668 PHYSIOLOGY 



affects seriously the circulation of blood through, the retinal vessels, 

 so that atrophy of the retina is produced together with disturbance 

 of the nutrition of the whole eyeball. This condition of raised intra- 

 ocular tension occurs in the disease known as glaucoma. 



The constant renewal of the intraocular fluid is important not 

 only for the maintenance of the intraocular pressure but also for 

 the nutrition of the structures, such as the lens, suspensory ligament, 

 and vitreous humour, which do not receive any vascular supply. 



