44 SURGICAL APPLIED ANATOMY. [Chap. iv. 



(most often ii^ papillary margin) ?,dherent to the lens 

 cr^ule, by^bands af ; ly,inpSi f eitiier entirely or in one 

 or moi'u different points. Such adhesions constitute 

 -p93,teriQr ; sj^ie^hioB, the t term . a;nte);iof , yynechise being 

 jappiiedj. to .adhesions ,betwe t ei^ she iris arid the cornea. 

 In iritis also the lens may become involved, and the 

 condition of secondary or inflammatory cataract be 

 produced. The iris is not very closely attached at its 

 insertion. Thus, in cases of injury to the eye, it may 

 be torn more or less from its attachments without 

 any damage being done to the other tunics. In one 

 method of making an artificial pupil, known as 

 iridodyalisis, the iris is seized close to its greater 

 circumference by a pair of forceps, and a gap made by 

 forcibly tearing it away from its insertion. In 

 cases of penetrating wounds of the cornea the 

 iris is easily prolapsed. It is so delicate and 

 yielding a membrane, that in performing iridec- 

 tomy the necessary piece of the iris can be 

 seized and pulled out through the cornea! incision 

 without offering sensible resistance. The membrane 

 also derives much support from its contact with the 

 lens, for in cases where the lens has been displaced into 

 the vitreous or has been removed by operation, the 

 iris is observed to be tremulous when the globe is 

 moved. Although very vascular, the iris seldom 

 bleeds much when cut, a circumstance that is pro- 

 bably due to the contraction of the muscular fibres 

 that exist so plentifully within it. Sometimes the 

 iris presents a congenital gap in its substance that 

 runs from the pupil downwards and a little inwards. 

 .This condition is known as coloboma iridis, and is due 

 to the persistence of the " choroidal cleft." In other 

 cases there can be seen, stretching across the pupil, 

 some shreds of the pupillary membrane. Normally 

 this membrane, which is apparent for a few days after 

 birth in some animals, is entirely absorbed before birth. 



