« SebelumnyaLanjutkan »
continuing for more than an hour. When a four-per-cent solution is used, the diminution of sensibility begins sometimes within the first minute, the anesthesia becomes absolute within ten minutes, and, if a second instillation be employed within two or three minutes after the first instillation, the anesthesia is complete within five or six minutes, as may be shown by rubbing the point of a probe over the cornea and conjunctiva. The instillation of neither of these solutions produces the slightest pain or discomfort, nor does it leave any lasting effects. There is no change produced in the appearance of the cornea or conjunctiva, nor is there any ophthalmoscopic evidence of an effect produced upon the intra-ocular circulation. The question whether the anesthesia extend more deeply and affect the deeper tissues of the eye, will be answered when we come to discuss its usefulness in ophthalmic surgery.
2. The Effects upon the Pupil.-The mydriatic effect of cocaine appears much more slowly than that of atropine, and it disappears more rapidly. The pupil usually begins to dilate within fifteen minutes after the instillation of a two-per-cent solution, and within eight minutes after the instillation of a four-per-cent solution. It increases slowly in size, and in some cases very slowly. It reaches its maximum in from thirty-five to forty-five minutes and then slowly diminishes, its contraction being much slower than its dilatation. In no case has the writer seen the pupil become as dilated under its use as it does from atropine, even when a four-per-cent solution has been used. In some cases, there was still a trace of dilatation on the day following the experiment. In one case, no dilatation of the pupil was produced after repeated instillations of the stronger solution, although atropine acted promptly on this patient.
3. The Effects upon the Accommodation.-The results here are, to the mind of the writer, still unsatisfactory, and they require further careful observation. The range of accommodation is shortened, and the near-point recedes from the eye, even when a two-per-cent solution is used. In the person of the writer, whose refraction is myopic, the shortening of the range of ac
commodation was equal to about D. 5, which came on within twenty minutes after one instillation of a four-per-cent solution. In most of the cases in which this effect was noted, the recession of the near-point began within twenty minutes after the instillation, continued to increase during fifteen or twenty minutes, and then almost immediately began to diminish, and, within an hour and a half, the range of accommodation was again normal. The effects of the drug are thus seen to be less marked and more transient on the ciliary muscle than on the iris. The degree to which the accommodation was affected varied very much in different patients. Hence, these observations upon the effects of cocaine on the accommodation need to be carefully repeated on a much larger number of patients before satisfactory conclusions on this head can be reached. In no case was there produced complete paralysis of accommodation.
We now come to the most important point for ophthalmic surgeons; viz., the usefulness of the drug as a local anesthetic in operations upon the eye. The points to be settled are two: 1. Are the anaesthetic effects of the drug, when dropped upon the cornea and into the conjunctival cul-de-sac, entirely superficial, involving only the surfaces of these membranes, or do they extend through the coats of the eyeball, merely requiring more time to produce their effects? 2. If the former be the case, can these effects be made to extend more deeply by injecting a few drops of the solution within the cornea or beneath the conjunctiva? The writer believes that the drug is absorbed, and that osmosis does occur, but very slowly and unsatisfactorily, even when a strong solution is employed and the anaesthetic effect upon the iris and the deeper tissues of the eye is but slightly marked. But the anesthesia of these highly sensitive membranes may be readily produced, in cases where it is necessary, by instilling a drop or two of the solution into the anterior chamber through the wound; and an operation for squint may be made absolutely painless by injecting a few drops through the conjunctival wound into the sheath of the tendon. The following résumé of a number of cases in which the cocaine was instilled, pre
liminary to operation, will give a clear idea of the extent to which it may be employed in ophthalmic surgery and of the limits of its usefulness:
I. The first case in which the writer employed the drug was a bad case of abscess of the cornea, with iritis and hypopyon, occurring in an enfeebled woman, aged fifty-four. Saemisch's operation of splitting the cornea was necessary, and, after two instillations of two drops of a two-per-cent solution, with an interval of ten minutes between them, the conjunctiva was seized with the forceps and the cornea split transversely just below the horizontal meridian, without causing the slightest pain.
II.-A case of kerato-iritis with hypopyon, occurring in a man aged thirty-five. After two instillations of a two-per-cent solution, with an interval of eight minutes between them, the anterior chamber was opened below by a broad paracentesis through the cornea, made with a lance-knife, and the pus was evacuated, without causing the patient any pain.
III.—A case of convergent squint with hypermetropia, occurring in a young girl aged seventeen, in which it was necessary to divide both internal recti muscles simultaneously. Two drops of a two-per-cent solution were instilled into each eye, and, after an interval of five minutes, two drops more were used. After a second interval of five minutes, the conjunctiva was seized over the insertion of the right internal rectus and divided painlessly; but the moment an attempt was made to open the sheath of the tendon, the patient winced and cried out, and expressions of pain continued for some time after the tendon was divided. In the left eye, after the conjunctiva was opened, two drops of the same solution were instilled beneath the conjunctiva, and, five minutes later, two drops more; and within ten minutes the internal rectus muscle of this eye was divided absolutely without pain.
IV. A case of leucoma corneæ, in a man aged eighteen, where it was necessary to perform an iridectomy for optical purposes. After the usual double instillation of a two-per-cent solution, there was complete anaesthesia of the cornea and conjunctiva, and the preliminary incision was made through the sclero-corneal margin, on the nasal side, without pain. The moment, however, the iris was seized with the forceps, the patient complained of pain and
continued to do so until after the operation was completed. This showed that the anesthetic effect of a two-per-cent solution, instilled in the manner described, had not at that time extended to the iris.
V.-A case of simple chronic glaucoma in one eye, with absolute glaucoma and cataract in the other eye, occurring in a woman aged fifty-five. A two-per-cent solution was instilled once into the first eye, and, after five minutes, a second time. In ten minutes after the first instillation, there was complete anæsthesia of the cornea. The preliminary incision was made in the limbus upward with a broad lance-knife. Then two drops of the same solution were dropped through the wound into the anterior chamber, and in ten minutes a broad iridectomy was completed, without the slightest sensation of pain being felt by the patient.
VI. A case of ordinary senile cataract, occurring in a man aged fifty-six, in whom a preliminary iridectomy with massage of the cornea, known as Förster's operation for maturing cataract, had previously been done. A two-per-cent solution was used in the ordinary manner, with complete anæsthesia of the cornea in ten minutes, and peripheral incision, quadrilateral capsulotomy, and extraction of the cataract were performed with ease and with entire absence of pain.
VII. A case of senile cataract, occurring in a man aged seventy-four, of excessively nervous temperament and of gouty constitution. In this case, a four-per-cent solution was used, and in twelve minutes the peripheral incision, iridectomy, capsulotomy, and extraction of the cataract were all done painlessly.
VIII. Another case of cataract, occurring in an old woman aged eighty-two. Here a preliminary iridectomy with massage of the cornea was done within fourteen minutes after the first instillation and within six minutes after the instillation of a four-percent solution within the anterior chamber.
IX.-A case of retention-cyst of the ocular conjunctiva, occurring in an elderly woman. The cyst was as large as a Lima-bean and hung down from the upper cul-de-sac over the eyeball. A twoper-cent solution was instilled twice, and within twelve minutes the cyst was slit up, its contents were evacuated with the spoon, and its inner surface was cauterized with tincture of iodine, all painlessly.
X.-A case of mucocele with stricture of the nasal duct of long standing, occurring in a woman aged thirty-four. A fourper-cent solution was instilled through the lachrymal punctum; and in eight minutes the canaliculus was slit, the sac opened, and its contents evacuated. Two drops of a four-per-cent solution were then dropped into the duct through the opening in the lachrymal sac, and in ten minutes the stricture was thoroughly divided with a Stilling's knife, and a large-sized Theobald's probe was introduced, all painlessly.
It may thus be seen that almost all the various operations done upon the eyeball, the inner surface of the eyelids, and on the tear-passages, may be performed painlessly under the anæsthetic influence of cocaine. The only operation on the eyeball in which it may not answer its purpose is that of enucleation; and even in such an operation, excessively painful as it is from the large number of the ciliary nerves involved, it may be possible, by a careful injection of a four-per-cent solution beneath the conjunctiva and within the fibrous capsule of the eyeball, to bring about anæsthesia even of these deeper nerves, and thus make the operation a painless one. Looked at even from the most unsatisfactory stand-point, and without the glamour of a very excusable enthusiasm, the drug is a most valuable addition to the resources of ophthalmic surgeons, and it relieves us, to a marked degree, from the thralldom of ether and chloroform. It may seem strange to the older members of the profession to hear such an expression as "relief from the thralldom of ether and chloroform," as scarcely forty years have elapsed since Morton first employed ether to relieve the pain of any operation. But, to the ophthalmic surgeon, the time necessarily occupied in complete etherization, the enormous engorgement of the ocular blood-vessels produced by the ether, the danger of the vomiting which may occur at any stage of an operation, and the fact that almost any apparatus for producing anæsthesia by inhalation is in the way of the operator upon the eye, are all such serious objections, that any degree of enthusiasm in the interests of a drug which certainly releases us from such a thralldom may