84 PERIODIC OPHTHALMIA. 



more than six to fifty, or of one in eight or nine. Not, however, 

 that the healthy eye escapes : on the contrary, after the cessation 

 of the paroxysm in one eye — unless the first attack should have 

 proved violent enough to destroy that eye, which is but rare — the 

 opposite eye will most likely receive the succeeding attack : 

 though sometimes the disease relapses in the same eye. This 

 propensity to attack the eyes alternately has raised a question 

 among veterinarians, whether it arise from the known sympathy 

 existing between the visual organs or be the offspring of the same 

 predisposition and excitement which produced the disease in the 

 eye first invaded. The rapid and complete destruction of the dis- 

 eased eye being found to be an omen of security to the sound one, 

 has appeared to favour the notion of sympathy being the influential 

 agent ; and on such a supposition it has been proposed, as an expe- 

 dient for saving one eye, to put out by artificial means that which 

 was in a state of disease. Supposing there existed any good 

 grounds for putting faith in this theory of si/mpathy, there might 

 be some reason or excuse for a practice revolting in itself to our 

 best feelings : as, however, this cannot be shewn to be the case, 

 but, on the contrary, the attack on the other eye appearing to be 

 no more than we. might expect from the admitted constitutional 

 nature of the disease, this desperate operation has met with no 

 supporters. 



Relapses are looked for as a matter of course. There are 

 instances of horses being fortunate enough to have experienced but 

 one attack, and that not of a destructive character ; and, as I already 

 stated, cases have occurred in which a single attack has deprived 

 the organ of vision : these, however, are both exceptions to the 

 general rule of progress. Ordinarily, the disease, after attacking 

 one eye, rielapses in the other, and continues this alternation until 

 the animal is rendered totally blind by its ravages, the work of 

 destruction being, as I observed before, commonly effected, as it 

 were, by instalments. It is not the violence of the disease that 

 we have to dread so much as these vexatious relapses. The eye 

 is enabled, perhaps, with the veterinarian's aid, to " weather the 

 storm," and come tolerably clear out of the attack ; hardly, how- 

 ever, has it regained its usual lustre, and is beginning to be useful 



