KERATOCENTESIS 



'73 



cataract knife is then thrust carefully through the cornea 

 near the inferior part of the corneo-sclerotic margin. The in- 

 cision is made perpendicularly, that is to say, at a right angle 

 to the margin and not parallel to it. The corneal vessels 

 which radiate toward the center at right angles from the 

 corneo-sclerotic margin, and which, owing to inflammation, 

 are often perceptible, are thus avoided. Horizontal incision 

 along the corneo-sclerotic margin, in eyes affected with in- 

 flammatory conditions, provokes bleeding into the chamber 

 that defeats the purposes of the operation by obscuring the 

 object to be removed. 



The incision, which need not exceed one-sixteenth of an 



Fig. 34 — Position of Incision in Keratocentesis for Periodic Ophthalmia. 



inch in length, is made inferiorly, because it is here that the 

 morbid products to be removed have precipitated. Incisions 

 made superiorly may answer well enough for the abstrac- 

 tion of helminths or floating particles, but for the treatment 

 of periodic ophthalmia whose aim is the evacuation of precip- 

 itated septic products, the puncture must be made inferiorly. 



The reader may be profitably warned that the cornea is 

 an exceedingly tough integument, the incising of which re- 

 quires a keen cutting knife. 



Third Step. — -Evacuating the Aqueous Humor. — Abstrac- 

 tion of Coagula, Helminths, etc. — In the treatment of simple 

 cases of periodic ophthalmia the aqueous humor is rapidly 

 evacuated by pressure upon the globe while the point of the 

 wire hook keeps the incision open. If pieces of coagulated 

 humor block the incision, they are hooked out and the evacu- 



