362 
PERIODICAL OPHTHALMIA OF HORSES. 
dinary to offer upon the subject which I have chosen for a few 
observations on the present occasion; but as it is a point of our 
practice that appears to be still involved in much obscurity—a 
disease of a Protean character, whose true nature it seems dif¬ 
ficult to grasp—it appears to me that it must always be useful 
to collect facts; to trace predisposing and exciting causes; 
and, in short, to note every circumstance relative to such a com¬ 
plaint ; as such investigations afford the best, if not the only, 
means of arriving at a satisfactory conclusion. 
This is a species of ophthalmia quite peculiar to the horse, and 
differing essentially from any variety of the disease bearing that 
name, to which the human eye, or, as far as we know, that of 
any other animal is liable; inasmuch as that it invariably puts 
on an intermittent character. It occurs by paroxysms; and the 
means employed to relieve or cut short one attack of inflamma¬ 
tion, however apparently successful at the time, do not appear 
to have the least effect in preventing its recurrence, or of arrest¬ 
ing its final termination in cataract. 
Its periodical character may, therefore, be said to constitute 
its most remarkable feature ; and this circumstance is so striking 
in itself, that it seems always to have attracted particular notice 
at all times and in all ages. Hence we constantly find in old 
books of farriery the terms “ moon blindness,’’ “ lunatic eyes,” 
designating the complaint. The old practitioners, many of whom 
we must allow were men of observation, seeing that the disease 
generally pursued a regular course, and that the attacks of in¬ 
flammation constantly recurred after certain intervals, naturally 
enough concluded that these were influenced by certain states 
and changes of the moon. “ Now they be called moon eyes,” 
says our earliest author, old Gervaise Markham; “ because, if 
the farrier do observe them, he shall perceive that at some times 
of the moon the horse will see very prettily, and at some times of 
the moon he will see nothing at all. Now the signs thereof are, 
when the horse’s eyes are at the best they will look rather yel¬ 
lowish and dimme; and when they are at the worst, they will 
look red, fiery, and angry.” I have quoted this from Markham's 
“ Masterpiece,” to shew the origin of the absurd terms “ moon 
blindness,” “ moon eyes,” &c. we so often meet with. But with 
almost equal absurdity in more modern times we have heard 
the malady in question designated “ the gouty inflammation of 
the horse’s eyeand this in reference only to its intermittent 
character ; for its hereditary tendency, by which, indeed, it may 
fairly be said to lay claim to some analogy with gout, has not, I 
think, until very lately been admitted. I recollect, when at the 
Veterinary College, observing to our worthy Professor, Mr. Cole- 
