USTLAMMATION.] 



THE HOESE, AND 



[iNFLAMMATIOIir. 



each of the humours, by its peculiar form and 

 density, contributes to cause a convergence of 

 the rays : the aqueous from its convex form ; 

 the crystalline by its double convexity and 

 greater density than the aqueous; and the 

 vitreous by a less density than the crystalline, 

 joined to its concave form. 



The structure of the eye is in general adapted 

 to the reception of parallel rays ; but, as the 

 distances of visible objects are various, so the 

 eye has powers of accommodating itself to rays 

 proceeding from different distances by altering 

 the distances of the crystalline from the retina, 

 which is done by the action of the ciliary 

 ligaments. We will now speak of the diseases 

 of this organ. 



INFLAMMATION. 



The conjunctiva is that membrane which 

 lines the eyelids, and covers the cornea and 

 the haw of the eye. Its inflammation is one 

 of the most common diseases to which this orb 

 is subject. 



When inflammatory appearances have be- 

 come manifest in this part, the first thing to 

 be ascertained is, whether the transparent 

 cornea is affected or not. One sign is, that 

 the iris, at the border of the pupil, will not be 

 seen without difficulty. Attention must then 

 be directed to the other eye ; and not finding 

 the pupils exactly alike as to size, &c., it may 

 safely be inferred that the smallest is in a state 

 of disease ; the sphincter muscle of the iris 

 having become contracted from sympathy. 

 The next thing to be observed is the blood- 

 vessels of the membrane under the eyelid. If 

 these appear turgid, and even if there is only 

 one of them shooting into the transparent 

 cornea, it is a diseased eye. Attention must 

 then be directed to the glandular bodies at the 

 upper edge of the iris ; and if these are not 

 alike in colour, it may be predicted that the 

 horse will go blind from the effect of little 

 lymph being lodged there from previous inflam- 

 mation. The haw is likewise a criterion to go 

 by. If the haw is not the same in each eye, 

 but one protruding more than the other, the 

 indication is bad. These incipient appearances 

 of this disease are of great importance ; for as 

 this disease is the one to which the horse is most 

 usually subject in the eye, it should be vigilantly 

 watched, as it frequently results in blindness. 

 204 



This disease generally comes on in the night, 

 and is then thought of but little moment ; the 

 groom supposing the eye to be injured by the 

 halter, or by rubbing it against the manger, 

 or some rough place in the stall ; but this is 

 seldom the case ; and, as to producing it by 

 blows, it is exceedingly difficult to wound the 

 eye. If, however, it should be occasioned by a 

 blow, there will be an abrasion on the external 

 surface ; on examining which, it will be easy to 

 determine how to proceed. Take of 



Extract of Saturn ... 4 drachms (| oz). 



Spring water sufficient to fill a common-sized 

 wine-bottle. 

 Apply this lotion frequently every day. Or, 



Take Sulphate of Zinc 1 oz. 



Dissolve in the same quantity of water as 

 above. Either of these recipes, if the inflam- 

 mation arises from a blow, will effect a cure' in 

 a few days. 



This disease does not often attack aged ani- 

 mals, if they have not been previously affected 

 with it. They are most subject to it between 

 four and six years old, when their growth 

 is becoming nearly completed, and when, if 

 highly kept, a plethoric habit is produced ; the 

 solids of the body ceasing to grow, and the 

 deposit of fat becoming greater than the sys- 

 tem requires. Young horses are, in early life, 

 but little susceptible to this disease. When 

 an attack commences, if nothing is done to 

 prevent it, the inflammation increases rapidly, 

 until the pupil is hid, and the whole surface 

 of the eye appears bloody. This, however, may 

 be wholly removed. The attack flies from eye to 

 eye ; first beginning in one, then in the otlier 

 eye, probably at the interval of some months, 

 till one or both become blind. If one only 

 is lost, the general opinion is, that the other will 

 become perfectly sound, and be much stronger. 

 Erom these circumstances it would seem not 

 to be a local disease, but constitutional. It is 

 produced generally by living in a poisoned at- 

 mosphere. In cases where it has appeared, it 

 has been observed that the horses either do 

 not perspire at all, or perspire profusely, from 

 languor. The inflammation having its origin 

 in the conjunctiva, all the other parts partake 

 of it. The iris secretes pus, which falls into 

 the posterior chamber, where absorption takes 

 it up, or probably ulceration takes place. 

 Even the constitution appears to undergo a 



