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K. Sasaki, H. Sasaki, R. Honda, Y. Kawakami, M. Kojima, Y. Sakamoto, J. Qu, Y. Yamashiro, J. Zhang, Z. Liu; High Prevalence of Pterygium in the Population of a Tropical Area in China -Sanya Eye Study-. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5292.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the prevalence of pterygium among rural inhabitants in a tropical area of China.
Some 558 people (79.6% of the total population) aged 50 yrs and over living in Miaolin village in the suburb of Sanya City (latitude 18° N) were enrolled in this survey. Diagnosis of pterygium was determined, by a single observer, as conjunctival tissue covering the surface of the periphery of the cornea. Severity of pterygium was classified into three grades according to the proportion of the radius covered; grade 1 (< 1/3), grade 2 (1/3 to 2/3) and grade 3 (> 2/3). Subjects were excluded from the study if there was another documented explanation for the impairment such as trauma. Cases where surgery for pterygium had been performed were also diagnosed as cases of pterygium. Statistical analysis was done using Fisher’s exact test, Cochran-Armitage trend test and Logistic regression analysis.
Prevalence of pterygium was 71.7% and was significantly higher in females (74.9%) than in males (66.0%). Prevalence increased as eyes aged with 61.6% in their 50s, 80.8% in their 60s, 83.7% in their 70s and 84.4% in those aged 80 yrs and over; a total of 49.9% were bilateral and 20.4% unilateral. Regarding severity, 61.8% were grade 1, 23.3% grade 2 and 14.9% grade 3. Regarding location, 82.7% were nasal, 2.6% temporal and 14.7% both (only in right eyes). Although 96.2% of the subjects usually wore hats, less than 10% of subjects wore glasses or sunglasses when outdoors.
Pterygium was seen in more than 70% of farmers aged over 50yrs living in a tropical area of China. A long time spent outdoors in high ambient UV may have caused this high prevalence. These results show that wearing a hat without glasses does not offer enough protection for eyes from UV. A campaign to enlighten people to the danger of UV and the need to protect their eyes is important.
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