Pterygium and pingueculum are variants of the same condition in which the conjunctiva (a membrane that covers the white of the eye) is damaged and responds by continuing to grow. 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 centrally onto the cornea, whereas in a pingueculum the conjunctiva only grows locally on the visible white of the eye. 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
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
CAPTION: A small pterygium underneath a soft contact lens
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 is required.4
CAPTION: A small, reasonably uninflammed pingueculum.
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 J Ophthalmol. 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. 2014 Apr;98(4):423-4.