Look uppterygium in Wiktionary, the free dictionary.

Apterygium (pl.:pterygia orpterygiums) is any wing-like triangular membrane occurring in the neck, eyes, knees, elbows, ankles or digits.[1]

The term comes from theGreek wordpterygion meaning "wing".

• Popliteal pterygium syndrome, acongenital condition affecting the face, limbs, orgenitalia but named after the wing-like structural anomaly behind the knee.
• Pterygium (eye) or surfer's eye, a growth on thecornea of theeye.
• Pterygium colli orwebbed neck, a congenital skin fold of the neck down to the shoulders.
• Pterygium inversum unguis or ventral pterygium, adherence of thedistal portion of thenailbed to the ventral surface of the nail plate.
• Pterygium unguis ordorsal pterygium, scarring between the proximal nail fold and matrix.^[2]

A pterygium reducesvision in several ways:

1. Distortion of thecorneal optics. This begins usually when the pterygium is greater than 2mm from thecorneal limbus.
2. Disruption of thetear. The tear film is the first lens in the eye. Pterygia are associated with eyelid inflammation, calledblepharitis.
3. Growth over the corneal centre, which leads to dramatic reduction of vision.
4. 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.

Indications for surgery, in order of decreasing importance:

1. Growth over the corneal centre.
2. Reduced vision due to corneal distortion.
3. Documented growth.
4. Symptoms of discomfort.
5. Cosmesis.

Surgery is usually performed underlocal anaesthetic 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 anautotransplantation ofconjunctiva from under theeyelid. 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 adhesivefibrin glue. ACochrane 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 withsutures.^[3] 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 3-year clinical study on the application ofcollagen matrix as excision site grafts showed significantly improved surgery success rates.^[4]

The mechanism of the collagen matrix graft (commercially available as ologen) works by promoting healthycell growth into the matrix, thus preventingconjunctiva overgrowth that can cover theiris.^[5][6][7]

• Membrane biology

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