258 



The narrowed or obstructed ducts ma^ be made pervious by a fine 

 silver probe passed dowu to the lachrymal sac, and any existing inflam- 

 mation of the passages may be counteracted by the use of steaming 

 mashes of wheat bran, by fomentations or wet cloths over the face, and 

 even by the use of astringent eye washes and the injection of similar 

 liquids into the lachrymal canal from its nasal opening. The ordinary 

 eye wash may be used for this purpose, or it may be injected after di- 

 lution to half its strength. The fractures and diseases of the bones and 

 teeth must bo treated according to their special demands when, if the 

 canal is still left pervious, it may be again rendered useful. 



EXTERNAL OPHTHALMIA — CONJUNCTIVITIS. 



In inflammation of the outer parts of the eye ball the exposed vas- 

 cular and sensitive mucous membrane (conjunctiva) which covers the 

 ball, the eyelids, the haw, and the lachrymal apparatus, is usually the 

 most deeply involved, yet adjacent parts are more or less implicated, 

 and when disease is concentrated on these contiguous parts it consti- 

 tutes a phase of external ophthalmia which demands a special notice. 

 These have accordingly been already treated of. 



The causes of external ophthalmia are mainly those that act locally — 

 blows with whips, clubs, and twigs, the presence of foreign bodies like 

 hay-seed, chaff, dust, lime, sand, snuff, pollen of plants, flies attracted by 

 the brilliancy of the eye, wounds of the bridle, the migration of the 

 scabies (mange) insect into the eye, smoke, ammonia rising from the 

 excretions, irritant emanations from drying marshes, etc. A very dry 

 air is alleged to act injuriously by drying the eye as well as by favoring 

 the production of irritant dust; and the undue exposure to bright sun- 

 shine through a window in front of the stall, or to the reflection from 

 snow or water, is undoubtedly injurious. The unprotected exposure of 

 the eyes to sunshine through the use of a very short overdraw check is 

 to be condemned, and the keeping of the horse in a very dark stall from 

 which it is habitually led into the glare of full sunlight, intensified by 

 reflection from snow or white limestone dust, must be set down among 

 the locally acting causes. But exposure to cold and wet, to rain and 

 snow storms, to cold draughts and wet lairs must also be accepted as 

 causes of conjunctivitis, the general disorder which they produce affect- 

 ing the eye, if that happens to be the weakest and most susceptible 

 organ of the body, or if it has been subjected to any special local injury 

 like dust, irritant gases, or excess of light. Again, external ophthalmia 

 isaconstant 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 sncli cases, however, the 

 afiection of the eye is subsidiary and is manifestly overshadowed by the 

 primary and i^redominatiug disease- 



