A pinguecula is a common type of conjunctival stromal degeneration in the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

. It appears as an elevated yellow-white plaque in the bulbar conjunctiva near the limbus. Calcification may also seen occasionally.

Etiology

The exact etiology is unknown, but it may be associated with aging and excessive exposure to

UV light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

Signs and symptoms

It is seen as a yellow-white deposit on the conjunctiva adjacent to the

limbus Limbus (Lat. "edge, boundary") may refer to: * Corneal limbus, the border of the cornea and the sclera (the white of the eye) * Limbus of fossa ovalis, in the heart * Limbus 3 and Limbus 4, two line-ups of a German avant-garde musical group * Li ...

(the junction between the cornea and

sclera The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and som ...

). (It is to be distinguished clinically from a pterygium, which is a wedge shaped area of fibrosis that may grow onto the cornea.) A pinguecula usually does not cause any symptoms. It is most common in tropical climates and there is a direct correlation with UV exposure. Histologically, there is degeneration of the collagen fibers of the conjunctival stroma with thinning of the overlying

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

and occasionally calcification. Actinic exposure of the thin conjunctival tissue is thought to cause fibroblasts to produce more

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

fibers, which are more twisted than normal elastin fibers and may lead to the degradation of the

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

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.

Associated conditions

A pinguecula is one of the differential diagnoses for a

limbal nodule A limbal nodule is any nodular lesion at the limbus (junction of the cornea and sclera) of the eye. The differential diagnosis for a limbal nodule can include: * Pinguecula *Early Pterygium *Foreign body / foreign body granuloma * Phlycten, an ...

. It may have an increased prevalence in Gaucher's disease.

Diagnosis

Diagnosis of pinguecula is usually done by an eye care professional during routine eye examination using slit lamp. Conjunctival biopsy may be advised if malignancy is suspected.

Treatment

Pingueculae may enlarge slowly over time, but it is a benign condition, usually requiring no treatment. Artificial tears may help to relieve discomfort, if it occurs. If cosmesis is a concern, or if there is discomfort in

contact lens Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic ...

use, surgical excision may be done. Occasionally, a pinguecula may become inflamed, a condition called pingueculitis. The cause of pingueculitis is unknown and there are no known infectious agents associated with it. If an inflamed pinguecula is causing discomfort or cosmetic concerns, it may be treated with short course of topical steroid. Laser photocoagulation may also be used to remove pinguecula.

References

External links

{{Eye pathology Disorders of conjunctiva zh:翼状胬肉