A pinguecula is a common type of conjunctival stromal degeneration in the
eye. 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
The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...
adjacent to the
limbus (the junction between the
cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
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
Pterygium (plural ''pterygia'' or ''pterygiums'') refers to any wing-like triangular membrane occurring in the neck, eyes, knees, elbows, ankles or digits.
The term comes from the Greek word ''pterygion'' meaning "wing".
Types
* Popliteal ptery ...
, which is a wedge shaped area of
fibrosis
Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
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
Actinism () is the property of solar radiation that leads to the production of photochemical and photobiological effects. ''Actinism'' is derived from the Ancient Greek ἀκτίς, ἀκτῖνος ("ray, beam"). The word ''actinism'' is found, ...
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. It may have an increased prevalence in
Gaucher's disease
Gaucher's disease or Gaucher disease () (GD) is a genetic disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polyg ...
.
Diagnosis
Diagnosis of pinguecula is usually done by an
eye care professional
An eye care professional (ECP) is an individual who provides a service related to the eyes or vision. It is any healthcare worker involved in eye care, from one with a small amount of post-secondary training to practitioners with a doctoral level ...
during routine
eye examination
An eye examination is a series of tests performed to assess vision and ability to focus on and discern objects. It also includes other tests and examinations pertaining to the eyes. Eye examinations are primarily performed by an optometrist, op ...
using
slit lamp
A slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope. The lamp facilitates an examination of the anterior segm ...
. Conjunctival
biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
may be advised if
malignancy
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
is suspected.
Treatment
Pingueculae may enlarge slowly over time, but it is a benign condition, usually requiring no treatment.
Artificial tears
Artificial tears are lubricating eye drops used to relieve dryness and irritation of the ocular surface.
Dry eye syndrome ( keratoconjunctivitis sicca) is a common ocular surface disorder and is characterized by disruption of the tear film and i ...
may help to relieve discomfort, if it occurs.
If
cosmesis Cosmesis is the preservation, restoration, or bestowing of bodily beauty.''Dorland's Medical Dictionary''. 25th ed. Philadelphia: W.B. Saunders Co.; 1995 In the medical context, it usually refers to the surgical correction of a disfiguring defect, o ...
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 Topical steroids are the topical forms of corticosteroids. Topical steroids are the most commonly prescribed topical medications for the treatment of rash, eczema, and dermatitis. Topical steroids have anti-inflammatory properties and are classifie ...
.
Laser photocoagulation
Laser coagulation or laser photocoagulation surgery is used to treat a number of eye diseases and has become widely used in recent decades. During the procedure, a laser is used to finely cauterize ocular blood vessels to attempt to bring about var ...
may also be used to remove pinguecula.
See also
*
Peripheral light focusing
Peripheral Light Focusing (PLF) can be described as the focusing of Solar Ultraviolet Radiation (SUVR) at the nasal limbus of the cornea. SUVR incident at the temporal limbus passes across the corneal dome and focuses at the nasal limbus. The limb ...
*
Pterygium (conjunctiva)
A pterygium of the eye (plural ''pterygia'' or ''pterygiums'', also called surfer's eye) is a pinkish, roughly triangular tissue growth of the conjunctiva onto the cornea of the eye. It typically starts on the cornea near the nose. It may slow ...
References
External links
{{Eye pathology
Disorders of conjunctiva
zh:翼状胬肉