70 DISEASES OF THE EYES. 



greater cultivation and improvement than the ophthahnic. Dis- 

 eases of the hmiian eye, numerous as they are when compared 

 with those of the generality of other individual organs, and intense 

 and rapid in their progress as some of them are, are most of them, 

 at the present day, treated with an expertness and a success which 

 reflects the highest honours on medical science, and on those who 

 practise it. Veterinary surgery has likewise undergone consider- 

 able amelioration since the days when the projecting haw was cut 

 out for the cure of ophthalmia. Indeed, veterinary surgeons might 

 be expected to avail themselves of the advancement made in this 

 department of art by the human oculist, and to every allowable 

 extent they appear to have done so : but, unfortunately, that ex- 

 tent has its limits. Owing to dissimilarities of structure and function, 

 and consequent differences in pathology, between the eyes of man 

 and horse, and to certain disagreements in the constitutions of the two 

 animal bodies, we are on too many occasions precluded from using 

 the same means, or at least from deriving the same benefit from their 

 use, as are with so much justice extolled by human surgeons. To 

 furnish one example of this : — One of the commonest causes of 

 blindness, both in men and horses, is cataract This the surgeon 

 is no more able to cure, by medicine, than we are ; but he has it 

 in his power to remove the cataract by an operation : he either 

 extracts the opaque body, or couches it out of the axis of vision, 

 and so far relieves and satisfies his patient. But the veterinarian 

 has it not in his power to afford his patient any such relief. 

 When he attempts the operation of extracting or displacing the 

 cataract, the retractor muscle and membrana nictitans — parts not 

 present in the human eye — oppose and foil him in his endeavours ; 

 and, even supposing he were to succeed in the operation, still 

 difficulties present themselves beyond his art or power to overcome. 

 No man from whose eyes cataracts have been removed can see 

 afterwards without glasses to supply the deficiency of the lost 

 lenses : but, could horses wear spectacles 1 And, even if they 

 could, how are we to discover what refracting powers in the glasses 

 the animal requires ; for no two persons hardly are alike in this 

 respect 1 Or, how should we like to ride or to drive horses de- 



