Text-book of ophthalmology . e lies in the transparent portion of the cornea, and is sol-idly and immovably united to it. The base of the triangle spreads out inthe conjunctiva of the eyeball, and passes into it without there being anysharp line of division between the two. The apex is called the head, the basethe body, of the pterygium. The part that lies between the two and corre-sponds to the margin of the cornea is the neck of the pterygium. Here thelimits of the fold of conjunctiva are the most sharply defined, its bordersbeing inverted in such a way that a small sound (S, Fig. 60) can be
Text-book of ophthalmology . e lies in the transparent portion of the cornea, and is sol-idly and immovably united to it. The base of the triangle spreads out inthe conjunctiva of the eyeball, and passes into it without there being anysharp line of division between the two. The apex is called the head, the basethe body, of the pterygium. The part that lies between the two and corre-sponds to the margin of the cornea is the neck of the pterygium. Here thelimits of the fold of conjunctiva are the most sharply defined, its bordersbeing inverted in such a way that a small sound (S, Fig. 60) can be pushedbeneath them for a short distance. A pterygium of recent origin is succulentand abounds in vessels which run converging from the base to the apex andimpart to the pterygium its red color. In fact, from its similarity in formand vascularity (venation) to the wings of many insects (Hymenoptera),the name of pterygium is The fold of conjunctiva forming the 18 From [irrepvyiov, the diminutive of] nrepv^, a 214 TEXT-BOOK OF OPHTHALMOLOGY pterygium is tightly stretched, so that there are produced a number of radi-ally disposed furrows or flutings; furthermore, in pterygia which are situatedat the inner side of the eye the plica semilunaris is often quite obliteratedand is included in the body of the pterygium (Fig. 60). In the course pursued by a pterygium two stages must be the first the pterygium keeps on gradually growing, for years it may be,toward the center of the cornea, which it may finally reach or even pass(progressive pterygium). Finally, the pterygium comes to a standstill so asto remain permanently attached to the same point upon the cornea (station-ary pterygium). Whether in anygiven case we are dealing with aprogressive or a stationary pteryg-ium is determined mainly by thecharacter of the apex of the the progressive stage this ap-pears surrounded by a gray non-vascular zone which looks thickand gelatinous. In a statio
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecteye, booksubjectophth
