, 2019, 55:589-594).目的： 探讨甘肃省不同海拔地区人群的白内障患病情况及其影响因素。 方法： 调查研究。选取甘肃省7个不同海拔（900~3 500 m）地区的50岁及以上常住居民7 560名作为调查对象，其中男性2 402名，女性5 158名；平均年龄62.04岁。采用整群随机抽样的方法进行调查，调查地点为居民所在的村或者乡镇卫生服务中心。调查程序包括问卷调查、预调查、视力检查、眼压、裂隙灯显微镜检查及眼底检查。白内障诊断标准为典型的晶状体混浊或无其他导致视力下降眼病而视力<0.7。按居住地海拔和年龄、性别等因素分别计算白内障的患病率。统计学方法采用卡方检验、二元非条件logistic回归分析。 结果： 接受此次调查的7 560人中有白内障患者2 999例，患病率为39.7%，年龄标准化患病率为37.7%。不同年龄段之间白内障患病率随年龄增大而升高，差异有统计学意义（χ(2)=2 107.19，P<0.01），其中50~59岁年龄组白内障患病率为14.1%，60~69岁年龄组为42.9%，70岁以上年龄组为79.2%。不同海拔之间白内障患病率随海拔升高而升高，差异有统计学意义（χ(2)=33.66，P<0.01），其中居住地海拔<1 000 m组白内障患病率为36.9%，1 000~1 999 m组为39.0%，2 000~2 999 m组为45.9%，3 000 m以上组为51.5%。按年龄组分层，高海拔地区白内障患病率高于低海拔地区，差异有统计学意义（χ(2)=26.74，16.06；P<0.01）。多因素回归分析显示，海拔2 000~2 999 m较1 000 m以下的受检者患白内障风险高（OR=1.42，95%CI为1.11~1.82），3 000 m以上地区受检者患白内障风险更高（OR=1.76，95%CI为1.01~3.06）。 结论： 高海拔和高龄是导致白内障的重要危险因素，且高海拔是白内障的一个独立的危险因素，需要当地卫生机构采取措施来降低当地盲和低视力患病率，尤其是白内障盲。（中华眼科杂志，2019，55：589-594）.