267' 



body, or if it lias "been subjected to anysijecial local injury like dust, 

 irritant gases, or excess of light. Again, external oplithalinia is a 

 constant concomitant of inflammation of the contiguous and contin- 

 uous mucous membranes, as those of the nose and throat. Hence the 

 red watery eyes that attend on nasal catarrh, sore throat, influenza, 

 strangles, nasal glanders, and the like. In such cases, however, the 

 affection of the eye is subsidiary and is manifestly overshadowed by 

 the primary and predominating disease. 



The symptoms are watering of the ej^e, swollen lids, redness of the 

 mucous membrane exi)osed by the separation of the lids — it may bo 

 a mere pink blush with more or less branching redness, or it may be a 

 deep, dark red, as from effusion of blood — and a bluish opacity of the 

 cornea which is normally clear and translucent. But except when 

 resulting from wounds and actual extravasation of blood, the redness 

 is seen to be superficial, and if the opacity is confined to the edges, 

 and does not involve the entire cornea the aqueous humor behind is 

 seen to be still clear and limx:>id. The fever is always less severe than 

 in internal ophthalmia, and only runs high in the Avorst cases. The 

 eyelids may be kept closed, the eye-ball retracted, and the haw i^ro- 

 truded over one-third or one-half of the ball, but this is due to the 

 pain only and not to any excessive sensibility to light, as shown by 

 the comx3arativel3' widely dilated pupil. In internal ophthalmia, 

 on the contrary, the narrow contracted pupil is the measure of the 

 pain caused by the falling of light on the inflamed and sensitive optic 

 nerve (retina) and choroid. 



If the affection has resulted from a wound of the cornea, not only is 

 that the point of greatest opacity, forming a white sj^eck or fleecy 

 cloud, l)ut too often l>lood-vessels begin to extend from the adjacent 

 vascular covering of the eye (sclerotic) to the white spot, and that por- 

 tion of the cornea is rendered permanently oi)aque. Again, if the 

 wound has been severe, though still short of cutting into the anterior 

 layers of the cornea, the injury may lead to ulceration which may 

 13enetrate more or less deeply and leave a breach in the tissue which, 

 if filled ux? at all, is repaired by oi)aque fibrous tissue in place of the 

 transparent cellular structure. Pus may form, and the cornea assumes 

 a yellowish tinge and bursts, giving rise to a deep sore which is liable 

 to extend as an ulcer, and may be in its turn followed by bulging of 

 the cornea at that point (staphyloma). This inflammation of the con- 

 junctiva may be simply catarrhal, with profuse muco-purulent dis- 

 charge ; it ma}' be granular, the surface being covered with minute 

 reddish elevations, or it maj' become the seat of a false membrane 

 (diphtheria). 



In treafmg external ophthalmia the first object is the removal of the 

 cause. Remove any dust, chaff, thorn, or other foreign bod}' from 

 the conjunctiva, purify the stable from all sources of ammoniacal or 

 other irritant gas; keei") the horse from dusty roads, and above all 



