750 



OPERATIONS UPON THE EYE AND EAR. 



the posterior rectus muscle is drawn back in the orbital cavity, a 

 displacement which not only renders the action of the instruments 

 more difS.cult, but also stimulates the motion forward, over the 

 cornea, of the membrana nictitans. The immobility of the eye is 

 one of the first points to be secured. There are two ways of 

 securing it, one fixing it from the front, the other from behind. 



It can also be fixed from the front in two ways — that of Le- 

 blanc and that of Brogniez. Leblanc uses a tricuspid stylet (Fig. 

 540), which has three branches, two of which are applied on the 



Pig. 540.— Tricuspid Stylet of Leblanc. 



sclerotic at the internal angle of the eye, the third, which is mov- 

 able, resting also on the same membrane at its inferior part. The 

 first two keeps the membrana nictitans from the cornea, and aU 

 three, implanted into the sclerotic, keep the globe immovable. 



Brogniez uses a special instrument, which he calls a " diapta^ 

 tor" (Fig. 541), which is a metallic rod, having three or four 



Pig. 341.— Brogniez Diaptator. 



points, twisted Hke those of a cork-screw, which by a sUght 

 pressure, combined with a Little twist of the instrument, com- 

 pletely fixes the ocular globe. 



To fix the globe from behind, Hayne, Dieterichs, Prinz and 

 Bleiweiss make an incision through the skin behind the orbital 

 arch, and an assistant, with one of his fingers passed through it, 

 keeps it in place by direct pressure. 



General anesthesia is always indicated. Peuch and Toussaint 

 recommend the use of the Waldon forceps (Fig. 542) to immobU- 



Fia. 542.— Forceps oJ Waldoii. 



