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GEN. I. SPEC. VI. « P. illuso

ria phan

tasmatum. Ocular spectres.

6 P. illusoria mutationis. Ocular

transmuta

tions. Metamorphopsia of Plenck. Error of form.

Error of motion.

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; pia of Sau- constituting the diplopia of Sauvages and many other

Error of number.

vages.

Error of colour.

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 another+.

* Vol. LXVIII. 1778. p. 611.

† Id. LXVII. 1777. p. 260.

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GEN. I.

SPEC. VI.

P. illuso

tionis.

tions.

Singular

example.

The last is especially worthy of notice as in some degree a family defect; and was communicated to Dr. Priestley by Mr. Huddart of North America. Of five brothers ria mutaand two sisters, all adults, three of the former were af- Ocular fected with it in a greater or less degree, while the re- transmutamaining two and the two sisters possessed perfect vision. One of the brothers could form no idea whatever of 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 Medico-chirurgical Transactions*, of the same kind, though the imperfection seems to have been confined to one or two colours alone. The patient could easily distinguish 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: many of them, however, are the same as have been point

* Transact. of the Medico-Chir. Soc. Vol. IX.

illustrated,

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Further
in a case
connected
with paropsis
longinqua.

Causes signable:

often unas

sometimes those of the preceding varieties.

GEN. I. SPEC. VI.

6 P. illuso

ria mutationis. Ocular

transmutations.

Particular causes of

diplopia or error of

number.

How far re

mediable.

The chief

ed out under the variety of ocular spectres. Diplopia, or errors of number, have often been occasioned by long exposure to severe cold, sometimes by local spasm, sometimes by hydrocephalus *. Baumer gives a case produced by a wrong position of the pupil †. Raghellini another caused by a double pupil ‡. In Lentin is a singularly complicated example of objects seen triply §.

The chief diagnostic of many of these illusions is their mobility, which distinguishes them very decidedly from Triplopian. the fixt spots perceived in the eye, and which depend on an opacity of the lens, or a defective state of the retina. They sometimes precede amaurosis or cataract, pathogno- though not very often; and when they have reached a certain point, cease to become more troublesome, or rather, from habit, to be troublesome at all, and are little attended to: for if cataract or amaurosis do not soon follow, there is no reason for expecting either of them; a consolation of no small moment, as no certain remedy has hitherto been discovered.

mic, their mobility.

In time cease to be trouble

some,

and do not predispose to any worse 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. x1. p. 446.

Art. Hafn. 1. 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.

¶ Cloquet, Traité d'Anatomie Description. Blork, Beschreisbung des fuen ster nonverpaares, &c. Leip. 1817.

SPECIES VII.

PAROPSIS CALIGO.

Opake Cornea.

DIMNESS OR ABOLITION OF SIGHT FROM OPACITY OF
THE CORNEA, OR SPOTS UPON ITS SURFACE.

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THE Latin term CALIGO sufficiently explains the nature of the disease, by importing "dimness, darkness, cloudiness, obscurity". In old English this opacity, as ́well as the pterygium was denominated a "web of the 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.

GEN. I.

SPEC. VII.. Antiquated colloquial name web

eye.

cause

yet a com

mon conse

quence of

old age.

Probable

The exciting or immediate cause of this disease is Exciting rarely discoverable, as for the most part it makes its ap- rarely disproach imperceptibly; it is often, however, a common coverable: consequence of old age. Judging from the last species, we may place the usual proximate cause in a varicose or congested state of the vessels of the cornea, or hyaloid tunic from debility, whence moreover the finer and more atte- proximate nuate parts of the secerned fluid are alone carried off, and cause. the denser and grosser left behind. Hence stimulants and 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

* Vol. 11. Cl. 11. Ord. 11. Sp. 1.

How far

remedial.

GEN. I. SPEC. VII.

Paropsis

Caligo.
Opake

cornea.

Chelidoni

um majus. Sometimes apparently caused by congestion in the head, or of the liver.

Remedial process in this case.

of the chelidonium majus, or greater celandine, diluted with water or milk, was formerly.

:

The disease is often accompanied with or preceded by congestion of the vessels of the head, and consequently a stupid pain and heaviness and in some cases there is reason to apprehend that this affection of the head is itsclf the cause, or rather that an obstructed liver is the primary cause, from which the overloaded state of the blood-vessels in the head originates. But where the pain 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 should be here freely applied in the first instance, as well as brisk cathartics and mercurial alterants, and afterwards 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.

A tedious disease.

Pulsatilla

pasque

flower.

Anemone pratensis.

Baron Stoerck strongly recommended an extract of the nigricans or pasque-flower, pulsatilla nigricans, the anemone Pulsatilla of Linnéus, for internal use; and from the success he ascribed to it, the plant found its way into the Edinburgh Pharmacopoeia. The anemone pratensis would probably 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 extent than Stoerck ventured upon. Small and frequently repeated doses of tartarized antimony appear, upon so many testimonies, to have been successful in various cases, that it is a remedy well worth a trial. Dr. Rowley used

Tartarized antimony

in small doses.

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