Summer’s blight: pterygia

A pterygium is a common benign ocular surface growth. It typically starts on the nasal conjunctiva close to the limbus as a pinkish, triangular tissue growth and extends across the cornea. The cornea is susceptible to ultraviolet (UV) radiation due to its exposed position at the front of the eye, its shape and its natural transparency, which lead to a peripheral UV-focusing effect on the nasal limbus. There, the UV radiation is amplified by a factor of 20. Chronic UV light exposure is a known cause of degenerative deposition of subepithelial collagen fibres (scar), which eventually leads to pterygium development. Often both eyes are involved. Pterygia are progressive and slowly grow over time, but rarely so large that the pupil is covered.