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one evening at the time of sun-set that first the fringes of the clouds appeared red, and soon after the same colour was diffused over all the objects around her, and especially if the objects were white, as a sheet of paper, a pack of cards, or a lady's gown. This lasted the whole night; but in the morning her sight was again perfect. The same alternation of morbid and sound sight continued the whole time the lady was on the coast, which was three weeks, and for nearly as long after she left it; at which time it ceased suddenly and entirely of its own accord. Excess of light upon a delicate and irritable habit, appears to have been the cause of this singular affection. The retina was too strongly excited to throw off the impression easily—and that of the red rays of the descending sun, constituting the last impression communicated, remained after the sun himself had disappeared. The circle of action may be easily accounted for by an uniform return of the same cause.
The SECOND VARIETY of FALSE SIGHT, or that in which real objects appear changed in their natural qualities, is by Plenck denominated, in consequence of such change, metamorphopsia.
Sometimes the change exhibits ERROR OF FORM; and the objects appear too large, too small, cut in half, or distorted.
Sometimes ERROR OF MOTION: in consequence of which they seem to be dancing, nodding, or in rapid succession.
Sometimes ERROR OF NUMBER: and then they appear double, triple, or otherwise increased or multiplied ; constituting the diplopia of Sauvages and many other writers."
Sometimes ERROR OF COLOUR, in which case one hue is mistaken for another, as red for green, or green for yellow, or every hue appears alike. Examples of this imperfection are not unfrequent. Mr. Scott has given a singular instance of it in one of the volumes of the Philosophical Transactions *, and Dr. Priestly in anothert.
6 P. illusoria mutationis. Ocular transmutations. Metamorphopsia of Plenck. Error of form. Error of motion. Error of number. The diplopia of Sauvages. Error of colour.
* Vol. LXVIII. 1778. p. 611.
The last is especially worthy of notice as in some degree Gen. I. a family defect; and was communicated to Dr. Priestley
oy B P. illusoby Mr. Huddart of North America. Of five brothers ria mutaand two sisters, all adults, three of the former were affected with it in a greater or less degree, while the re- transmutamaining two and the two sisters possessed perfect vision.
Singular One of the brothers could form no idea whatever of
cd whatever OL example. colours, though he judged very accurately of the form and other qualities of objects; and hence he thought stockings were sufficiently distinguished by the name of stockings, and could not conceive the necessity of calling some red and others blue. He could perceive cherries on cherry-trees, but only distinguished them, even when red-ripe, from the surrounding leaves by their size and shape. One of the brothers appears to have had a faint sense of a few colours, but still a very imperfect notion : and upon the whole they seem to have possessed no other distinguishing power than that of light and shade, into which they resolved all the colours presented to them; so that dove and straw-coloured were regarded as white, and green, crimson, and purple, as black or dark. On looking at a rainbow one of them could distinguish it as consisting of stripes, but nothing more. Dr. Nicholl of Ludlow has published a case in the Further
illustrated, Medico-chirurgical Transactions *, of the same kind, in a case though the imperfection seems to have been confined to connected
with paropsis one or two colours alone. The patient could easily dis- longinqua. tinguish the green of the grass or the leaves of the trees, but, like those in Mr. Huddart's statement, he confounded with the green the red-fruit or flowers which happened to be intermixed with it. The false-sight in this case was also connected with paropsis longinqua; for the patient saw objects at a greater distance than other people, and more distinctly in the dark. The irids were here, also, grey, with a yellow tinge round the pupil. The causes of these varieties are not always assignable: Causes
often unas. many of them, however, are the same as have been point signable :
those of the * Transact. of the Medico-Chir. Soc. Vol. IX.
Gen. I. ed out under the variety of ocular spectres. Diplopia, or
errors of number, have often been occasioned by long ria muta exposure to severe cold, sometimes by local spasm, sometionis.
times by hydrocephalus * Baumer gives a case protransmuta- duced by a wrong position of the pupil +. Raghellini
another caused by a double pupil 1. In Lentin is a sinParticular
gularly complicated example of objects seen triply. diplopia or The chief diagnostic of many of these illusions is their error of number. mobility ll, which distinguishes them very decidedly from Triplopian. the fixt spots perceived in the eye, and which depend How far re- on an opacity of the lens, or a defective state of the mediable.
retina. They sometimes precede amaurosis or cataract, The chief pathogno. though not very often ; and when they have reached a mic, their
it certain point, cease to become more troublesome, or ramobility. In time cease mer, Irom napit, to be troublesom
ther, from habit, to be troublesome at all, and are little to be trouble- attended to : for if cataract or amaurosis do not soon folsome,
low, there is no reason for expecting either of them; a and do not
se to consolation of no small moment, as no certain remedy has any worse hitherto been discovered. complaint.
In other cases, and especially where the misaffection is not structural, but dependent upon an entonic or an atonic condition of the optic nerve, muscular fibres, or bloodvessels, benefit has been derived, in the first instance, from local bleeding, blisters, and sedatives; the sedatives being employed both generally and topically: and in the last instance by stimulant collyriums, and general tonics.
Many of these varieties of false-sight, and especially ocular spectres, are also found as symptoms in several species of dinus, syspasia, syncope, plethora, cephalitis, dyspepsy, and various fevers; some few of the filaments of the great sympathetic passing off, at its origin within the cavernous sinus to the orbit, and uniting with the lenticular ganglion [.
• Justi, Baldinger, N. Mag. Band. XI. p. 446. + Art. Hafn. I. Art. xxvii, # Lettera al S. Coechi sopra l'offesa della vista in una Donna. Venet. 1748, 1749.
§ Libr. 11. Obs. 20. Guthrie, Lectures, &c. ut suprà, p. 212.
q Cloquet, Traité d'Anatomie Description. Blork, Beschreisbung des fuene ster ponverpaares, &c. Leip. 1817.
DIMNESS OR ABOLITION OF SIGHT FROM OPACITY OP
THE CORNEA, OR SPOTS UPON ITS SURFACE.
The Latin term caligo sufficiently explains the na- Gen. I. ture of the disease, by importing “ dimness, darkness, SPEC. VI.
, Antiquated cloudiness, obscurity”. In old English this opacity, as colloquial 'well as the pterygium *, was denominated a “ web of the name eye”, from its apparently commencing in an obscurity of the hyaloid or choroid membrane, and giving the idea of a film spreading across the sight; whence Shakspeare in King Lear, “ This is the foul fiend Flibbertigibbet ; he gives the web, and the pin, squints the eye, and makes the hare-lip.” The pin is a variety of the synezesis, “ closed or contracted pupil”, or of one species of amaurosis, and will be noticed in its proper place.
The exciting or immediate cause of this disease is Exciting rarely discoverable, as for the most part it makes its ap
apo rarely disproach imperceptibly; it is often, however, a common coverable : consequence of old age. Judging from the last species,
mon consewe may place the usual proximate cause in a varicose or quence of congested state of the vessels of the cornea, or hyaloid tunic
Probable from debility, whence moreover the finer and more atte
proximate nuate parts of the secerned Auid are alone carried off, and cause. the denser and grosser left behind. Hence stimulants and
remedia). tonics, as blisters, weak solutions of brandy, camphor, alum, and nitrate of silver, are often found useful in the present day; as the saffron-coloured, or golden acrid juice
yet a com
or of the liver. Remedial
Gen. I. of the chelidonium majus, or greater celandine, diluted Spec. VII. with water or milk, was formerly. Paropsis Caligo. The disease is often accompanied with or preceded by Opake
congestion of the vessels of the head, and consequently a Chelidoni- stupid pain and heaviness : and in some cases there is um majus. reason to apprehend that this affection of the head is it
scłf the cause, or rather that an obstructed liver is the apparently caused by primary cause, from which the overloaded state of the congestion blood-vessels in the head originates. But where the pain in the head,
in the head is acute, and has followed instead of preceding the obscurity, the affected membrane has probably
yielded to inflammation. Leeches or cupping-glasses process in this case.
should be here freely applied in the first instance, as well
as brisk cathartics and mercurial alterants, and afterwards disease.
the stimulant plan just noticed. It is, however, generally
a tedious disease at best, and mostly incurable: and the Exemplified. author has at this moment a patient who has laboured
under the whole of the above symptoms for some months, though it is not long that he has had the care of her. She has tried local bleeding, purgatives, and at night an equal mixture of Plummer's and the mercurial pill; with the vapour of ether applied to the eyes three times a-day, and
apparently with advantage. . Pulsatilla Baron Stoerck strongly recommended an extract of the nigricans or
pasque-flower, pulsatilla nigricans, the anemone Pulsapasqueflower. tilla of Linnéus, for internal use; and from the success he
ascribed to it, the plant found its way into the Edinburgh Anemone Pharmacopæia. The anemone pratensis would probably pratensis.
answer as well. These plants in their recent state have very little smell ; but their taste is extremely acrid, and when chewed they erode the tongue and fauces. Other German practitioners, however, as Schmücker, Bergius, and Richter, have tried even the pulsatilla without success, though they have carried their doses to a larger ex
tent than Stoerck ventured upon. Small and frequently Tartarized repeated doses of tartarized antimony appear, upon so antimony many testimonies, to have been successful in various cases, in small doses. . that it is a remedy well worth a trial. Dr. Rowley used