62 SURGICAL APPLIED ANATOMY. [Chap, iv 



the opaque debris is left to the aqueous, and it is not 

 long before its efficacy in that direction is seen. 



The vitreous takes little active share in ocular 

 maladies. It may be secondarily affected in innamina- 

 tion of adjacent parts, may be the seat of haemorrhages, 

 and is often occupied by opaque bodies of various 

 kinds. Foreign bodies have lodged in the vitreous 

 for considerable periods without causing any symp- 

 toms. The muscae volitantes that so often trouble the 

 myopic are due to little opaque matters in the vitreous, 

 and very often have exactly the appearance that the 

 corpuscles of the vitreous present when seen under 

 the microscope. 



The vitreous is readily separated from the retina 

 except behind, opposite the disc where the artery to 

 the lens enters in the foetus. 



This vessel is a branch of the central artery of the 

 retina, and may persist as a fibrous cord in adult life. 

 In some rare cases it has continued to transmit blood, 

 and in such instances its pulsation can be seen by the 

 ophthalmoscope. 



Glaucoma is a disease the symptoms of which 

 are all dependent upon an increase in the intraocular 

 tension of the globe. The increased tension is due 

 to an excess of fluid within the eye-ball, and this would 

 appear to be due to certain changes, seldom absent 

 in the glaucomatous, that interfere with the normal 

 escape of this fluid. Normally there is a constant 

 movement of fluid from the vitreous through the 

 suspensory ligament into the posterior chamber, and 

 thence round the pupillary margin of the iris to the 

 anterior chamber. This fluid is derived mainly from 

 the ciliary body, and in. a less degree from the pos- 

 terior surface of the iris. Atrophy of the epithelium 

 on the ciliary body is said to lead to diminished ten- 

 sion. From the anterior chamber the fluid can escape 

 into the v?ins through the gaps in the ligamentum 



