DISEASES OF THE EYE. 113 



ISilTIS. 



The Iris { a rainbow ) has received its name from the varied color it pre- 

 sents. It is a thin, circular shaped, contractile curtain suspended in front 

 of the lens, heing perforated hy an aperture, the pupil, for the transmis- 

 sion of light. 



The perfection of the eye is very much Increased by the action of this 

 curtain. In a strong.light the pupil contracts and shuts out the superfluous 

 rays ; in a feeble light it dilates in order to admit into the eye all the light 

 which can be received. ~ 



The iris is liable to inflammation. While the name iritis is used to indi- 

 cate a distinct affection, it is rarely that Inflammation is confined to the 

 iris alone, but parts anterior to it, and the deeper structures behind It are 

 involved. 



Causaiion. —The affection may be the result of injuries, over-exertion, 

 or caused by various morbid states of the blood. 



^mploms. — The white of the eye changes to a bright pink hue. The 

 iris at first becomes indistinct, losing its color; the pupil is contracted, 

 and its inner edges are irregular. In the next stage, one of effusion , the sur- 

 face appears in some cases rusty ; in others a film closes the pupil. In veiy 

 acute cases the conjunctiva becomes affected by the Inflammation. Pain , 

 restlessness, intolerance of light, and excessive flow of tears are the com- 

 mon associate symptoms. 



Prognosis . — If the disease is of recent origin the prognosis is favorable. 

 If it has existed for a long time and came on slowly and insidiously , the 

 chances of recovery without impairment of sight are doubtful. 



Trealmeni. — To allay pain, and guiet restlessness, paregoric in tea- 

 spoonful doses can be given. To subdue inflammation, the bowels should 

 be moved freely by epsom salts, and the diet be restricted to milk, broths, 

 raw eggs, etc. 



To preserve the pupil entire, it should be kept well dilated by means of 

 a solution of the sulphate of atropine (gr. 1 ad. aquae distU. Ji.) Of this a 

 few drops should enter the eye morning and night. 



If the animal is full blooded, strong and hardy, " Gray powder " in one 

 grain doses may properly be given three times a day between the feedings. 

 This mercurial should only be continued for four or five days. After the 

 acute inflammation has subsided, the iodide of potassium may be given 

 three times daily in three grain doses. If the animal is debilitated the 

 syrup of the iodide of iron is advised in ten drop doses at each feeding. 

 If the need is apparent cod liver oil may also be added to the treatment. 

 The tonics should be persisted in until the fllm disappears, leaving the 

 pupil clear. 



