PUPIL. 



tixeciition. He introduced a (lender knife, about one line 

 from tlie margin of the cornea, through the coats of the 

 eye, iato tlic poilerior chamber, and puflied it through the 

 iris in the fituation of the clofed pupil, fo as to form in that 

 membrane a fmall longitudinal incifion. It is alleged that 

 ■ this operation of Chcfclden's has been repeatedly performed, 

 and for the moll part unfuccefsfully. According to the 

 obfervations ef Janin and Warner, the incifion did not di- 

 late, and became (hut up again foon after it had been made. 

 In one example, Janin was prevented from completing the 

 operation with accuracy, in confequeuce of hemorrhage 

 rendering the aqueous humour turbid. The plan of intro- 

 ducing the knife into the pofterior, inftead of the anterior 

 chamber, feems alfo to be difadvantageous ; for, in this lait 

 mode, the iris can be more eafily got at, and nothing is in- 

 jured except the infenfible cornea. On the other hand, in 

 Chefelden's method, all the coats of the eye, the lens and 

 its capfule, and the ciliary proccfTes, are all wounded. Be- 

 fides, as the point of the knife is concealed behind the iris, 

 one can never be certain that it is prccifely oppoiite the place 

 where the perforation of the iris ought to be made. 



It was the opinion of Janin, that when the incifion in the 

 iris was made in a parallel direclion to the radiated fibres of 

 this membrane, it always very foon doled again ; and, on 

 the contrary, that when it was made acrofs thefe fibres, it 

 not only dilated, but continued permanently open. He, 

 therefore, ufed to operate as follows : he firft divided the 

 lower half of the cornea, as in the operation for the cata- 

 raft ; he then pufhed a finely pointed pair of fcidors into 

 the iris, about one line from the lower edge of the cornea, 

 and the incifion was made in a perpendicular direction on the 

 infide of the pupil, without touching the pupil itfelf. The 

 cut ufually became dilated immediately, and remained open. 

 But care muft always be taken to make the wound in the 

 iris on the fide of the pupil next tlie inner canthus, as mak- 

 ing it on the oppofite fide might occafion fquinting. See 

 Janin's Memoires fur I'CEil. 



Wenzel's plan is more modern. The knife is introduced 

 into the cornea in the manner ufually done in the operation 

 for the cataraft ; but when it has approached within half a 

 line of the place of the clofed pupil, its point is to be de- 

 preffed to the depth of half a line through the iris. Three- 

 quarters of a line from this puniture, towards the inner 

 canthus, the point is to be elevated again ; and the incifion 

 of the cornea is then to be finifhed, as in operating for the 

 cataraft. In this way, a cut is made in the iris, refembling 

 on a fmall fcale the incifion on the cornea ; that is to fay, 

 it is of a femilunar fliape, and forms a fmall flap ; but it is 

 rarely fo fmooth and even as that in the cornea. The flap 

 is to be cut away with a fmall pair of fcifTors, fo that a 

 roundilh aperture, which is fure to remain open, is pro- 

 duced in the iris. When the flap cannot be got hold of, fo 

 as to admit of being removed with fcifTors, a fmall piece of 

 the iris is to be cut out. 



The method which we have next to take notice of, is 

 that propofed by the eminent Scarpa. He conceives, that 

 the artificial pupil may be molt eafily made, by detaching 

 a certain extent of the circumference of the iris, next the 

 nofe, from the ciliary ligament, by means of a couching 

 needle. Others objeft, however, that this mode is not 

 only difTicult, but that the aperture is hardly ever per- 

 manent. 



The lafl way of operating, of which it remains for us to 

 fpeak, is that recommended by Mr. Gibfon. This furgeon 

 begins by making a punAure in the cornea, with a broad 

 cornea knife, within a line of the fclerotica, to the extent 



of about three lines. All prcH'ure is now to be renioved 

 from the eye-ball, and the cornea knife gently withdrawn. 

 The confequcnce of this is, that a portion of the aqueous 

 humour efcapes, and the iris falls into contaft with the 

 opening in the cornea, and clofes it, like a valve. A flight 

 prefTure muft now be made upon the upper and inner part 

 of the eye-ball, and be gently increafed, or varied in direc- 

 tion, till the iris gradually protrudes, fo as to prcfent a bag 

 of the fize of a large pin's head. This protruded portion 

 muft be cut off with a pair of fine curved fcifibrs, and, at 

 the fame time, all prefTure is to be removed. The iris will 

 then recede within the eye, and the piece that has been re- 

 moved will leave an artificial pupil more or lefs circular. 



When the centre of the cornea is fo opaque, that the rayp 

 of light cannot enter the pupil, and the circumference of 

 that membrane is tranfparent, vifion may be materially im- 

 proved by removing a portion of the iris oppofite the un- 

 difeafed part of the cornea. 



There can be no doubt that, with refpeft to the com- 

 parative merit of the preceding modes of operating, Gib- 

 fon's plan ought in general to be preferred, as being nearer 

 and fafer than the others. Confult Sliarp's Trcatife of the 

 Operations ; Janin's Mem. fur I'CEil ; Wenzel on the Ca- 

 taraft ; Scarpa fuUe Malattie degli Occhi, capo 1 6 ; 

 Richter's Anfangfgrunde, &c. band. 3. kap. 9 ; Gibfon's 

 Pradt. Obf. on the Formation of an artificial Pupil, &c. 



Pupil, Preternatural Dilatation of. Tliis affettion, which 

 is termed mydriafis, is ufually a fymptom of fome other 

 difeafe, and is hardly ever an original complaint. It occurs 

 in very different degrees. Sometimes the pupil is fo confi- 

 derably expanded, that the iris canjufl be difcerned, like a 

 fmall fold at the inner circumference of the margin of the 

 cornea. In fome cafes, the pupil is totally immoveable ; in 

 others, it retains a certain degree of motion. Not unfre- 

 quently, it has loll its round fhape, and become of an ob- 

 long, or angular figure. In particular cafes, the afteftion 

 is only in one eye ; in the majority of initanccs, it takes 

 place in both. It is often accompanied with total blindnefs ; 

 occafionally, though lefs commonly, the patient retains the 

 faculty of feeing. In the latter cafe, the patient has an 

 averfion to the light, or is even quite blind in the day. He 

 is alfo ill conftant danger of being totally deprived of vifion 

 in a gradual way by the gutta ferena. (See Gutta Serena.) 

 To fome patients of this defcription, all objefls appear to be 

 fmaller and more diftant than they are in reality. The fol- 

 lowing are the difeafes of which mydriafis is commonly a 

 fymptom. i. Amaurofis, or the gutta ferena. Of this 

 complaint, however, it is not an infeparable and conftant 

 fymptom, the pupil fometimes retaining the power of mo- 

 tion, and being quite free from blemifh ; and in cafes where 

 it is dilated and motionlefs, it now and then recovers its na- 

 tural fize and moveablenefs, although the amaurofis con- 

 tinues unchanged. 2. The cataraft. Here mydriafis hap- 

 pens under two different ftates ; namely, either when the 

 cataraft is adherent to the iris ; or when the opaque cryftal- 

 line lens is preternaturally thick and large. In the firft cafe, 

 it ufually happens that the pupil is at the fame time incapa- 

 ble of motion, and irregular ; in the fecond, it fometimes 

 can move in a certain degree, and the iris is convex and prefled 

 forward toward the cornea. 3. Hydrophthalmia, or dropfy 

 of the eye. Here the dilatation of the pupil arifes imme- 

 diately from the diftended (late of the eye-ball, and with this 

 the diforder incrcafcs or fubfides. (See Hydrophthal- 

 mia.) 4. In patients who are troubled with worms ; who 

 are in fwoons, who are afflifled with hydrocephalus, apo- 

 plexy, or any comatofe difeafe, the pupils are in general pre- 

 ternaturally 



