THE EYE 



15" 



of the endothelial layer of the cornea, and they communicate 

 internally with the anterior chamber and the lymph spaces withm 

 the iris, and externallv with the canal of Schlemm. 



Canal of Schlemm (canal of Fontana, simts circularis iridis, or 

 sinus venosus sclerce).— This canal is situated deeply in the sclerotic, 

 close to the comeo-scleral junction. It communicates internally 

 with the anterior chamber through means of the spaces of Fontana, 

 and with the veins of the iris, and externally with the veins of the 

 sclerotic. 



Middle Coat. 



I. Choroid Coat. — ^This is a very vascular, deeply pigmented tunic 

 of a dark brown colour, which lies between the sclerotic and the 

 retina. It extends over the posterior five-sixths of the eyeball, 



Lamina Saprachoroidea{- Z^ 



Arterio- Venous Layer 



Membrana 

 ChoricM;apil 1 aris 



Membrane ef Bruch 



Pigmentary Layer of the Retina 



Fig. 627. — Vertical Section of the Choroid Coat. 

 (The Pigmentary Layer of the Retina is also shown). 



and reaches as far forwards as the ora serrata of the retina. An- 

 teriorly it is connected with the circumference of the iris, and pos- 

 teriorly it is pierced by the optic nerve. Its outer surface is con- 

 nected to the inner surface of the sclerotic by means of the lamina 

 fusca and its processes, as well as by vessels and nerves which cross 

 the perichoroidal lymph-space. Its inner surface is in contact 

 with the pigmentary layer of the retina. 



Structure. — ^The choroid coat consists of connective tissue, blood- 

 vessels, and branched pigment cells. It is composed of three 

 layers, which are as follows, from without inwards : ^i) the lamina 

 suprachoroidea ; (2) the choroid proper ; and (3) the lamina basalis, 

 or membrane of Bruch. 



The lamina suprachoroidea is composed of delicate, non-vascular 

 lamellae, each of which is made up of elastic fibres, arranged in a 

 reticular manner, and of branched pigment cells. 



The choroid proper consists principally of bloodvessels and pig- 



