| Background Pterygium is a common and frequent ocular surface disease. It was defined as a fleshy, triangular encroachment of fibrovascular tissue on the cornea in the interpalpebral fissure. The prevalence of pterygium in different places were various, from 1.2% in urban, temperate white people to 23.4% in the black population of tropical Babados. The disease can result in obvious cosmetic problems, significant astigmatism, and visual impairment or blindness due to interference with visual axis. Numerous theories regarding to the pathogenesis of pterygium included genetic, environmental, infective and immunological factors. Although the hypothesis implicating ultraviolet radiation (UVR) as a risk factor has been well studied in population-based studies, case-control studies and laboratory studies, the definitive cause of pterygium is not well understood. Insights into risk factors, causes, and the distribution of the disease may be useful in guiding appropriate strategies for preventive measures. As with theories of pathogenesis and risk factors, techniques of treatment for pterygium have advanced in recent years. The epidemiologic survey of pterygium has not been sufficiently investigated in rural areas of Shandong province. Therefore, this study was performed to provide informative resources of pterygium in rural residents aged 50 years or above in Shandong Province from April 2008 to July 2008. This study was a part of them.Objective To describe the prevalence and risk factors for pterygium in a population-based sample of individuals aged 50 years and older in rural areas of Juancheng County, Shandong province. Moreover, the connected importance of pterygium was also examined for the intention of offering policy basis and epidemiological data in prevention and therapy of pterygium in large populations.Methods A population-based survey was conduced in Juancheng County, Shandong province. During April to July in 2008, a random cluster sampling was used to choose the local inhabitants in Juancheng County. All eligible adults received a comprehensive examination of the eye and completed a structured questionnaire about associated risk factors for the development of pterygium. Pterygium was diagnosed by ophthalmologists using slit-lamp biomicroscopy. Statistical analysis was performed using SPSS 13.0 for windows χ2-test was used to compare the prevalence of each group.The risk factors of pterygium were compared among different subgroups using univariate Logistic regression analysis. Multivariate logistic regression models were used to determine independent associated risk factors. A prelim test was accomplished before the usual field investing, and repetitive test was also finished to ensure the characteristic of the field investigation. Moreover, before, during and subsequent to the field investing, the relevant quality control was strictly followed for whole investing to assure the plausibility.Results Of the 5287 subjects aged 50 years and above,4866 participants (examination rate 92.04%) underwent the examinations. There were 455 cases of pterygium, the prevalence was 9.4% The pterygium prevalence was 6.9% for the 50 and over crowd,10.4% for the 60 and over crowd,14.5% for the 70 and over crowd,10.8% for the 80 and over crowd, the prevalence of pterygium increase with the age; the difference of prevalence rates among all age groups had statistical significant (P=0.000). The pterygium prevalence was 8.4% for male and 10.1% for female, and there was significant difference between two groups (P=0.044). The prevalence for persons with illiteracy was 9.4%, the prevalence of population who completed primary school was 11.3%, and the prevalence of population who completed junior school or above was 5.7%, the difference of prevalence rates among groups had no statistical significant (P=0.084). The prevalence of population in marriage was 9.0%, and the prevalence of solitary ones was 13.1%, there was significant difference between two groups (P=0.006). The prevalence for persons with an average yearly income below 1000 yuan was 8.9%, the prevalence for persons with an average yearly income above 1000 yuan was 9.3%, the prevalence for persons with an average yearly income above 3000 yuan was 11.9%, the prevalence for persons with an average yearly income above 5000 yuan was 9.8%, there was no significant difference among groups (P=0.688). The prevalence in low-income household was 10.9%, and non low income household was 9.3%, the prevalence in low income household is higher than in non low income household. There was no significant difference between two groups (P=0.690). The prevalence was 11.6% in the group with systemic disease whereas 8.9% in the other group without systemic disease, and there was significant difference between two groups (P=0.021). The prevalence for individuals with diabetes was 3.8%, while 9.4% in the group has no diabetes mellitus, and there was no significant difference between two groups (P=0.092). The prevalence for persons with hypertension was 10.5% whereas 9.1% in the group without hypertension, and there was no significant difference between them (P=0.242). The prevalence for persons with hyperlipidemia was 10.0%, while 9.1% in the group without hyperlipidemia, and there was no significant difference between two groups (P=0.754). The prevalence for persons with cardiac diseases was 12.7%, while 9.2% in group has no cardiac diseases, and there was no significant difference between them (P=0.078). The prevalence for individuals with stroke was 13.4%, while 9.3% in group has no stroke, and there was no significant difference between them (P=0.248). The prevalence for persons with outdoor time equaled or more than four hours per day was 28.8% and was 9.1% in less than 4 hours per day, there was significant difference between two groups (P=0.000). The prevalence of population who wear hat and/or sunglasses when outside was 0.0%, while 10.3% in group without hat and/or sunglasses, and there was significant difference between two groups (P=0.000). The prevalence was 9.3% in group with alcohol taking, while 9.4% in group has no alcohol taking, and there was no significant difference between them (P=0.928). The prevalence was 9.6% in group with smoker, while 9.3% in group has no smoker, and there was no significant difference (P=0.768). The prevalence for persons with high-sodium diet was 11.2%, the prevalence of population with medium sodium diet was 8.8%, and the prevalence for persons with low-sodium diet was 6.5%, the difference of prevalence rates among groups had statistical significant (P=0.013). The prevalence of population who watch TV per day was 15.8%, the prevalence of population who often watch TV was 9.5%, and the prevalence of population who seldom watch TV was 7.5%. The difference of prevalence rates among groups had no statistical significant (P=0.184). The prevalence was 70.0% in group with close-up work per day,9.8% in group with often close-up work, and 6.1% in group with seldom close-up work. The difference of prevalence rates among groups had statistical significant (P=0.000). The self-assessment healthy group was 7.6%, while the abnormal group was 23.8%, and there was significant difference between two groups (P=0.000). The prevalence in visual acuity group based on self-assessment was 6.0%, and was 13.9% in normal group, and there was significant difference (P=0.000). The result of multivariate logistic regression analyses indicated that older age, outdoor time equal or more than four hours per day, close-up work, use of hat and/or sunglasses, the healthy based on self-assessment, the visual acuity based on self-assessment were the main reasons for pterygium formation.Conclusions The prevalence of pterygium was 9.4% in rural people aged 50 years or above in Juancheng County. Older age, outdoor time equal or more than four hours per day, close-up work, the visual acuity based on self-assessment were independently associated with a higher risk for pterygium. There was a slight protective effect between pterygium and the poor healthy based on self-assessment. The public health challenge is to inculcate the use of this protection as routine, proper eye examination, health education, and introduce suitable lifestyle modifications in rural populations in the economic and health of poor. |
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