IRITIS. 459 



the inflammation of the sympathising eye is due to invasion by 

 bacteria, and that the tract along which they travel may be as 

 follows : from the lymphatic spaces of the sclero-corneal 

 junction to the lymphatic tracts in the optic nerve, and so to 

 the optic chiasma : across this structure, and along the lymph 

 vessels of the opposite optic nerve to the opposite eye. 



The cornea is supplied by the long ciliary nerves, derived from 

 the nasal branch of the ophthalmic division of the fifth, and 

 associated with inflammation of these nerves, herpes of the cornea 

 may occur, whilst, if the function of the nerves is in abeyance, 

 ulceration of the cornea frequently follows. 



THE IRIS. 



Iritis. The pain in iritis is felt over the distribution of the 

 ophthalmic division of the fifth nerve, hence the supra-orbital 

 and temporal neuralgia so frequently accompanying this disease. 

 The inflammatory oedema of the iris causes it to lose its lustre 

 and acquire a different colour. For the same reason, and because 

 of the increased amount of blood present in the dilated vessels, 

 the pupil becomes somewhat contracted, and at the same time 

 sluggish in its movements. The pink circumcorneal zone, due 

 to the injection of the epi-scleral vessels, is another indication of 

 the congested state of the part. 



In plastic iritis the exudation on the posterior surface of the 

 iris brings it in contact with the anterior capsule of the lens, 

 inducing adhesion of the two. Such adhesion produces an 

 irregular pupil, and if the connection becomes organised and 

 thereby permanent, a posterior synechia will be present. 



THE CILIARY BODY. 



Cyclitis. Owing to the extraordinary vascularity of the ciliary 

 processes, inflammation occurring in this region is usually 

 accompanied by a considerable amount of oedema and exudation. 

 The exudate first passes into the posterior chamber, where it 



