DISEASES OF THE EYE. 287 



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 speck or fleecy 

 cloud, but too often blood vessels begin to extend from the adjacent 

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

 portion of the cornea is rendered permanently opaque. 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 that may pene- 

 trate more or less deeply and leave a breach in the tissue which, if 

 filled up at all, is repaired by opaque fibrous tissue in place of the 

 transparent cellular structure. Pus may form, and the cornea as- 

 sumes 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 inflamma- 

 tion of the conjunctiva may be simply catarrhal, with profuse muco- 

 purulent discharge; it may be granular, the surface being covered 

 with minute reddish elevations, or it may become the seat of a false 

 membrane (diphtheria). 



Treatinent. — In treating external ophthalmia the first object is the 

 removal of the cause. Remove any dust, chaff, thorn, or other for- 

 eign body from the conjunctiva, purify the stable from all sources of 

 ammoniacal or other irritant gas; keep the horse from dusty roads, 

 and, above all, from the proximity of a leading wagon and its attend- 

 ant cloud of dust ; remove from pasture and feed from a rack which 

 is neither so high as to drop seeds, etc., into the eyes nor so low as to 

 favor the accumulation of blood in the head ; avoid equally excess of 

 light from a sunny window in front of the stall and excess of darkness 

 from the absence of windows; preserve from cold drafts and rains 

 and wet bedding, and apply curative measures for inflammation of 

 the adjacent mucous membranes or skin. If the irritant has been of a 

 caustic nature, remove any remnant of it by persistent bathing with 

 tepid water and a soft sponge, or with water mixed with white of egg, 

 or a glass filled with the liquid may be inverted over the eye so that 

 its contents may dilute and remove the irritant. If the suffering is 

 very severe, a lotion with a few grains of extract of belladonna or of 

 morphia in an ounce of water may be applied, or, if it is available, 

 a few drops of 4 per cent solution of cocaine may be instilled into 

 the eye. 



In strong, vigorous patients benefit will usually be obtained from a 

 laxative, such as 2 tablespoonfuls of Glauber's salt daily, and if the 

 fever runs high from a daily dose of half an ounce of saltpeter. As 

 local applications, astringent solutions are usually the best, as 30 

 grains of borax or of sulphate of zinc in a quart of water, to be ap- 

 plied constantly on a cloth, as advised under " Inflammation of the 



