640 THE EYE 



They are disposed in a circular direction about the axial margin of the 

 ciliary body on its outer surface, and hence are in relation with the inner 

 surface of the sclerocorneal junction and the outer margin of the 

 base of the iris. The circular muscle fibers are also interspersed among 

 the fibers of the ligamentum pectinatum, which pass in a radial manner 

 from the margin of the posterior homogeneous membrane of the cornea 

 to the base of the iris and anterior margin of the ciliary body. The 

 circular fibers are said to be deficient or even absent in myopic eyes, but 

 are exaggerated in hypermetropic eyes. 



The disposition of the ciliary muscle fibers is such that during con- 

 traction the fibrous ciliary body and the base of the iris are drawn 

 forward, the choroid is made tense, and the suspensory ligament of the 

 lens is relaxed. The lens then becomes more nearly spherical because 

 of its own elasticity. 



The fibrous layer of the ciliary body consists of connective tissue, 

 and connects the fibrous portion of the choroid to the similar tissue of the 

 iris. It is formed by a reticulum of the fine fibers in the meshes of 

 which are numerous lamellar and a few pigmented cells. Buried within 

 the outer portion of this fibrous mass and intermingling with its fibers 

 are the fiber bundles of the ciliary muscle. Into the inner portion of the 

 fibrous layer a vascular plexus is continued from the vascular and capil- 

 lary layers of the choroid; branches of the ciliary arteries communicate 

 with this plexus. 



Appended to the inner surface of the fibrous layer are numerous 

 meridionally disposed folds of connective tissue which radiate from, the 

 base or outer margin of the iris to the margin of the choroid opposite the 

 ora serrata. These are the ciliary processes. Their inner or free surface 

 is covered by the pigmented retinal epithelium, and within these proc- 

 esses are contained the greater portion of the pigmented connective tissue 

 cells of the ciliary body. Each fold is much deeper (about 1 mm.) 

 toward its axial margin and becomes progressively diminished in height 

 toward the choroid. 



The pigmented epithelial layer is here and there invaginated into 

 the fibrous tissue of the ciliary processes to form ampullate recesses 

 (the ciliary glands), which somewhat resemble true secreting glands. 

 These so-called glands have been supposed to be concerned in the secre- 

 tion of the aqueous humor. They are probably not true secreting glands, 

 but represent mere invaginations of the epithelium. 



The ciliary epithelium (pars ciliaris retinae) consists of a double 

 layer of epithelial cells, continuous posteriorly with the retina, and in 



