PERIODIC OPHTHALMIA. 79 



attack is influenced or produced by dental irritation. Mr. Spooner 

 has suggested the name '' hereditary ophthalmia." Mr. Croxford, 

 a student at the time, pertinently asks why it may not be called 

 " constitutional ophthalmia." 



The Symptoms, together with the little history attached to 

 them, are in general sufficient to mark the presence of this disease. 

 From its commonly making its attack during the night, the groom 

 discovers, on entering his stable in the morning, that his horse 

 has got " a weak eye;" which, in reporting either to his master or 

 to the veterinary attendant called in, he seldom fails to attribute to 

 *^a blow" or "bite" accidentally inflicted some time in the night, or 

 else to ''something having got into the eye:" and, indeed, the half- 

 closed aspect of the eye itself very much favours this fallacy of the 

 groom's. 



The upper lid droops upon the cornea to shut out the glare of 

 light. Tears are produced in that abundance that they cannot be 

 carried away by the puncta lachrymalia, and are consequently 

 overflowing their natural boundary, the lower eyelid, and stream- 

 ing down upon the face. Both eyelids, together with the venous 

 vessels in the immediate vicinity of the eye, are tumid or fuller 

 than ordinarily. What little is visible of the globe of the eye 

 appears dull and sunken. The organ is intolerant of light; 

 and especially evinces this when suddenly confronted with the 

 strong rays emitted through the door or window of the stable, by 

 momentary nictitation, and by recoil within the orbit and simulta- 

 neous protrusion of the haw. Seizure of the upper lid by its 

 lashes, and attempts to evert it, cause the ejection of the haw*, 

 and aflbrds us an enlarged view of the membrana conjunctiva, 

 reddened and injected through inflammation, commonly of the sub- 

 acute character, and more or less tumid from infiltration. The 

 circumference of the cornea sometimes exhibits a broad nebulous 



* When the object is to inspect the interior of the eye, the intrusion of this 

 troublesome visitor is best guarded against by opposing the bulbous end of a 

 large probe against it. Without such compulsory means, however, a sufficient 

 view of the eye is often obtainable — before any disturbance has been given to 

 it — by turning the horse's head into a situation where the light is subdued, 

 and yet enough for the purposes of inspection. 



