RETINAL HEMORRHAGE.
This occurs in inflammations of the retina or choroid, also in degenerations of the vascular walls and as a result of traumas, or poisons. Schindelka quotes a case in a dog from ptomaines, Eversbusch, one from scurvy in the dog, Appenroth, one in a calf from a blow with a cow’s horn, and others in cats and horses from traumas. It is present to a slight extent in all inflammations of the retina. With the ophthalmoscope the recent lesion appears as a bluish red blotch on a bright red ground, and the older lesion of a brownish red. Rest and a pressure bandage may be employed after subsidence of the inflammation.
TUMORS OF THE RETINA.
Eversbusch found subretinal cysts in a 24 year old horse, Merkel and others have found similar bodies in old dogs and cattle. Sarcomata and melanosarcoma are found on the surface of the choroid in gray horses, implicating the retina. The only remedy is enucleation of the bulb.
INFLAMMATION OF THE OPTIC NERVE. PAPILLITIS.
Choked disc. Neuro-retinitis. Papillo-retinitis. Nerve swelling blocks veins. Causes: lead, tumors in brain bilateral, in orbit unilateral, influenza, petechial fever. Symptoms: redness of optic disc, retinal arteries contracted, 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 compress 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 petechial fever, heart failure and dyspnœa. In a necropsy on a horse the writer found complete cataract, atrophy of the bulb to less than two-thirds the size of its fellow, thickening and furrowing 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.
Symptoms. To the phenomena of retinitis there is added violent injection of the capillary plexus of the papilla. The arteries of the retina are contracted while the veins are dilated and tortuous. The papilla is swollen and is said to have a woolly appearance. The vitreous may be opaque by reason of exudation or blood extravasation into its substance. Retro-ocular neuritis is usually present, and brain tumor in certain cases. Möller 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 pupil may be at first strongly contracted and later freely dilated.
Treatment is usually of little avail and does not differ materially from that adopted in retinitis. In tumor of the orbit pressing on the optic nerve it may sometimes be reached through the temporal fossa, but usually in all such cases enucleation of the eyeball is demanded.