A pterygium is a raised, yellowish, wedge-shaped thickening on the white part of the eye. It can occasionally spread to cover part of the cornea and in this case, it will obstruct your vision. It is painless, although it can cause irritation and dryness. Lots of exposure to ultraviolet light (especially from the sun), irritants like dust and wind, and dry eyes are the most probable causes of a pterygium. It is particularly common in those who have lived in hot climates. It is also called ‘surfer’s eye’ or ‘ farmer’s eye’, as it is common in those who spend a lot of time outdoors, where there are high levels of solar radiation. It can be treated by surgery (either for cosmetic reasons or because it is starting to block vision) but it often recurs. Mild cases can be treated with eye drops to ease discomfort, but remember that prevention is the best cure, so always protect your eyes in strong sunlight by wearing good sunglasses.