On unusual mobility of the iris : his own case / by John Paxton ; also, remarks on Dr. Paxton's case, with observations on the structure and action of the parts concerned in the focal adjustment of the eye, by Allen Thomson.

  • Thomson, Allen, 1809-1884.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: On unusual mobility of the iris : his own case / by John Paxton ; also, remarks on Dr. Paxton's case, with observations on the structure and action of the parts concerned in the focal adjustment of the eye, by Allen Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    dilated and inactive; but when one eye only is affected, the pupil of that eye as well as of the other may act in obedience to the reflex influence conveyed through the unaffected retina. The various modifications of form to which the pupil is subject, under the influence of different nerves, are not easily explained : thus, Valentin found that in rabbits the destruction of the inferior plexiform ganglion of the vagus nerve produces, along with con- traction, an oval form of the pupil, in which the upper part is smaller and angular; while, if the superior cervical ganglion of the sympathetic nerve has been destroyed, the contraction, which is fuller, is attended with the production of an oval form, with the small or angular end downwards. In these cases, touching the surface of the eye to remove fluid was always attended with a slight dilatation of the pupil. Ruete, in his learned treatise on the application of anatomy, physiology, and pathology to Ophthalmic Medicine, in R. Wag- ner’s Handworterbuch, vol. iii., part 2, gives reasons for regarding many of these influences as of a reflex character. He states that if the wires of a rotating electro-magnetic battery be applied to the eye of an animal in which the cerebral influence has been destroyed, but the sympathetic nerve left entire, dilatation of the pupil occurs; while in a living animal the same stimulus oc- casions contraction of the pupil. This he considers as analogous to the action of the rotating machine in causing the heart’s action to cease when applied to the vagus nerve; and he regards the trigeminus or fifth nerve as standing in the same relation to the sympathetic motor nerves of the iris, as the vagus does to the motor nerves of the heart; for, says he, just as we find with the heart, a slight stimulus of the rotating machine applied to par- ticular branches of the fifth nerve which join the ciliary ganglion causes dilation of the pupil, by action on the sympathetic nerves, but the full force of the machine applied to this nerve causes con- traction of the pupil, by acting on the oculo-motor nerve. In corroboration of this view, Ruete mentions more than one case in which slight injuries of the fifth nerve were attended with a dilated condition of the pupil; and he suggests farther, that in these modifications of the nervous influence of the sympathetic nerve may be found the explanation of the varying state of the pupil which accompanies different classes of diseases, the effect of the passions or states of the mind, and various other states of the economy. The remarkable property of belladonna or atropine, as also of hyoscyamus and stramonium, to dilate the pupil, which is a very serviceable assistance to the practical oculist, occasions much difficulty to the physiologist in attempting to give an explanation of the mode of action of these narcotics, in accordance with the known anatomical and physiological history of the structui’es involved in their operation. r.