Pterygium in Tibetans: a population-based study in China


Dr Xiaoming Chen, Ophthalmology Department, West China Hospital, Sichuan University, Chengdu, Sichuan Province 610041, China. E-mail:


Purpose:  To describe the prevalence and to identify associated risk factors for pterygium in a Tibetan population at high altitude in Zeku County, China.

Methods:  A prospective population-based survey was conducted from October to December 2006. A stratified, clustered, randomized sampling procedure was used to select 2632 Tibetan people aged 40 years and older. Pterygium was diagnosed and graded clinically as grade 1 (transparent), 2 (intermediate) and 3 (opaque). Risks factors associated with pterygium were evaluated with logistic regression models.

Results:  From a total of 2632 eligible subjects, 2229 (84.69%) were examined. There were 323 people with pterygium, equivalent to an overall prevalence of 14.49% (95% confidence interval [CI] 13.03–15.95). Pterygium was independently associated with increasing age for persons aged 70–79 years, compared with those aged 40–49 years (odds ratio [OR] 2.0; 95% CI 1.4–2.8), female gender (OR 1.6; 95% CI 1.2–2.0), dry eye symptoms (OR 1.3; 95% CI 1.0–1.7), seldom use of sunglasses/crystal spectacles (OR 4.6; 95% CI 1.9–11.3) or hats (OR 3.6: 95% CI 2.4–5.4), lower education level (<3 years) (OR 1.6; 95% CI 1.1–2.4) and low socioeconomic status (OR 1.9; 95% CI 1.5–2.4).

Conclusions:  The prevalence of pterygium in a Tibetan population at high altitude is significantly high, particularly in certain at-risk groups. The primary causative factors are related to ocular sun exposure, which are easily preventable. Public health schemes to address this serious health issue are urgently needed.