7 8 



APPLIED ANATOMY. 



or focussing power of the eye. The ciliary processes are formed of convoluted 

 blood-vessels supported by connective tissue and covered by the pigmented exten- 

 sion of the retina. This ciliary region is an exceedingly sensitive one and a serious 

 wound of it usually means a loss of the eye. 



Cataract. When the lens is opaque it constitutes the disease known as cata- 

 ract: this name is also applied to opacities of the capsule of the lens. When the lens 

 alone is opaque it is called a lenticular cataract; when the capsule alone is affected, it 

 is a capsular cataract. Both are sometimes involved, constituting a lenticulocapsular 

 cataract. The lens is made up of layers like an onion. Some. of these layers may 

 become opaque, leaving a surrounding rim of clear tissue. The nucleus within the 

 affected layer is also clear. This form is called a zonular or lamellar cataract. A 

 capsular cataract may affect the anterior portion of the capsule, forming an anterior 

 polar cataract, or the posterior layer of .the capsule, forming a posterior polar cataract. 



If the cornea has been perforated by a central ulceration, the aqueous humor 

 escapes, the lens falls forward, and its anterior capsule becomes adherent at the site 



Lens 



Suspensory ligament of lens 

 Canal of Schlemm 

 Ciliary process 



Conjunctiva 



Cornea 



Anterior chamber 

 Iris 



Posterior chamber 



Sclerocorneal juncture 



Tendon of in- 

 ternal rectu 

 muscle 



Vena vorticosa 



Tendon of 

 external rectus 

 muscle 



Vitreous 



Sclera 



Ciliary nerv 



Posterior ciliary vessels 



Hyaloid canal 



Optic nerve 



Central retinal vessels 



Optic papilla 



Retina 

 Fovea centralis 



FIG. 93. Diagrammatic horizontal section of right eye. X 3*A- (Piersol.) 



of perforation. As the aqueous humor reaccumulates, it pushes the lens back, leaving 

 a small portion of inflammatory tissue clinging to its anterior capsule, thus forming 

 an anterior polar cataract. A posterior polar cataract is the result either of disease, 

 such as choroiditis, in which the posterior capsule becomes involved, or of a persistence 

 of the remains of the hyaloid artery, a fetal structure. 



Secondary cataracts are the opacities of the capsule or inflammatory bands 

 and tissues which are left, or which occur, after the removal of the lens. The lens in 

 childhood is soft; it grows harder as age increases. If the aqueous humor obtains 

 access to the lens through a wound of the anterior capsule, the lens becomes opaque, 

 constituting a traumatic cataract. In operating for cataract in childhood, the lens, 

 being soft, is first rendered opaque by the aqueous humor admitted through a 

 puncture made in the capsule ; if it is admitted repeatedly to the lens by the 

 surgeon's needle (needling or discission operation) the lens matter is completely 

 dissolved. The fluid lens matter can also be removed by a suction instrument. 

 In old people the nucleus becomes hard and opaque, forming a senile cataract. 



