19
aqueous humour loses its transparency and assumes a milky tint, the cornea becomes thickened
and gradually opaque ; then the inflammatory phenomena subside, but vision is destroyed.
In exceptionable cases a small quantity of blood may escape into the anterior chamber. Accord-
ing to Spooner-Hart " the opacity of the cornea arising from the presence of a worm differs
from that resulting from an injury which is always thickest at the immediate seat of the
trouble or blow; whereas an opacity arising from the presence of a worm is evenly diffused
all over the cornea and is regularly characteristic and diagnostic.
In the early stages of the tenancy of the worm the opacity is thin and pale, and as already
mentioned, after a time, becomes dense and presents a sort of marbled appearance. In the
early stages the opacity may clear just as quickly as it comes on; as the worm shifts from
the front to the back of the iris, and the irritation is further removed from the cornea, it clears
up ; but as can be readily understood, this is not capable of frequent repetition. In addition
to opacity of the cornea, there is lachrymation and more or less constant spasmodic twitching
(blepharospasmus) of the upper lid, which in some instances may be in a half-drooping condi-
tion ; but, as a rule, there is little intolerance of light."
Adams states that he has met with cases in which for several days there has been a general
weakness of the eye and an intolerance of light before the worm became visible. Opacity he
says is a very frequent but not a constant complication ; it generally clears up after operation;
if, however, the opacity is well marked before puncture of the cornea is performed, it may
never clear at all. This officer mentions a case of some interest where the worm had been
present for about three weeks before the horse was sent to him, there was no excessive opacity
of the cornea, but the sight was injured and the humours of the eye were dimmed. The
worm was removed and the horse sent back to its owner, who stated that, although for a long
time the cornea appeared dull, it eventually became quite transparent again.
As a rule, only one eye is affected and one filaria present, but cases have occurred where
as many as three worms have been observed in the same organ at the same time. Hart
mentions that " he removed a worm, and it was followed by another in the same eye a fort-
night later." Further, on another occasion " he removed one in the near eye, and it was
followed by one in the off eye."
Season and Rainfall—From a record of 18 cases of Filaria Oculi which occurred at the
Hossur Government Depôt (Madras), under the observation of Veterinary-Surgeon W. S. Adain'
Army Veterinary Department, it was found that the numbers in each month were as follows:—
January 2, February 4, March 5, April 1, May 3, June 0, July 0, August 0, September 1, Oc-
tober 1, November 1, December 0 So that fifteen (15) cases occurred in the first five months of
the year, during which the total average rainfall was only 8.6 inches, equal to about one quarter
of the average total for the year. Eleven of the fifteen cases occurred during the first three
months, during which only 1.8 inches on an average fell. The frequency of the disease varies
much in different years ; in 1871-72, there were two cases, then an interval of three years, during
which there was no case. From 1875 to 1877, inclusive, four cases, followed by an interval of
two years; in 1880, there were three cases, then another interval of two years. Three cases
occurred in 1883, none in 1884, one in 1885. During February and March 1886, five cases
were diagnosed.
Acoording to Spooner-Hart, this affection of the eye is " prevalent in the plains of
Lower Bengal, in the delta of the Ganges, and in parts more especially which are flooded
during the monsoon or rainy season, such districts favouring the development of the parasite."
Geographical Range.—This helminthiasis is most commonly observed in horses in India
and Ceylon, but is exceptionally seen in China, Europe and America. Large Epizootics are
recorded as having occurred amongst bovines in France and Belgium. But to show the
frequency with which it is found in India, it is only necessary to mention the fact that the
cultivators inhabiting the numerous districts of the North-West Provinces, the Punjab,
Bengal and Madras recognise the affection of the eyes and have special names by which it
is known.
During the past five years, I have been able to collect some notes concerning 71 cases
of Filaria Oculi, which have occurred amongst the remounts purchased or bred at the Gov-
ernment Depôts situated at Karnal and Saharanpur, and of the above have received for
microscopical examination 18 filariæ removed from the eyes of as many horses, principally
country-breds, but including three Australians. I would here take the opportunity of
offering my best thanks to the undermentioned officers for the kind assistance they have,
at all times, so generously afforded me, and without which I should have been unable to
investigate the interesting subject of Filaria Oculi:—
Captain G. D. Birdwood, Superintendent, Karnal.
Veterinary-Captain S. M. Smith, Saharanpur.
Veterinary-Lieutenant F. Eassie, Karnal.
Veterinary-Lieutenant T. G. Peacock, Karnal.
As 70 per cent. of the cases of Filaria Oculi occurred at the Karnal Dep6t between
February 1892 and February 1898, and as more facts are forthcoming with regard to the
animals reared at this than at the other depôt, it is my intention first shortly to describe