PERIODIC OPHTHALMIA. 
413 
I might note here that the healthy eye should be examined 
and studied first so that the normal appearance may be 
recognised as well as its differences in disease. 
Method of Operation .—The patient is prepared by diet, 
quiet and darkness immediately. Collyria of atropia used 
morning and night in both eyes, to properly dilate the pupil, 
and prevent a hernia of the iris. If much photophobia is 
present col. of boracic acid or chloride of sodium is used, 
together with a two per cent, solution of cocaine. If much 
opacity and a tendency to ulceration of the cornea, the col. 
of mercury is indicated. Continue this treatment for thirty- 
six to forty-eight hours, then confine your animal for opera¬ 
tion, using a twitch, while an assistant holds the ear with one 
hand and the nose above the false nostril with the other; 
make application of the five per cent, solution of cocaine to 
both eyes, by m ans of absorbent cotton, taking pains to 
render insensible the entire lacrymal sac, and especially the 
membrana nictitans. This generally requires from five to 
ten minutes. When the eye is insensible to the touch of the 
fingers, the self-retaining eye speculum is introduced, and 
with the narrow cataract knife of Von Graefs, modified by 
having it only half the usual length of the blade, an incision 
is made at the lower margin of the cornea and sclerotic, 
midway between the external and internal canthus. This 
operation can be expedited by slight pressure on the cornea 
(previously oiled with almond oil); by allowing the point of 
the knife to remain in the wound the aqueous humor will 
escape. I allow enough to come out so that the cornea has a 
flattened appearance. Care must be exercised that the flow 
of aqueous is very gradual or the lens might be torn from its 
attachments and the iris also involved. The other eye is 
operated upon in the same manner only less aqueous is allowed 
to flow out. This operation on an apparently sound eye, at 
the same time the operation is performed on a diseased one, 
seems to be indicated by experience, for when only one eye 
is treated, the other sooner or later becomes involved. 
The after-treatment consists in the same rest, quiet and 
shade, together with an application of the atropia solution 
