Chap. IV.] 



THE ORBIT AND EYE. 



interstitial keratitis, blood-vessels from the arteries at 

 the margin of the cornea penetrate into the substance 

 of the cornea for some distance. As these vessels will be 

 some little way below the surface, and will be covered 

 by the hazy coriieal tissue that is the result of the 

 disease, their scarlet colour is much toned down, and 

 a strand of such vessels is called a " salmon patch." 

 In the condition known as pamius, the cornea 



Fig. 9. A Horizontal Section of the Globe through the middle. 



a, Cornea ; 5, sclerotic ; c, choroid ; d, retina ; e, lens ; /, iris ; g, ciliary process ; 

 n, canal of Schlemm. 



appears to be vascularised ; but here, owing to con- 

 tinued irritation, vessels, derived from the neighbour- 

 ing conjunctival arteries, pass over the cornea just 

 beneath its ephethelial covering, leaving the cornea 

 proper as bloodless as ever. The term arcus senilis is 

 applied to two narrow white crescents that appear at 

 the periphery of the cornea, just within its margin, in 

 the aged, and in certain morbid conditions. The 



