Pterygium and Pinguecula
Pterygium and pingueculum are common conjunctival lesions, caused by sun exposure. In both conditions, the conjunctiva changes appearance, often becoming inflamed or vascularised. It occurs most commonly in people who spent a great deal of time outdoors.1,2 In the case of a pterygium, the conjunctiva grows from the outside corner of the eye (almost always from the side closer to the nose) onto the cornea in the middle. A pingueculum only grows locally on the visible white of the eye, rather than invading the cornea. The primary complaints about both pterygia and pinguecula are poor cosmetic appearance but they may also cause significant irritation and pterygia can cause reversible vision loss.1 Damage from sun exposure is the main mechanism of both of these conditions.
What is a pterygium?
A pterygium is most commonly found on the nasal side of the cornea and represents a ‘wing’ (ptery is wing in Latin) of degenerated conjunctival tissue.3 A pterygium may be small with minimal symptoms or grow large enough to interfere with vision by obstructing the pupil. It can also distort the cornea, leading to astigmatism which will also interfere with vision. Where the vision is significantly affected, they can be removed with surgery, although there is a risk the pterygium may grow back.3
A pteriguym forms when the corneal limbal cells are damaged, preventing corneal epithelial cells from being produced, in turn causing conjunctival tissue to migrate to protect the cornea.
What is a pingueculum?
Pinguecula are very common, affecting over half of eyes in sunny climates and most often occur in the visible white of the eye, adjacent to the edge of the cornea.1,2 They are often raised areas of abnormal conjunctival tissue that are generally slow to develop. Occasionally they can become inflamed - due to their raised shape they are the first part of the eye to dry out and are prone to frictional forces from the lids. Lubrication and sometimes therapeutic intervention are required.4
A pingueculum forms when the conjunctival tissue is damaged from UV exposure, causing the tissue to thicken, harden and occasionally calcify.
A pingueculum will not turn into a pterygium. Although both caused by sun exposure, they are two separate entities. It is not impossible for an eye with a pingueculum can develop a pterygium, though one cannot transform into the other.
References
Viso E, Gude F, Rodríguez-Ares MT. Prevalence of pinguecula and pterygium in a general population in Spain. Eye (Lond). 2011 Mar;25(3):350-7.
Panchapakesan J, Hourihan F, Mitchell P. Prevalence of pterygium and pinguecula: the Blue Mountains Eye Study. Aust NZ JOphthalmol. 1998 May;26 Suppl 1:S2-5.
Chen J, Maqsood S, Kaye S, Tey A, Ahmad S.Pterygium: are we any closer to the cause? Br J Ophthalmol. 2014Apr;98(4):423-4.
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 Feb;127(2):148-52.
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