458 CLINICAL APPLIED ANATOMY. 



from the deeply situated arteries of the adjacent sclerotic, and 

 hence they appear to come out from beneath the limbus. They 

 are often quite indistinct, and of a dirty red or greyish-red 

 colour, because they are covered by the clouded superficial layers 

 of the cornea. They are easily distinguished from the superficial 

 vessels, not only by their position and appearance, but also by 

 the fact that their branches are given off in tufts, like a brush, 

 whilst in superficial keratitis they branch in arborescent fashion. 

 Traces of these vessels can often be detected as thin parallel 

 fibres after all sign of interstitial keratitis has passed off a point 

 of some importance in determining the presence of congenital 

 syphilis. 



The opacities following upon corneal inflammation may be 

 placed in its most superficial layers, when the keratitis has only 

 damaged the surface epithelium. Nebula deeper in its substance 

 are most commonly the outcome of interstitial inflammation. 



Perforating wounds of the cornea, when occurring near the 

 periphery, allow of the escape of aqueous humour from the 

 anterior chamber, and possible prolapse of the iris, particularly 

 when the pupil is dilated ; hence the value of eserin for the 

 prevention of the extrusion of the iris. In the same way it may 

 happen that the iris, though not extruded, becomes attached to 

 the posterior surface of the cornea at the site of the perforation, 

 and a permanent anterior synechia is formed. In some instances, 

 after perforation of the cornea, the lens itself is pushed forward 

 during the escape of aqueous, so that its anterior capsule becomes 

 applied to the posterior surface of the cornea. This sets up an 

 irritation which produces a permanent opacity in the anterior 

 capsule, known as an anterior polar cataract. 



During the progress of an ulcer of the cornea, its tissue may 

 become so thinned that the normal intra-ocular pressure may 

 induce a bulging forward of the posterior lamellae, known as 

 keratectasia. 



Wounds of the sclero-corneal junction are most dangerous 

 when septic, owing to the great risk of so-called " sympathetic 

 ophthalmitis." It is probable that in the majority of such cases 



