9 2 



The Eye 



Treatment. Unless the tension be promptly relieved, the eye-ball 

 will be ruined. Eserine (Calabar bean), constantly dropped between 

 the lids, may help in this respect by contracting the pupil, and so 

 drawing the iris out of the way of the filtration-angle. But, if the 

 case be acute, iridectomy should be performed. This operation eases 

 the tension by allowing some of the aqueous to escape, and, moreover, 

 the section of the iris extending to its very root, the filtration-angle 

 is inevitably once more opened up. 



From an eye cured of acute glaucoma by iri- 

 dectomy, filtration-angle being opened- 

 out. (PRIESTLEY SMITH.) 



Tumour of iris ; filtration-angle blocked ; 

 secondary glaucoma. (PRIESTLEY 

 SMITH.) 



Looking back, one can now appreciate the peril which a complete 

 anterior or posterior synechia entails (p. 88), and can also understand 

 why some surgeons prefer to preface extraction of the lens by an 

 iridectomy, lest iritis, synechia, and glaucoma should supervene. The 

 preliminary iridectomy, however, is by no means necessary. 



(For the anatomy of the optic nerve see CRANIAL NERVES, 



P- 570 



The retina is the delicate expansion of the optic nerve. It is so 

 thin that the hue of the subjacent choroidal blood is clearly diffused 

 through it, and this, indeed, is all that can be made out in one's first 



