DISEASES OF THE EYE, 289 
digestive organs, may become complicated by this affection. From 
the close relation between the brain and eye—alike in the blood ves- 
sels and nerves—disorders of the first lead to affection of the second, 
and the same remark applies to the persistent irritation to which the 
jaws are subjected in the course of dentition. So potent is the last 
agency that we dread a recurrence of ophthalmia so long as dentition 
is incomplete, and hope for immunity if the animal completes its 
dentition without any permanent structural change in the eye. 
Symptoms.—The symptoms will vary according to the cause. If 
the attack is due to direct physical injury, the inflammation of the 
eyelids and superficial structures may be quite as marked as that of 
the interior of the eye. If, on the other hand, from general causes, or 
as a complication of some distant disease, the affection may be largely 
confined to the deeper structures, and the swelling, redness, and ten- 
derness of the superficial structures will be less markzd. When the 
external coats thus comparatively escape, the extreme anterior edge of 
the white or sclerotic coat, where it overlaps the border of the trans- 
parent cornea, is in a measure free from congestion, and, in the ab- 
sence of the obscuring dark pigment, forms a whitish ring around the 
cornea. This is partly due to the fact that a series of arteries (cili- 
ary) passing to the inflamed iris penetrate the sclerotic coat a short 
distance behind its anterior border, and there is therefore a marked 
difference in color between the general sclerotic occupied between 
these congested vessels and the anterior rim from which they are 
absent. Unfortunately, the pigment is often so abundant in the 
anterior part of the sclerotic as to hide this symptom. In internal 
ophthalmia the opacity of the cornea may be confined to a zone 
around the outer margin of the cornea, and even this may be a bluish 
haze rather than a deep, fleecy white. In consequence it becomes impos- 
sible to see the interior of the chamber for the aqueous humor and the 
‘condition of the iris and pupil. The aqueous humor is usually turbid, 
and has numerous yellowish-white flakes floating on its substance 
or deposited in the lower part of the chamber, so as to cut off the 
view of the lower portion of the iris. The still visible portion of 
the iris has lost its natural, clear, dark luster, which is replaced by 
a brownish or yellowish sere-leaf color. This is more marked in 
proportion as the iris is inflamed, and less so as the inflammation is 
confined to the choroid. The quantity of flocculent deposit in the 
chamber of the aqueous humor is also in direct ratio to the inflamma- 
tion of the iris. Perhaps the most marked feature of internal oph- 
thalmia is the extreme and painful sensitiveness to light. On this 
account the lids are usually closed, but when opened the pupil is 
seen to be narrowly closed, even if the animal has been kept in a 
darkened stall. Exceptions to this are seen when inflammatory effu- 
36444°—16——19 
