THE LYMPHATIC SYSTEMS OF THE EYE 673 



anastomose with the vessels of the choroid; other branches pass into 

 the iris and, converging toward the visual axis form, just outside the 

 pupillary margin, a second circle of anastomosis, the circulus minor. 



The veins of the iris and ciliary body follow closely the distribution 

 of the arteries, the greater portion of their blood returning through 

 the veins of the choroid and the vena3 vorticose. Some, however, is 

 returned by means of anastomoses with the anterior ciliary veins. 



4. The anterior ciliary arteries, derived from the muscular and 

 lacrimal branches of the ophthalmic, distribute branches to the con- 

 junctiva and sclera, and within the latter membrane, about 2 mm. outside 

 of the corneal margin, pass to the circulus iridis major and partially 

 supply the iris and ciliary body as already described. 



The anterior ciliary veins follow the course of the corresponding 

 arteries. They empty into the vessels of the ocular conjunctiva. 



THE LYMPHATIC SYSTEMS OF THE EYE 



The lymphatic systems of the eye include very few true lymphatic 

 vessels, but consist rather of a series of channels which may be arbitrarily 

 considered as an anterior and a posterior set of intercommunicating 

 spaces. The former set includes the lymphatic spaces of the cornea, 

 the spaces of Fontana, the anterior and posterior chambers, the lymphatic 

 clefts of the ciliary muscle and iris, and the zonular spaces or canals of 

 Petit. The posterior set includes the subdural and subarachnoid spaces 

 in the sheath of the optic nerve, the capsule of Tenon, the lymphatic 

 spaces of the lamina suprachoroidea, the perivascular spaces of the 

 choroid and retina, the irregular clefts between the pigmentary and 

 bacillary layers of the retina, the similar clefts of the ganglion cell 

 layer, the lymphatic spaces of the hyaloid membrane, the hyaloid canal, 

 and the interstices of the vitreous humor. 



These two sets of lymphatic channels communicate with each other 

 by means of the perivascular spaces of the two outer tunics, as well as 

 through that portion of the hyaloid membrane which forms the posterior; 

 wall of the spatia zonularis, through the clefts of which and the hyaloid 

 canal the lymph of the vitreous body communicates freely with the 

 aqueous humor of the spatia zonularis and posterior chamber. Conse- 

 quently, if the cornea be penetrated either accidentally or otherwise, 

 and the anterior and posterior chambers be emptied, their aqueous 

 humor is rapidly replaced, not only from the adjacent spaces of the 



