Pinguecula
Encyclopedia
A pinguecula is a common type of conjunctival degeneration in the eye
.
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. 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.
. It may have an increased prevalence in Gaucher's disease
.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
.
Presentation
It is seen as a yellow- white deposit on the conjunctivaConjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
adjacent to the limbus (the junction between the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
and sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...
). 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
Elastin
Elastin is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of...
fibers, but they are more twisted than normal and may lead to the degradation of the collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
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. 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.
Prognosis and treatment
They may enlarge slowly but is a benign condition requiring no treatment. Artificial tears are occasionally used if there is discomfort or to reduce minor injection of blood vessels. If cosmesis is a concern surgical excision is sometimes done. Occasionally a pinguecula may become inflamed, a condition referred to as pingueculitis. The cause of pingueculitis is unknown but there are no known infectious agents associated with its manifestation. If an inflamed pinguecula is causing discomfort or cosmetic concerns it may be treated with anti-inflammatory prescriptions.Associated conditions
A pinguecula is one of the differential diagnoses for a limbal noduleLimbal nodule
A limbal nodule is a non-specific term describing any nodular lesion at the limbus of the eye.The differential diagnosis for a limbal nodule can include:*Pinguecula*Early Pterygium...
. It may have an increased prevalence in Gaucher's disease
Gaucher's disease
Gaucher's disease is a genetic disease in which a fatty substance accumulates in cells and certain organs.Gaucher's disease is the most common of the lysosomal storage diseases. It is caused by a hereditary deficiency of the enzyme glucosylceramidase. The enzyme acts on the fatty acid...
.