1847.] PHYSIOLOGY. 55

fjavt Gifm'tr.

PERISCOPE.

PHYSIOLOGY.

Remarks on the Movement of the Iris. By Schur.

?ver since the law of reflex motion was discovered, the motor innervation of

1 e "is has been considered as falling chiefly, if not exclusively, under that

tj v' assumption derived probability from the correspondence

between

e amount of the stimulus of light and the extent of motion in the iris.

le c?ntraction of the iris at the moment of its being directed inwards and

pwards, a fact first observed by Miiller, was looked upon as a slight excep-

la?n f ^le ^W' an ev^ence ?f the iris being not entirely

excluded from the

of associated motion. Again, the dilatation and contraction of the pupil,

? e the intensity of light remains the same, according

as near or distant ob-

J cts are looked at, the pupillary movement partaking in the accommodating

P?wer of the eye, the contraction of the pupil subsequent to irritation of the

f_ "Junctiva, as also in neuralgic affections of different

facial nerves and other

c. ln favour of the associated character of the pupillary movement, were '

ntrely neglected. Lastly, the statement of older authorities regarding the

o. nuance Rt times of the motion of the pupil in amaurotic eyes, was ex-

P ained away by the supposition that the retina in such cases might still re-

am enough of sensibility for the excitation of reflex movement, or that the

Pwpu of a diseased eye might obey the stimulus of light falling on the retina

a sound eye. A case bearing on these points has recently occurred in the

Practice of Schur ; and to obviate all difficulties, he has given an exact ac-

?"?t ?f it. The following are its chief particulars :? he patient, forty years of age, was attacked

for the first time in 1836 by

general convulsions, the intervals between the attacks being gradually dimi-

islied till the autumn of 1041, when there hardly passed a day without

a

? The fit consisted in tonic contractions of the flexor muscles of the fore.

56 PHYSIOLOGY. [July

arm, hand, and fingers, of the muscles of the right side of the throat and

neck, in tetanic stiffness and transitory convulsion of the right leg, in quiver- ing movements of the facial muscles, in spastic closure of the rima glottidis with threatening of suffocation, and lastly, as happened thrice in the course of 1842, in a state of unconsciousness, with stertor, apparently the forerunner of apoplectic death. Before and during the ordinary attack, the patient expe- rienced a very intense aching, not increased by pressure, at the right side of the head below the parietal and temporal bones. In April 1841 the patient first observed an impairment of vision, the progress of the affection being so rapid as to pass into perfect blindness before the end of six months. At the time of examination the upper eyelid hung relaxed over the eye, covering the upper edge of the pupil, while it could hardly be elevated. The eye itself was fixed. The movements of the eyeballs, slow and difficult, were still in

correspondence with one another, with the exception of their convergent mo- tion, which was altogether lost. The pupils themselves appeared considerably dilated, of cloudy aspect, and showed no sign of motion whatever under direct or transmitted sunlight, or during the movements of the eyelids and eyeballs, consequent on the irritation of the conjunctiva, by means of a pen or other- wise. Nor had the attack any effect on the pupils or the eye-lids, the eye- balls alone being frequently rolled to the right side. As to the rest, the patient had incoherency of thought, his spirits impaired, his face had lost all expres- sion of intelligence ; the movements of mastication were slow and ungainly, the tongue was put out with difficulty, the articulation of words indistinct, the motion of the right extremities less energetic than those of the left side. As regarded the seat of this disease, the periodical convulsion of the right

side, without any cerebral symptoms whatever during the intermissions, with the exception of the paralysis of both optic nerves, suggested that it was in the motoreal cerebral apparatus of the left side, especially in the neighbour- hood of the thalamus opticus or chiasma. The nature of the disease next en-

gaged attention ; for though the existence of an adventitious formation would forbid any hope from treatment, the presence of a congestive, hemorrhagic, or inflammatory process, would render the prognosis less desperate. Schur in- clined to the latter alternative on the following grounds :?The first convulsive attack had occurred after powerful exertions continued for a few days, and the patient being of a plethoric constitution, was disposed to cerebral conges- tion ; and as the fits were followed by perfect intermissions, there was no ground for assuming the existence of a deep lesion of structure ; lastly, hy- peremic and hemorrhagic conditions are of far more frequent occurrence in the cerebrum than adventitious formations. He therefore prescribed venesec- tion to ten ounces, cupping between the shoulders every fortnight for three months, a plaster of tartar emetic to the neck, and a course of purgatives, be- ginning with more active cathartics, and passing from these to a mixture of rhubarb and flowers of arnica. After a few months of this treatment, the convulsive attacks, and the paralytic affections of the tongue, face, and extre- mities, disappeared, the eyes alone remaining in the former deplorable condition. About three years after this improvement, Schur was struck when examin-

ing the patient with the facility and rapidity of movement now exhibited in the upper eye-lids, while even the pupils appeared of far less magnitude, and again normal in their mobility. Notwithstanding this amelioration, the pa- tient could not distinguish light, nor yet were the motions of the pupils in any way influenced by its stimulus, or by irritation of the conjunctiva, the membrana Sclineideriana, or the lachrymal points. It was when the patient moved the eye-balls or eye-lids that motion of the pupils instantly took place, with this difference, that the movement of the eye-balls was commonly followed by uncertain and less lively action of the iris,?the motion con-

sisting sometimes in feeble dilatation, sometimes in feeble contraction ; whereas the opening of the upper eye-lids was accompanied constantly with a very considerable and vivacious contraction of the pupils. Whether the closing of the eve-lids was attended with dilatation of the pupils, Schur

1847.] PHYSIOLOGY. 57

did not succeed in discovering, though it is rendered probable by the circum- stance that, on the commencement of their opening, the pupils were always seen to pass from dilatation to contraction. Remarks.?The observation of Mfiller that the contraction of the rectus in-

terims and rectus superior is associated with the contraction of the pupil, has been already referred to. Now the case before us shows a greater extent of association in the motions of the pupils, namely, the motion of the pre- viously motionless pupils, in association with the action of the muscles, raising the eye-lid, as well as in that of certain muscles of the eye-ball. Thus the following conclusions result : 1st, Contemporaneously with the innervation of the levator palpebral superioris there takes place a motorial excitation of the circular fibres of the margo pupillaris : 2d, Contempora- neously with the innervation of the orbicularis palpebrarum there takes

place a motorial excitation of the longitudinal fibres of the iris, which

arising from the margo ciliaris of the iris, run to its pupillar border : 3d, The contraction of the recti and oblique muscles of the eye-ball gives rise to a more feeble and indefinite action of the pupillary fibres, the contraction being excited sometimes in the circular, sometimes in the longitudinal fibres of the pupillary curtain. Scliur considers the two first conclusions as demon- strated facts, corroborating their truth by observing that the protection afforded by the contraction of the pupil against the incident light is of far more use at the first opening of the eye than after the light has become diminished in its stimulus by being freelv absorbed. Of the third conclusion the evidence falls

niuch short of demonstration ; for on the one hand the action of the muscles of the eye-ball could not be considered as normal, the patient being unable to exercise these motions with exactness or to direct the eye-balls inwards; on the other hand, the rolling of the eye-balls being almost constantly accompanied with a feeble movement of the upper eye-lids, it could not be ascertained

whether the excitation of the pupillary fibres was in association with the action of the eye-ball or of the eye-lids. These remarks, however, must not be mis- taken for a denial of the reflectory motions excited by light in the healthy pupil, they go no further than to a restriction of the views hitherto prevalent. According to Schur the associated and reflectory movements are severally exerted as follows :?On opening the eye to moderate daylight, we observe in the first instant a quick and considerable contraction ot the pupil, this is fol- lowed in the next instant by a slight wavering of the diameter or an alternate contraction and dilatation of the pupil ; in the last instant when the iris is

come to repose, the diameter of the pupil is found to be greater than during the first instant, but less than during the dilatation in the second instant. ̂

In

the first instant the movement is an associated one, while in the second it is of

a reflectory character affected by and corresponding with the degree of the stimulus of light. It is therefore by this combination of mechanism that

the eye is protected against excessive light, and endowed with the power of

accommodating itself to the varying intensity of that stimulus.?Arcliiv.f. Physiol. Heilkunde, 1847. H. i., p. 37-48.

We fear these observations of Schur leave something still unexplained on this highly interesting point of Ophthalmic Physiology : what is here added to

our knowledge is a case of complete immobility of both pupils in which a

lesion of power in the third pair plainly accompanied the loss of sensibility in

the optic nerves, the recovery of the third pair after a time being followed by a restoration in part of the mobility of the pupils. Are we to conclude, then,

that, for complete immobility of the pupils in amaurosis, a direct affection ot

the third pair is necessary, as well as insensibility of the optic nerves . -in<^

it has long been known, as mentioned in Schur's statement (and some o o

readers may remember that it was known to Whytt1 a hundred years aD >

1 Whytt on Vital Motions, &c. 1750.

new series?$ro. XIII. JULY 1847. H

that the motion of the pupil depends on some other conditions besides the admission of light to the retina, the proper theoretical inference should all along have been, in amaurosis with complete immobility of the pupils, that the motor nerves of the iris have suffered a loss of direct power as well as of that which they exert when light falls on the retina. But to reconcile us to this inference we have still to discover why the common case in amaurosis should be that of complete immobility, while the less common case should be of partial mobility?that is, why in the common case there should be a direct affection of the third pair along with that of the optic nerves, while in the rarer case there should be a simple loss of power in the optic nerves. There is, however, this alternative. The liveliness of the motions of the pupil, as described by Scliur in the above case, at a time when the eyes were quite insensible to light, does not well accord with the belief of the principal source of its motions in health being the excitation of the retina by light,?but it is not improbable that a closer attention to those motions of the pupils which are independent of the stimulus of light, or which are not reflex, would show a greater variety as regards extent in different individuals than has hitherto been suspected, and it is not unreasonable to suppose that Schur's patient being of a very excitable habit was one in whom the motions of the iris, independently of light, had a maximum range. The accounts by practical writers of the state of the iris in amaurosis are often vague from the want of attention to the exact particulars in each case, and it cannot be doubted that where in complete blindness of both eyes the pupil has been thought to act on the admission of light, the direct motions, in excitable persons, have been mistaken for the reflex. If this view be well founded, the direct motions of the pupil in the complete amaurosis of ordinary temperaments pass unnoticed, while it is only in the very excitable that they become obvious enough for observation.