Pterygium is said to be a common disease in many countries. The etiology of pterygium has given rise to much discussion; anatomic, neoplastic inflammatory and degenerative theories have been proposed but its geographical incidence makes it almost necessary to assume that environmental irritation must have something to do with its development. It is generally thought that the pterygium is provoked by irritating substances entering the eye. This may be true, but what that substance is remains obscure. It is a condition found chiefly in the sunny, hot, dusty regions of the world ,mostly between the latitudes of 37 degrees north and south of the equator. The incidence a1so varies with the amount of exposure to these climatic conditions. It is thus most common in workers out-of-doors and therefore more among men than women (at least 2 to 1) except in localities where the exposure of the two sexes is equal. Cheju Island is located approximate1y between 33 degrees and 33 degrees 30' north latitudes. The climatic conditions of this island are characterized by sunny, high temperature, high winds and humid areas. We have observed that the inhabitants of the north coast of Cheju Island are frequent1y affected with pterygia. The 112 cases of clinical pterygia among 969 adult out-patients at the eye clinic of Lazarus Hospital in Cheju City from August 1, 1976 to April 30, 1977 were evaluated statistically. The incidence of pterygium evaluated in Lazarus Eye Clinic was remarkably high (11.56%) as compared with other reports.
Adult ; Female ; Human ; Korea ; Male ; Middle Age ; Pterygium/epidemiology*

BACKGROUNDPterygium is a common ophthalmic disease and an important public health problem. It may be affected by many factors such as age, gender, ultraviolet radiation exposure, and time spent outdoors. This study aimed to investigate the prevalence of pterygium and evaluate the risk factors for the development of pterygium in the aged rural population of Beijing.

METHODSThe investigation is a population-based cross-sectional study. Participants from 198 villages of 13 suburban districts, aged 55 - 85 years old, were invited to complete a medical record, and 37 067 individuals were taken external ocular and fundus photos at Beijing ocular disease survey in 2008-2009. The information was uploaded by Internet and diagnosed with stages and grades by ophthalmological specialists. The prevalence, stages and grades of pterygia were observed.

RESULTSOf the 37 067 individuals, 1395 (3.76%) had pterygium. There was a significantly higher prevalence in male (5.13%) than in female (3.17%, P = 0.000). The prevalence rate increased obviously with ages (chi(2) = 7.939, P = 0.019) in rural Beijing. The average prevalence of 5.91% in Daxing and Fangshan districts with low latitude and low precipitation was significantly higher than that in Miyun and Huairou districts with high latitude and deep precipitation (3.17%, P = 0.000). The majority of the pterygia (43.5%) were in active stage and 46.5% pterygia involved pupil area corneas.

CONCLUSIONSThere is a statistically significant association between latitude and precipitation of habitation region and pterygium formation. Solar radiation, especially ultraviolet exposure represents a significant environment hazard to pterygium development.

Age Distribution ; Aged ; China ; epidemiology ; Female ; Humans ; Male ; Middle Aged ; Pterygium ; epidemiology ; Rural Population ; statistics & numerical data