©2008 Ethis Communications, Inc. The Ocular Surface ISSN: 1542-0124. Murube J. Pterygium: descriptive nomenclature of the past. 2008;6(3):104-107. teryg ion comes from the Greek roots pteron (feather, wing) and pteryx, pterigos (wing, fin, bird). The Greek roots pteron and pteryx have been used in the recent scientific literature to create several neologisms of modern languages, such as pterygoid (bone or object with wing-like form), pterodactyl and pterosaur (extinct reptiles with interdigital membranes, similar to those of the bat), pteropus (flying fox), helicopter (a kind of aircraft kept hovering by helices), hemipteran (insect, with half of its anterior wings being coriaceous), etc. The ancient Greeks used the suffix –ion to form diminutives. By adding it to the root pteryx, they formed the word pterygion, ie, small wing. The same suffix created diminutives of many other words. Phlebion, a small blood vessel, venule, arteriole or capillary, was derived from phlebs, and pyramidion, the upper vertex of the pyramid, was derived from pyramis, pyramid.1 The diminutive pterygion was initially applied to the fins of fish and the wings of insects and small birds, but in the Hippocratic scripts, it was also used to refer to the conjunctival invasion of the cornea, because of its similarity to a small wing (Figure 1).2 The Greek suffix -ion has survived to the present, but it is no longer used to express diminutives. In modern-day Greek, the diminutive is formed with the suffix –aki. During the course of history, Republican and Imperial Rome incorporated many Greek terms, some of which were used widely over a long period and others that were used rarely and disappeared rather quickly. Among them was pterygion, referring to the trigonal conjunctival growth over the lateral parts of the cornea, but the Romans, instead of taking the Greek root pteryxand adding to it any one of the many Latin diminutive suffixes (-elus, -olus, -ulus, -culus), took the complete term pterygion and Latinized it as pterygium. Maybe the nonGreek-speaking Romans understood pterygion not as a diminutive, but as a neuter name, with plural in –a. However, the word pterygium remained in the papyri and never entered the common Latin language, which already had a name for this disease; it related not to a small wing but to a nail, unguis, or its diminutive, ungula, or a cloth, pannus. The Romanization of southern and mid-Europe, West Asia, and North Africa diffused the Latin word unguis when Latin spread to other countries, and many dialectal forms appeared. The more common the disease pterygium was in a country, the more frequent were its terminological variants, and the more it was mentioned in general speech, the more widespread became the use of its colloquial name. Therefore, the terms were maintained for centuries, when an illiterate population lived in a limited and closed environment. The vernacular lexical variants for expressing the concept of pterygium depend less on the evolution of some assimilated common roots3 and more on the analogies sought to describe the external aspect of the conjunctival and corneal invasion. When a name for pterygium appeared spontaneously in a culture, it usually took the name of an object that resembled this eye disease (wing, nail, spike, tassel, palm, etc.), initially adding “in the eye.” Gradually, if the disease was very common, or if the term became established to mean pterygium, which was by definition an ocular condition, “in the eye” was dropped from the terminology. Thus, in the Canary Islands, pernal probably was initially pernal en el ojo (leg on the eye), but the disease was frequent due to the intensity of sunlight in that region, and it became known simply as pernal, which all people interpret as pterygium.