VOL. XLVIII.] PHILOSOPHICAL TRAKSACTIONS. 417 



wound of the cornea, and was going to compress tlie eye, for the expulsion of 

 the cataract, he discovered, that from the disturbance he had given to the hu- 

 mours by the foregoing process, it was sunk almost as much as if it had been de- 

 pressed by a couching needle. He therefore left it in that situation, and the man 

 afterwards saw very well ; though the cataract remained visible something below 

 the pupil. Now in this instance the cataract had not passed through the pupil ; 

 and yet it was lacerated, so as to lose its circular form ; but whatever may be the 

 cause, he did not find, that the accident itself proved prejudicial to the sight. 

 He adds that when an incomplete gutta serena is complicated with the cataract, 

 the operation is of no avail. 



It remains now to speak of the operation itself. In his former paper, after 

 having described the manner of making the incision, he directed the operator to 

 compress the inferior part of the globe of the eye with his thumb gently, till the 

 cataract should be expelled through the incision of the cornea, on the patient's 

 cheek; and in this method he had performed it on several subjects. But re- 

 marking, that though on the evacuation of the aqueous humour, the crystalline 

 readily advanced through the pupil into the anterior chamber, yet that it required 

 some force to expel it from its membrane through the wound of the cornea, and 

 in that action it sometimes suddenly drew after it a portion of the vitreous hu- 

 mour, he changed his method, and no longer pressed the eye when once the 

 crystalline was in the anterior chamber, but immediately stuck the point of his 

 knife into the body of it, and extracted it contained in its capsula, without spilling 

 any of the vitreous humour. 



This new process, he supposes, would be found of considerable advantage, as 

 it would in a great measure remove the danger of evacuating the whole, or too 

 much of the vitreous humour : though it might be observed, to the praise of this 

 operation, that, contrary to expectation, a large quantity of this humour, per- 

 haps a 3d part, or more, had been sometimes discharged, without any bad con- 

 sequence. 



He supposes, that the great and sole benefit arising from this improvement, is 

 the easy separation of the crystalline from the bed of the vitreous humour, so 

 that none of this humour shall be evacuated. But perhaps it would also be ap- 

 proved of, as it would render unnecessary the measure prescribed by Mons. Da- 

 viel, of wounding the membrane of the crystalline, before we proceed to the ex- 

 traction of the crystalline itself: to which purpose he advises the flap of the 

 cornea to be suspended with a small spatula ; then, with a pointed cutting needle, 

 to wound the surface of the crystalline; after which, to introduce the same spa> 

 tula through the pupil, in order to detach the cataract from the iris, and then 

 proceed to the expulsion. 



He had here recited these processes of M. Daviel's operation, which are calcu- 



VOL. X. 3 H 



