ART. II.-A Treatise on Amaurosis and Amvrotic Affections. By EDWARD OCTAVIUS HOCKEN. 8vo. Pp. 359. London, 1840.

AMAUROSIS, from the variety of causes from which it may arise, and the frequent want of prominent symptoms to indicate the cause in each variety, has been long regarded as one of the most obscure diseases to which the eye is liable. Coming on frequently without any apparent cause, or produced by injury of parts apparently unconnected with the retina, whilst no marked changes are observed in the visible structures of the eye, it has been frequently regarded as a hopeless disease, and its treatment conducted empirically rather than on sound principles. Mr Hocken's treatise is therefore a valuable addition to the works already published on diseases of the eye; for in it the author not only shows an intimate knowledge of the works of previous writers, but he with great perspicuity defines the varieties of amaurosis, specifies the causes which may give rise to it, and the appropriate treatment for each of its forms. The whole is illustrated with numerous cases of the several varieties of the complaint. It forms a complete treatise on this disease, one very much wanted, and deserves a place in every medical library.

The arrangement which Mr Hocken follows appears well suited for the purpose, being founded on the anatomical characters. The treatise is divided into nine chapters. 1. On the anatomy and physiology of the visual nervous system. 2. The definition of, and general observations on amaurosis, including the symptoms, causes, diagnosis, prognosis, pathological anatomy, and treatment. 3. The classification of amaurosis; and on that form dependent on affections of the retina. 4. On amaurosis from affections of the 6. optic nerves. 5. On amaurosis from affections of the brain. On amaurosis from affections of the visual nervous system, brain, optic nerve, and retina. 7. On amaurosis from affections of the nervous trigeminus. 8. On congenital amaurosis. 9. On amaurotic and nervous affections.

It seems unnecessary to enter into any detail of what the author states regarding the anatomy and physiology of the visual nervous system, unless to say that he is sufficiently minute on all necessary points, with one single exception, which he has somehow overlooked, both in the anatomical details of structure, and in the physiology of the parts. We allude to the twisting of the optic nerves discovered by Professor Alison, and the explanation of the cause why images are seen upright, though represented as inverted on the bottom of the eye. For notices on both of these ubjects we refer to the fifty-second volume of this Journal,

(p. 530,) and to the thirteenth volume of the Transactions of the Royal Society of Edinburgh, (p. 472.)

On the disputed point of the decussation of the optic nerves at their commissure, the author does not throw any additional light; but a curious case, singularly illustrative of the opinion. of Mr Mayo, has lately been published by Dr O'Bryen of Dublin. * Mr Mayo stated as the result of his investigations, that a partial decussation or crossing of the fibres took place, the rest passing on uninterruptedly to the retina. In Dr O'Bryen's case, a tumour had destroyed the left optic nerve posterior to the commissure, indicated during life by complete loss of vision of the left eye, but only partial loss of that of the right eye.

Mr Hocken defines amaurosis to be "that imperfection or loss of vision which results either from the diminution or the entire loss of nervous sensibility, whether functional or organic, sympathetic or symptomatic." The symptoms he represents to consist in a peculiar appearance of blindness and want of expression, which is attributed to the inability of the patient to direct his eyes to the object he wishes to see. On this character Richter lays great stress as the best for ascertaining whether a person is feigning blindness. The pupil of the eye is found in every varying condition in amaurosis; most commonly the iris is dilated and immoveable, but when arising from chronic retinitis may be so much contracted as not to exhibit a pupil larger than the size of a small pin's head. Its mobility varies also; in general the iris moves sluggishly or not at all; in some cases, however, its sensibility appears to be increased. It is directed in all cases to cover the one eye when examining the other, as supposing only one eye is affected, the movements of the iris of the sound eye affect to a certain extent those of the diseased one. Strabismus is mentioned as being common when the disease is confined to one eye only. Oscillatory movements of the eye are also remarked in amaurosis. The eyeball itself is seen in two opposite states, either enlarged, prominent, firm, and resisting to the feel, or sunken, small, and unnaturally soft and yielding.

It is recommended in all cases to ascertain the peculiarities of the case, its exciting causes, its duration, the rapidity with which the symptoms increased, the age, idiosyncrasy, habits and employment of the patient. The forehead, face, and mouth are directed to be particularly examined for the purpose of ascertaining whether any of the branches of the fifth pair of nerves are irritated by a decayed tooth, or from being included in a cicatrix.

Under the head of subjective symptoms, the author mentions

• Dublin Journal of the Medical Sciences, January 1841, p. 1. See also the present number of this Journal.

the peculiarities of the imperfections of vision, the distortion of objects, the desire for strong mid-day light, the occasional intolerance of light, a symptom generally attributable to the presence of chronic retinitis, though it sometimes is independent of such a state. Double vision, or only seeing half of the objects, or in altered colours, together with various spectral illusions, as bright luminous sparks, flashes of light, muscæ volitantes, &c. are also noticed under this head.

Amaurosis is described as being complete or incomplete, incipient or confirmed. In the incipient stage some degree of vision is retained, and it is in this stage only that remedies are of any avail. When the blindness is complete from the first, the disease is often incurable under any treatment. In the confirmed stage the affection usually ceases to advance, and the sight is rarely entirely lost, a faint perception of light and darkness being still

retained.

The causes of amaurosis are various and often complicated. Mr Hocken mentions as causes of this disease, hereditary predisposition, sanguineous congestions, anæmia from excessive evacuations or other causes, over-exertion of the sight, sudden exposure of the eye to excessive light, blows on, or injuries of the head or eye, irritation of the fifth pair of nerves, various poisonous agents, disease of the abdominal viscera, and gouty or rheumatic diathesis.

The pathological conditions of the retina and choroid tunic which produce amaurosis are referred to, 1. Acute and chronic inflammation of the retina and choroid coats. 2. Organic changes the result of hyperæmia of these parts. 3. Pressure operating on the retina. 4. Injury of the retina from blows, wounds, &c. 5. Organic disease commencing in or implicating the retina. 6. Atony of the retina. The pathological conditions of the optic nerve connected with or producing amaurosis are enumerated under the following heads: 1. Inflammation and organic changes resulting therefrom in the optic nerve and its neurilema. 2. Malignant diseases or tumours seated on or near the optic nerve. 3. Injury of the optic nerve. 4. Pressure on the nerve from tumours, &c. The pathological conditions of the parts within the cranium which are capable of producing amaurosis are, 1. Acute and chronic encephalitis and their results. 2. Organic diseases. 3. Disordered circulation within the cranium, and apoplexy. 4. Injury, concus sion, fracture or depression. 5. An original defect or arrest of developement in some part of the brain. The pathological conditions of the visual nervous system productive of amaurosis are referred to two opposite conditions of the body, viz. plethora and anæmia, and also to the action of certain poisons, as belladonna, hyoscyamus, &c. Affections of the fifth pair of nerves or of its branches are likewise mentioned as causes of the disease.

The diagnosis of amaurosis is important from its liability to be confounded with incipient cataract or with glaucoma, but particularly as to cataract, for the treatment in the early stages of these two diseases is very different. Mr Hocken specifies the following as the most important diagnostic marks of these diseases. In incipient cataract, the vision is gradually impaired, objects are seen as if a mist or thin cloud intervened, which, as the lens becomes more opaque, gets thicker and thicker till objects are completely hid by it. In amaurosis the vision is either at once lost, or at least the loss of vision is sudden; objects appear distorted, imperfect, double, or covered with motes, flies, or black spots. In cataract, objects are best seen in an oblique direction, and in a dim light which allows the pupil to dilate. Amaurotic patients generally, though not always, see best straight forwards and in a bright light. The mobility of the iris is as great as in health in incipient cataract, but is greatly lost in amaurosis, in which disease there is a slight degree of strabismus, as also a loss of power of motion in the upper eyelid which never occurs in cataract. The vacant expression of the countenance is only met with in amaurosis. It is to be recollected, however, that the two diseases sometimes co-exist. The deep-seated greenish appearance of the pupil, and the altered colour of the iris serve to distinguish glaucoma.

As to the prognosis, it is stated, that the more recent the case is, and the less the injury of the sight, the greater is the chance of recovery. The prognosis is also favourable when the disease depends on debilitating causes. All cases, however, of long standing, or depending on affections of the brain, congenital imperfections of sight, or severe injury of the eye are unfavourable.

The morbid appearances, which are the cause or consequence of amaurosis, are described as consisting of thickening, opacity, and adhesion of the retina to the neighbouring coats; the formation of a shell of bone behind the retina which has been found converted into a white, firm, fibrous membrane. The retina itself, and ciliary bodies have been found converted into bone. The vessels of the choroid membrane and.retina have been seen in a varicose state. The medullary fibres of the retina have been observed to be entirely wanting in those who had been long amaurotic. The optic nerves have been noticed in various states of disease, as discoloured, flattened, atrophied, indurated, or softened; their medullary matter in a state of suppuration, or absorbed and replaced by fluid matters, whilst the fibres of the nerves were infiltrated with serum; cysts have been found in their neurilema, or their substance compressed with various tumours. All the morbid conditions of the brain or organic diseases of its membranes, or the compression and irritation arrising from disease or injury of the

cranial bones may give rise to amaurosis, in certain circumstances, and be therefore enumerated alongst with the other pathological appearances producing amaurosis.

The general treatment of amaurosis is detailed at considerable length. Venesection is recommended in all those cases which are attended with inflammatory action, or with local or general plethora; but it is condemned as highly injurious in all those forms which arise from, or are accompanied by debility, loss of tone of the minute arterial ramifications of the retina, the consequence of prolonged inflammatory action of that tunic, or where there is anæmia or atony of the retina. When it is necessary to abstract blood, it is directed to place the patient in the erect posture, and bleed to incipient syncope. Arteriotomy is justly condemned as an operation apt to be followed by troublesome or even dangerous consequences, and after all in nowise superior to the abstraction of blood from a vein, or by cupping at the nape of the neck or between the shoulders.

Purgative medicines in some form or other are recommended as applicable to nearly all forms of amaurosis. Mercury, however, is the remedy, which, of all others, is considered as the most generally applicable, and the most worthy of confidence in this disease. The object being to prevent the disorganization of the delicate nervous structure by its judicious, persevering, and effective use, calomel and opium in the proportion of two grains of the former, and one-half grain of the latter, is the form recommended in the acute form of amaurosis; whilst the blue pill or Plummer's pill, with or without a narcotic, as conium, is preferred for the chronic form.

This mineral is recommended to be given so as to produce a tender condition of the gums, as evidence of its constitutional action, and the system to be kept under its influence for some time; but if the amaurotic symptoms do not begin to give way when this state is once fully induced, the case is to be considered as hopeless.

Mr Hocken does not advert to a method of administering this mineral in small doses lately recommended by several practitioners both in Ireland and this country. The practice followed consists in dividing five grains of the blue pill mass or one grain of colomel into twelve parts, and giving one of these from every hour to every three hours, according to the urgency of the symptoms and the rapidity with which salivation was desired to be produced. By this mode of exhibition, the mercury does not act on the bowels, but is rapidly absorbed, and produces its peculiar physiological action. By the old plan it was difficult to induce salivation in less than two or three days at the very soonest, sometimes not at all;

VOL. LVI. NO. 148.

R