INFLAMMATION OF THE OPTIC NERVE. PAPIEEITIS. 



Choked disc. Neuro-retinitis. Papillo-retinitis. Nerve swelling blocks 

 veins. Causes : lead, tumors in brain bilateral, in orbit unilateral, influenza, 

 petechial fever. Sjanptoms : redness of optic disc, retinal arteries con- 

 tracted, veins gorged, papilla swollen (woolly), vitreous opacity. Treatment. 



This is also known as choked disc from the obstruction of the 

 return of blood by the veins of the retina which pass out at the 

 cribriform lamina. The swelling of the nerve ending and papilla 

 compre.ss the veins, causing stagnation and venous congestion in 

 the retina. When the retina is thus involved the term neuro- 

 retinitis or papillo-retinitis is often applied. 



Causes. The condition has been traced to lead poisoning, 

 brain or orbital tumors, and various infectious diseases. Except 

 in orbital tumor the disease is usually bilateral. In horses 

 Schindelka has seen the condition in influenza and Peters in pe- 

 techial fever, heart failure and dyspnoea. In a necropsy on a 

 horse the writer foiuid complete cataract, atrophy of the bulb to 

 less than two-thirds the size of its fellow, thickening and furrow- 

 ing of the sclera, the presence of an extensive old blood clot in 

 the seat of the vitreous, cupping of the disc, retro-ocular neuritis 

 with exudate inside the sheath, and a considerable reddish brown 

 tumor of the choroid plexus on the same side. The trouble was 

 attributed to the blow of a rope on the eye a considerable time 

 before. The blood in the vitreous retained its dark hue and 

 showed no evidence of microbian invasion. 



Synuptoms. To the phenomena of retinitis there is added vio- 

 lent injection of the capillary plexus of the papilla. The arteries 

 of the retina are contracted while the veins are dilated and 

 tortuotis. The papilla is swollen and is said to have a woolly ap- 

 pearance. The vitreous may be opaque by reason of exudation 

 or blood extravasation into its substance. Retro-ocular neuritis 

 is usually p-resent, and brain tumor in certain cases. Moller calls 

 attention to the fact that with atrophy of the bulb the elliptical 

 outline of the papilla gradually lessens and it becomes more 

 nearly round. In dogs, too, the form of the papilla is also changed 

 and the same author has found it distinctly triangular. The 

 440 



