Pterygium (conjunctiva), Pterygium
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A pterygium (: ''pterygia'' or ''pterygiums'') is any wing-like triangular membrane occurring in the neck, eyes, knees, elbows, ankles or digits. The term comes from the
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
word ''pterygion'' meaning "wing".


Types

*
Popliteal pterygium syndrome Popliteal pterygium syndrome (PPS) is a rare inherited genetic disorder characterized by distinctive craniofacial, musculoskeletal and genitorourinary symptoms. It is primarily caused by a mutation to the ''IRF6'' gene and follows an autosomal dom ...
, a
congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...
condition affecting the face, limbs, or
genitalia A sex organ, also known as a reproductive organ, is a part of an organism that is involved in sexual reproduction. Sex organs constitute the primary sex characteristics of an organism. Sex organs are responsible for producing and transporting ...
but named after the wing-like structural anomaly behind the knee. * Pterygium (eye) or surfer's eye, a growth on the
cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...
of the
eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...
. * Pterygium colli or
webbed neck A webbed neck, or pterygium colli, is a congenital skin fold that runs along the sides of the neck down to the shoulders. There are many variants. Signs and symptoms On babies, webbed neck may look like loose folds of skin on the neck. As the ch ...
, a congenital skin fold of the neck down to the shoulders. * Pterygium inversum unguis or ventral pterygium, adherence of the
distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...
portion of the nailbed to the ventral surface of the nail plate. * Pterygium unguis or
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
pterygium, scarring between the proximal nail fold and matrix.


Pterygium of the eye

A pterygium reduces
vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...
in several ways: # Distortion of the corneal optics. This begins usually when the pterygium is greater than 2mm from the
corneal limbus The corneal limbus (''Latin'': corneal border) is a highly vascularized and pigmented zone between the cornea, conjunctiva, and the sclera (the white of the eye) that protects and heals the cornea. The cornea is composed of three primary cell ty ...
. # Disruption of the tear. The tear film is the first lens in the eye. Pterygia are associated with eyelid inflammation, called
blepharitis Blepharitis, sometimes known as granulated eyelids, is one of the most common ocular conditions characterized by inflammation, scaling, reddening, and crusting of the eyelid. This condition may also cause swelling, burning, itching, or a grainy ...
. # Growth over the corneal centre, which leads to dramatic reduction of vision. # Induced anterior corneal scarring, which often remains after surgical removal. A pterygium of the eye grows very slowly. Usually it takes several years or decades to progress.


Surgical removal

Indications for surgery, in order of decreasing importance: # Growth over the corneal centre. # Reduced vision due to corneal distortion. # Documented growth. # Symptoms of discomfort. # Cosmesis. Surgery is usually performed under
local anaesthetic A local anesthetic (LA) is a medication that causes absence of all sense, sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sen ...
with light sedation as day surgery. The pterygium is stripped carefully off the surface of the eye. If this is all that is done, the pterygium regrows frequently. The technique with the lowest recurrence rate uses an
autotransplantation Autotransplantation is the transplantation of organs, tissues, or even particular proteins from one part of the body to another in the same person ('' auto-'' meaning "self" in Greek). The autologous tissue (also called autogenous, autogenei ...
of
conjunctiva In the anatomy of the eye, the conjunctiva (: conjunctivae) 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 gobl ...
from under the
eyelid An eyelid ( ) is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral ...
. This is placed over the defect remaining from the removed pterygium. The graft can be stitched in place, which is time-consuming, and painful for the patient afterwards. An alternative is the use of tissue adhesive
fibrin glue Fibrin glue (also called fibrin sealant) is a surgical formulation used to create a fibrin clot for hemostasis, cartilage repair surgeries or wound healing. It contains separately packaged human fibrinogen and human thrombin. Medical uses This ...
. A Cochrane review including 14 studies and last updated October 2016, found that using fibrin glue when doing conjunctival autografting was associated with a reduced likelihood of the pterygium recurring compared with sutures. The review found that operations may take less time but fibrin glue may be associated with more complications (for example, rupture, shrinking, inflammation,
granuloma A granuloma is an aggregation of macrophages (along with other cells) that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such sub ...
). A 3-year clinical study on the application of
collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
matrix as excision site grafts showed significantly improved surgery success rates. The mechanism of the collagen matrix graft (commercially available as ologen) works by promoting healthy
cell growth Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a de ...
into the matrix, thus preventing
conjunctiva In the anatomy of the eye, the conjunctiva (: conjunctivae) 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 gobl ...
overgrowth that can cover the iris.


References


Further reading

* * {{refend Membrane biology eo:Pterigio fr:Ptérygion it:Pterigio nl:Pterygium pms:Pterygium pl:Skrzydlik pt:Pterígio zh:翼状胬肉