Treatise on the diseases of the eye : including the anatomy of the organ / by Carl Stellwag von Carion ; tr. from the 3rd German ed. and ed. by Charles E. Hackley and D.B. St. John Roosa ; with an appendix by the editors.

Karl Stellwag von Carion

Date:: 1870

Credit: Treatise on the diseases of the eye : including the anatomy of the organ / by Carl Stellwag von Carion ; tr. from the 3rd German ed. and ed. by Charles E. Hackley and D.B. St. John Roosa ; with an appendix by the editors. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

44/810 page 22

$The enlargement of the pnpil, which is caused by the true mydriatics. reacLes its maximum, that is, the iris is retracted to a narrow border, on]y when the agents are applied in sufficient quantity. The iris is completely immovable when this effect is attained; it does not react to alternations of light, or to changes in the converg- ence of the optic axes. The power of accommodation is also gi eatly limited. With a more powerful effect, the latter js even completely removed, and the refraction becomes a little less than corresponds to a normal relaxation of the accommodation. These effects last one or two days, according to circumstances, when the size of the pupil gradually becomes less, and its action is restored The paralysis of accommo- dation yields last of al1. It remains for days, decreasing steadily, after the pupil is restored to its normal size, and has regained its mobility. This impairment of the accommodation is evidence that the ciliary muscle, as weT as the muscles of the iris, are influenced by mydriatics. As an insurmountable proof of this, the fact may be adduced, that in isolated cases, after complete loss of the iris, very similar changes in the accommodation and refraction may be induced by the mydriatics. (Graefe.) These effects are, generally speaking, either the expression of a weakening or paralysis of the intraocular muscles, supplied by the third pair of nerves, or, very probably, the evidence of a direct excitement of those inner muscles of the eye which receive their nerve supplies from the cervical portion of the sympa- thetic. Indeed, the mydriatics enlarge the pupil to the maximum, where con- duction is completely interrupted in the third and fourth nerves, in fact, in all the cerebral nerves passing to the orbit. (Graefe.) These contractions are also more powerful than those which can be excited in the normal state, by external irritation, which state of things may be with some certainty referred to the radiate fibers of the iris. Mydriatics are useful, then, where we wish to secure a dilated pupil only, or a vigorous contraction of the muscles which accomplish this. Under some circum- stances, the reduction of the refraction of the dioptric apparatus is also useful. Besides, their paralyzing effect en spasm of the interior muscles supplied by the third pair is of value. Such spasms have been certainly observed, especially as a consequence of traumatic inflammations, and they have been relieved by mydriatics. The remarkable observation was at the same time made, that the function of accom- modation, which was impaired during the spasm, became free again, even before the pupil was dilated. (Graefe.) It seems, besides, as if these spasms appeared much more frequently than has been believed, or than could be proven. It is not improbable that they frequently accompany the severe forms of irritation of the sensitive ciliary nerves, which are very often observed in the various forms of keratitis, iritis, &c. The favorable effect of the mydriatics in those diseases is to be probably sought for in their anti- spasmodic effect. Mydriatics should be applied directly to the eye, if we wish their peculiar ac- tion to be certainly and thoroughly developed. They can then be absorbed by the conjunctiva and cornea. If this is not done, mydriasis either does not occur at all, or slowly and insufficiently, and very quickly disappears. In accordance with this, the direct application of _a mydriatic on one eye, does not cause the pupil to enlarge in both. Where mydriasis appears in the other, experience shows that it is to be attributed to an accidental application of the agent to that eye; a contraction of the pupil of the aye in which the mydriatic was not used has even been observed. This is probably to be ascribed$