Pterygium Surgery Download PDF, 413KB, PDF A pterygium is a wing-shaped, benign growth of conjunctival tissue across the cornea. It usually occurs on the side of the eye and grows very slowly over many years.Risk factors which have been associated with pterygium include ultra-violet radiation from sunlight exposure and chronic eye irritation from dry climate. As the pterygium grows larger, it may blur the vision by causing astigmatism or blocking the visual axis. [Please download the PDF file if you are unable to view the image below.]