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A pinguecula is a common type of conjunctival degeneration in the eye. ==Presentation== It is seen as a yellow- white deposit on the conjunctiva adjacent to the limbus (the junction between the cornea and sclera). It is to be distinguished clinically from pterygium, which is a wedge shaped area of fibrosis that appears to grow into the cornea. It usually does not cause any symptoms. It is most prevalent in tropical climates and is in direct correlation with UV exposure. Histologically it shows degeneration of the collagen fibers of the conjunctiva stroma with thinning of the overlying epithelium and occasional calcification. Solar actinic exposure of the thin conjunctiva tissue results in fibroblasts producing more elastin fibers, but they are more twisted than normal and may lead to the degradation of the collagen fibers. Alternatively, it has been stated that the sub-epithelial collagen fibers undergo degradation and assume the qualities of elastic tissue while fragmenting and twisting in a different configuration from their normal state. It is likely that the solid white scleral tissue underlying the conjunctiva tissue acts with high reflectivity to further back expose the tissue to UV radiation.〔http://www.drkisling.com/2010/06/26/eye-growth-bumps-often-pinguecula/〕 The side of the nose also increases sun reflectivity onto the conjunctiva. As a result, pingueculae are found more often on the nasal side of the conjunctiva. While most pingueculae are found over the age of 40, they are not uncommon in 20 and 30 years old adults who spend significant time in the sun. Pingueculae have abnormal tear surfacing over their surface. The tear ferning test shows abnormalities of the mucous component of the tear film. The tear ferning test has a high predictive value of hydrophilic soft contact lens success. Contact lens intolerance can also result from the elevation of the peripheral edge of the contact lens if it positions on top of the pinguecula. The plural form of ''pinguecula'' is ''pingueculae''. ''Pinguecula'' is derived from the Latin word "pinguis" for fat or grease.〔http://www.wordinfo.info/words/index/info/view_unit/4312/〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pinguecula」の詳細全文を読む スポンサード リンク
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