Altitude, altitude, altitude. This is why when I get a phone call from an area code in Colorado or New Mexico, I know what I'm going to hear before the conversation starts.
Dry eye syndrome in elderly Tibetans at high altitude: a population-based study in China.
Lu P, Chen X, Liu X, Yu L, Kang Y, Xie Q, Ke L, Wei X.
Cornea. 2008 Jun;27(5):545-51.
PURPOSE: To determine the prevalence of dry eye syndrome, analyze the relationship between dry eye symptoms and signs, and identify associated risk factors for dry eye syndrome in an elderly Tibetan population at high altitude.
METHODS: A population-based survey was conducted from October 2006 to December 2006. A stratified, clustered, random sampling procedure was used to select 2632 native Tibetan people > or = 40 years of age. Symptoms of dry eye were assessed by using a 6-item validated questionnaire. Dry eye syndrome was diagnosed in those subjects having 1 or more symptoms often or all the time. Positive signs included a tear film breakup time of < or = 10 seconds in 1 or both eyes, a Schirmer test score of < or = 5 mm, or a fluorescein score of > or = 1. Correlations between symptoms and signs were analyzed.
RESULTS: Of a total of 2632 eligible subjects, 2229 (84.69%) were examined. The data of 1840 participants were analyzed. Of 1840 participants, 52.4% (95% confidence interval: 50.2-54.7) were symptomatic. The tear film breakup time of < or = 10 seconds was seen in 35.3% (95% confidence interval: 33.1-37.5), a Schirmer test score of < or = 5 mm was seen in 24.7% (95% confidence interval: 22.8-26.7), and a fluorescein score of > or = 1 was seen in 5.8% (95% confidence interval: 4.7-6.9). The correlations between dry eye symptoms and signs were statistically significant. Independent risk factors for dry eye syndrome were positive dry eye signs, increased age, low education level and socioeconomic status, and higher altitude.
CONCLUSIONS: This study shows a high prevalence rate of dry eye syndrome in elderly Tibetans, representing an important health problem.