The CMGs are guidelines on the diagnosis and management of a range of common and rare, but important, eye conditions that present with varying frequency in primary and first contact care.

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Fibrovascular growth progressing from the bulbar conjunctiva to involve the cornea
Possibly a tissue response to irritants rather than a true degeneration
Overall the prevalence of pterygium is 13%, but depending on demographic, environmental and lifestyle factors could vary from 3% to 20%
Multifactorial aetiology, most popularly attributed to chronic exposure to UV light, dust and wind. The human papillomavirus has also been implicated

Predisposing factors

Older age
Male gender (probably related to occupational exposure)
Long term exposure to ultraviolet radiation

  • sunlight (increased prevalence at low latitudes, outdoor work, especially on reflective surfaces e.g. sand, concrete, water, snow)

Dryness, arid climate


Mild irritation (redness, dryness, foreign body sensation)
May be exacerbated by incidents of acute inflammation
Effect on vision

  • result of astigmatism (with the rule)
  • in severe cases, pterygium may extend over visual axis

Cosmetic concern


Usually bilateral; often asymmetrical. More common nasally
Starts with scarring, thickening and distortion of the bulbar conjunctiva
Small grey corneal opacities appear near the limbus
Conjunctiva overgrows these opacities
Slow insidious growth on to cornea (or may become stable)
Destroys Bowman’s membrane and superficial stroma lamellae
Epithelial iron deposit (Stocker’s line) ahead of advancing pterygium
Relatively rich surface vascularisation
Flattening of cornea in horizontal meridian

Differential diagnosis

Pinguecula (no corneal involvement)

  • adhesion of a fold of conjunctiva to a peripheral corneal ulcer, which is fixed only at its apex to the cornea (pterygium is adherent to underlying structures throughout)

Carcinoma in situ of the cornea or conjunctiva (also known as Bowen’s disease and as intraepithelial squamous cell carcinoma)

Management by optometrist

Practitioners should recognise their limitations and where necessary seek further advice or refer the patient elsewhere

Non pharmacological

Advise on UV protection:

  • brimmed hat, sunglasses (ideally wrap-around style for side protection)
  • reduces risk of progression and of becoming inflamed and irritated

(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Measure and draw diagram (photodocument if possible)
Cold compress when inflamed
(GRADE*: Level of evidence=low, Strength of recommendation=strong)


Ocular lubricants for symptomatic relief (drops for use during the day, unmedicated ointment for use at bedtime) NB Patients on long-term medication may develop sensitivity reactions which may be to active ingredients or to preservative systems (see Clinical Management Guideline on Conjunctivitis Medicamentosa). They should be switched to unpreserved preparations.
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Acute inflammation of a pterygium usually responds to a brief course of a ‘non-penetrating’ topical steroid (e.g. fluorometholoneloteprednol) or a topical non-steroidal drug (off-license use)
NB All patients on topical steroid drops or ointment should have their intraocular pressures checked initially, during and at the end of treatment (see Clinical Management Guideline on Steroid Glaucoma)
(GRADE*: Level of evidence=moderate, Strength of recommendation=weak)


Management category

B2: alleviation/palliation; normally no referral
B1: refer to ophthalmologist if pterygium:

  • threatens visual axis
  • induces irregular astigmatism
  • is associated with chronic inflammation
  • is cosmetically unacceptable

Possible management by ophthalmologist

Acute inflammation

  • topical steroids
  • non steroidal anti-inflammatory agents

A variety of surgical techniques, including:

  • surgical excision (bare sclera resection)
  • surgical excision plus conjunctival closure, conjunctival flap closure or conjunctival autografting; or amniotic membrane grafting
  • adjunctive treatment sometimes given; includes:
    • beta irradiation (post-op)
    • topical thiotepa (post-op)
    • mitomycin C (intra- or post-op)

A recent systematic literature review concluded that bare sclera resection was associated with high rates of recurrence. By contrast, conjunctival or limbal autograft was associated with lower rates of recurrence 

Evidence base

*GRADE: Grading of Recommendations Assessment, Development and Evaluation (

Sources of evidence

Clearfield E, Muthappan V, Wang X, Kuo IC. Conjunctival autograft for pterygium. Cochrane Database of Systematic Reviews 2016;2:CD011349

Fonseca EC, Rocha EM, Arruda GV. Comparison among adjuvant treatments for primary pterygium: a network meta-analysis. Br J Ophthalmol. 2018;102(6):748-756

Frucht-Pery J, Siganos CS, Solomon A, Shvartzenberg T, Richard C, Trinquand C. Topical indomethacin solution versus dexamethasone solution for treatment of inflamed pterygium and pinguecula: a prospective randomized clinical study. Am J Ophthalmol. 1999;127(2):148-52

Rezvan F, Khabazkhoob M, Hooshmand E, Yekta A, Saatchi M, Hashemi H. Prevalence and risk factors of pterygium: a systematic review and meta-analysis. Surv Ophthalmol. 2018;63(5):719-735

Viso E, Gude F, Rodríguez-Ares MT. Prevalence of pinguecula and pterygium in a general population in Spain. Eye (Lond). 2011;25(3):350-7

Plain language summary

A pterygium is a triangular thickening of the conjunctiva (the layer of transparent skin on the white of the eye) which extends on to the outer edge of the cornea (the transparent window at the front of the eye). If the cornea is imagined as a clock face, a pterygium normally occurs at the three and nine o’clock positions, more usually on the nasal side. A pterygium may grow over the corneal surface. Because of tissue shrinkage, it can put tension on the cornea, causing astigmatism (loss of spherical curvature) and reducing the sharpness of vision. Patients may complain of irritation of the affected eye and they may be concerned about the cosmetic appearance.

Pterygium is caused by long-standing exposure of the eyes to ultra-violet (UV) light, dust and wind. Because of this, it is commoner near the equator, where UV levels are higher, than in temperate parts of the world.

Having carefully examined the affected eye(s) the optometrist will record the dimensions of the pterygium for future comparison. Artificial tears and lubricating ointment may be enough to control the irritation of the eyes. If the pterygium is inflamed, a short course of steroid eye drops may be prescribed. If the pterygium continues to grow towards the middle of the cornea, threatening the vision of the eye, or if inflammation cannot be controlled, the patient will be referred to the ophthalmologist. Various different surgical techniques are available if the pterygium needs to be removed.

Version 8
Date of search 16.12.19
Date of revision 20.12.19
Date of publication 23.07.21
Date for review 15.12.21
© College of Optometrists

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