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May 1989

Age-Related Cataract in the Tibet Eye Study

Author Affiliations

From Peking Union Medical College Hospital, Beijing, China (Drs Hu and Zhao); People's Hospital of Tibet, Lhasa, China (Dr Zhen); the National Eye Institute, National Institutes of Health, Bethesda, Md (Drs Sperduto and Milton); and Juntendo University Medical School, World Health Organization Collaborating Centre for the Prevention of Blindness, Tokyo (Dr Nakajima). A complete list of participants in the Tibet Eye Study appears at the end of this article.

Arch Ophthalmol. 1989;107(5):666-669. doi:10.1001/archopht.1989.01070010684027

• The Tibet Eye Study was designed to estimate the prevalence of age-related cataract in Duilong-Deqing County, west of Lhasa, China (altitude, 4000 m). Previous reports have suggested an unusually high prevalence of age-related cataract in Tibet. A two-stage probability sample of persons aged 20 years or older from the 35 townships of the county targeted 2884 persons for inclusion in the study; 2665 (92.4%) were examined. Age-related cataract was diagnosed when (1) visual acuity was worse than 6/12 (20/40) because of nuclear or cortical (including posterior subcapsular) opacities, or (2) aphakia associated with a history of age-related cataract was present in either eye. The prevalence of age-related cataract among persons aged 20 to 39 years was 0.2%; among persons 40 years old or older, the prevalence was 11.8%. Cortical cataracts were by far the most common type of cataract diagnosed. Age- and sexadjusted prevalence in Tibet was 60% higher than the prevalence in a similar, previously conducted study of 6951 person in Shunyi County, northeast of Beijing (altitude, 50 m). A second, independent slit-lamp classification of lens status was conducted in the Tibet Eye Study using standard photographs previously described. Age-specific cataract prevalence was similar with the two examination techniques. Results from the Tibet Eye Study support previous suggestions of a high prevalence of age-related cataract in Tibet.

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