An essay on the physiology of the iris : with a different view of its relations and sympathies from the one usually received : and an attempt to establish a new theory of the action of light upon the eye / by John Walker.

  • John Walker
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: An essay on the physiology of the iris : with a different view of its relations and sympathies from the one usually received : and an attempt to establish a new theory of the action of light upon the eye / by John Walker. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    18/20 page 16
    to the eyeball, which was followed by paralysis of both Retina and Iris, Would it be possible in such an experiment to avoid cutting or injuring the ciliary nerves, at the same time, surrounding, as they do, the optic nerve ? And what was the particular arrangement of the nerves of the eye, in the animal experimented upon. Upon a review of the whole of the facts and arguments adduced, it appears to result,—^Eirst, that the motions of the Iris depend, not upon impressions made on the Retina, but upon its own sensibility to light, as also upon its association with the muscles of the eyehds, through the medium of the lenticular ganglion:—Second, that these motions are for the purpose of adapting the eye to the perception of objects at different distances:—Third, that the Iris acts also in some measure as a defence to the more internal parts of the eye, as the palpebrae do to the external, forming, in fact, an internal eye- lid :—Fourth, that the external parts of the eye generally, as well as the Iris, are sensible to the stimulus of light :*—and Lastly, that the Retina is insensible to the ordinary impressions of light, as a stimulant; but that its functions may be impaired or destroyed by the more powerful concentration of light, as from the sun's rays, the coup de soleil, or from lightning, in the same manner as the brain and other parts of the nervous system are injured or paralyzed from the like causes. • During the last few days, I have witnessed a case of affection of the nerves of the face, which illustrates this question of the sensibility to light in a very satisfactory man- ner. The mouth find tongue were drawn to the left side—there was diminished sensibility of the right side of the face and mouth, with loss of taste : the eyelids of the right side could not be closed, and did not wink in concert witli the opposite : vision was perfect, but on placing this eye close to astrong gas light, no uneasiness was felt, and no attempt at winking followed. The sound eye could not bear the same light an instant. This case was seen also by my friend Dr. Kay, who observed all these phenomena. THE END. Trintcd by Wfbb and Simms, IManchester.
    digitised image 1
    digitised image 2
    digitised image 3