A pinguecula is a common type of conjunctival stromal degeneration in the human eye. It appears as an elevated yellow-white plaque in the bulbar conjunctiva near the limbus. Calcification may also be seen occasionally.
Histologically, there is degeneration of the collagen fibers of the conjunctival stroma with thinning of the overlying epithelium and occasionally calcification. Actinism exposure of the thin conjunctival tissue is thought to cause fibroblasts to produce more elastin fibers, which are more twisted than normal elastin fibers and may lead to the degradation of the collagen fibers. Alternatively, it has been postulated 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 thought that the high reflectivity of the solid white scleral tissue underlying the conjunctival tissue may result in additional UV exposure to the back side of the tissue. The side of the nose also reflects sunlight on to the conjunctiva. As a result, pingueculae tend to occur more often on the nasal side of the eye. While most pingueculae are found in people over the age of 40, they are not uncommon in 20- and 30-year-old adults who spend significant time in the sun.
The surface of the conjunctival tissue overlying a pinguecula interferes with the normal spreading of the tear film. The tear ferning test reveals abnormalities of the mucous component of the tear film, making it useful as a predictor of a person's tolerance of hydrophilic soft contact lenses. Contact lens intolerance can also result from the elevation of the peripheral edge of the contact lens if it overlies a pinguecula.
The plural form of pinguecula is pingueculae. Pinguecula is derived from the Latin word "pinguis" for fat or grease.
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