484 
DEPARTMENT OF SURGERY. 
use of the glass, the smallest vessels cannot be seen and are 
therefore overlooked. The instrument necessary for the opera¬ 
tion is a Graefe knife. 
Operation .—The instruments used in periotomy are an eye- 
speculum, a sharp-pointed knife, small scissors and a small pair 
of dissecting or fixation forceps. The instruments and‘all other 
articles, such as sponges and bandages, must be well sterilized 
and the operation performed aseptically. The procedure, 
though comparatively simple, is a tedious one. A narrowband 
of the conjunctiva is dissected out from around the cornea and 
all the blood vessels going to it are resected ; the strip removed 
may vary in width from 3 to 4 mm. Heretofore, the greatest 
annoyance during the operation was the haemorrhage, but now, 
since the efficiency the extract of supra-renal capsules as a local 
haemostatic has been ascertained, haemorrhage is not such a dis¬ 
turbing factor. The blood supply to the seat of the operation 
is from the anterior and posterior conjunctival arteries {Fig. 
57-2), which form a plexus around the cornea {Fig. 57-4 ); 
these arteries anastomose with the anterior ciliary (j) and 
posterior ciliary arteries (/) in the scleral conjunctiva (0, 
which gives it very abundant blood supply. The haemostatic 
may be applied as a subconjunctival injection before the opera¬ 
tion is begun, which will make the conjunctiva bloodless. An¬ 
other method of applying the haemostatic is, to make the peri¬ 
pheral incision and treat it with the haemostatic before the inner 
incision is made and the strip of conjunctiva is removed ; this 
also enables the surgeon to do a bloodless operation. The 
patient must be cast or placed upon an operating table, a gen¬ 
eral anaesthetic administered, and then, if cast, placed in the 
most convenient position that will enable the operator to work 
without being hindered in any manner ; when this is accom¬ 
plished, the eyelids are retracted by the adjustment of the 
speculum ; the eyeball is fixed with the thumb and forefinger 
of the left hand, and with a small sharp-pointed knife, two in¬ 
cisions are made around the cornea about 3 or 4 mm. apart, 
and the conjunctiva between the incisions dissected out with 
a sharp knife and dissecting forceps. The part dissected out 
should not be more than 3 mm. inch) in width ; if the 
space between the two circular incisions is made too wide, it 
leaves a large cicatrix, which is always very noticeable, but if 
made very narrow, it leaves only a small mark in the conjunc¬ 
tiva, which is scarcely perceptible; and obliterates all vessels 
going to the cornea as well as when a wide strip is removed. 
