CHAPTER VIII. 



THE SCLERA. .' 



The Sclera is a tough,' dense, fibrous structure, con- 

 tinuous with the cornea. Is a Uttle elastic;. Possesses 

 blood vessels, in which it differs from the cornea. Its 

 flbrillse are gathered into bundles and cross each other 

 indiscriminately. Lymph canals ramify through these. 

 The cells are fixed, wandering and pigment. Loose 

 connective tissue covers the sclera in front, and is 

 called episcleral, and this in -turn is covered by the 

 conjunctiva. The sclera is pierced at the inner side of 

 the axis by the optic nerve. This entrance is also 

 below the exact center. This place of entrance is sieve- 

 like and is called the lamina cribrosa, in the center of 

 which is a larger opening, the porus opticus, through 

 which passes the arteria centralis. Surrounding the 

 optic nerve the sclera is perforated by /vessels and 

 nerves called posterior or short ciliary, which go to 

 the choroid, ciliary body and iris. In front it is pierCed 

 by the anterior ciliary vessels. In front the sclera 

 presents an elliptical opening, whose greatest diameter 

 is transverse and whose bprder is bevelled on the inner 



side (remember the bevelling of the cornea), and fits 



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