[ 328 J 
tho’ the catarafl appear fair, never to perform the ope- 
ration, but when the patient is fenfible of a glimmer- 
ing of light ; becaufe a total privation of fight argues 
fome other diforder of the eye. But the criterion is 
not infallible ; for it may happen, that a gutta fe - 
rena fhall prevail to a degree, that does not take away 
the fenfe of light, and yet prevents the distinction of 
objects: So that when a cataract is thus circum- 
stanced, the operation will be fruitlefs. 
It remains now to fpeak of the operation itfelf. 
In my former paper, after having deferibed the man- 
ner of making the incifion, I directed the operator to 
comprefs the inferior part of the globe of the eye with 
his thumb gently, till the cataract fhould be expell’d 
through the incifion of the cornea, upon the patient’s 
cheek ; and in tills method I have perform’d it upon 
Several Subjects. But remarking, that tho’, upon 
the evacuation of the aqueous humour, the cryftal- 
line readily advanced through the pupil into the an- 
terior chamber, yet that it required fome force to 
expel it from its membrane through the wound of 
the cornea, and in that action it fometimes fuddenly 
drew after it a portion of the vitreous humour, I 
changed my method, and no longer prefs’d the eye, 
when once the cryftalline was in the anterior cham- 
ber, but immediately fluck the point of my knife 
into the body of it, and extracted it contained in its 
capfula, without fpilling any of the vitreous humour. 
This new procefs, I fuppofe, will be found of 
considerable advantage, as it will, in a great meafure, 
remove the danger of evacuating the whole, or too 
much, of the vitreous^ humour : though it may be 
obferved, to the praife of this operation, that, con- 
trary 
