have been of the same extent for a long time. It is all the same, then, whether they exist in one eye or both; even a partial paleness of the optic papilla does not alter the case. But we generally have a progressive atrophy when they are combined with marked lessening of the relative acuteness of vision in the remaining portions of the visual field, especially when the loss of vision decreases very irregularly in different directions towards the periphery. Treatment.—This must, of course, depend on the Treatment. cause of the amaurosis; in one case drugs, in another electricity, may be employed; and in all, as far as practicable, the state of the patient's general health should be carefully attended to. I may mention one point, Spectacles. and that is with reference to the use of spectacles; in all forms of amblyopia we may with advantage limit the patient to use the lowest convex glasses he can see with, and it may very possibly happen that subsequently he may be able to get on with a higher power, the sight improving under the use of convex glasses, which not only save a strain on the accommodation of the eye, but increase the clearness of letters and other small objects. HYALITIS. CHAPTER XII. DISEASES OF THE VITREOUS. Hyalitis-Musca-Opacity: syphilitic and anæmic- HYALITIS, OR INFLAMMATION OF THE VITREOUS, is said to have been induced by the presence of a foreign body, purposely passed through the vitreous chamber.* In instances of this kind, Donders describes changes occurring around the foreign substance, similar to those Simple form noticed in other parts of the body during inflammation. rare. Mostly complicated. Posterior hypopion. These pathological alterations may occasionally be traced when a foreign body, such as a piece of guncap, has accidentally passed into the vitreous. From proliferation of its connective-tissue cells the vitreous becomes hazy, the foreign body being enveloped in a greyish layer of opaque material, and branching out from this centre of irritation opaque streaks may be observed. Subsequently the connective tissue breaks down, and, the vitreous having become fluid, threadlike fibres may be seen floating about in it. These instances, however, must be very rare, for in the majority of cases the choroid and retina become involved, and it is then impossible to determine how far the changes observed in the vitreous are due to extraneous sources. I am disposed to believe that uncomplicated hyalitis seldom occurs in the human subject. Pus doubtless collects at times in the inferior part of the vitreous chamber, especially after the operation of reclination of the lens, forming what is called a posterior hypopion; but I am not disposed to admit of the existence of such a disease as idiopathic suppurative hyalitis; in fact, with Dr. H. Pagenstecher, I doubt the correctness of those who describe inflammatory changes * M. Wecker, "Maladies des Yeux," vol. ii. p. 282. as taking place in the vitreous. Dr. Pagenstecher has arrived at the conclusion that stecher's "1. Neither the gelatinous substance of the vitreous Pagen-, nor the elements contained in it are able, in consequence observations, of the influence of the irritation, which in other tissues produces the phenomena of inflammation, to produce lymphoid corpuscles by morphological changes. Hence it follows "2. That these must enter from the neighbouring organs. 3. The vitreous body appears to behave quite indifferently, even towards very violent irritations; or, more precisely expressed, it is not by them induced to call forth an accumulation of lymphoid corpuscles at the part influenced by the irritation-a phenomenon which we, in all organs susceptible of inflammation, see occur, even in shorter time, in consequence of the effect of similar irritation. "4. The vitreous body cannot, therefore, be con- Vitreous incapable of sidered as capable of inflammation, as we understand inflammait of every other organ; but every so-called inflamma- tion. tion affecting it can be only looked upon as secondary in consequence of the changes brought about in the neighbouring organs: also an irritation existing in the vitreous body only thereby can lead to inflammatory manifestations in, that has an influence exciting inflammation on, the vascular surrounding parts of the vitreous body. Simultaneously with these experiments I had abundant occasion to investigate extravasations of blood, and their changes in the vitreous body. In this I am able to corroborate the opinion adduced by Langhaus on the blood extravasations in general, namely, that the red blood-corpuscles are taken up by the contractile round cells, whilst it happened to me directly to observe this event in a fresh preparation of the vitreous of a rabbit."* VOLI MUSCE VOLITANTES.-Muscæ volitantes appear to MUSCA the patient under various forms, floating about in the TANTES. field of vision; they are often very annoying, but, unlike scotoma, they do not interfere with the perfection of vision. They appear to the patient to consist at times of * Brit. and For. Med.-Chir. Rev., vol. xlvi. p. 529, 1870. Motes in the field of vision. Shadows films in vitreous. slender rings, which seem to ascend from the lower part of the field of vision and then to fall down again. In other cases they take the form of pearly strings, which twist and twine about in all directions, or they may be seen as fine bands hovering about in the visual field. They are most distinctly seen when the patient looks at some clear bright object, as, for instance, at the sky or a white wall; in a dim light they are probably not visible. After overworking the eye they are very apparent, and also if the digestive organs are out of order. These various appearances are due to the presence of cells and of pale cells, or of granular fibres or shreds in the vitreous humour,* and the shadows which these cast on the retina are the direct cause of the muscæ volitantes noticed by the patient in the field of vision. In some few instances it appears that opaque globular spots, situated among the fibres of the lens, may, by intercepting the rays of light falling on the retina, produce the appearance of muscæ volitantes. Persons suffering from myopia are very apt to be troubled with muscæ, and they frequently cause such patients great anxiety. We may assure them of the harmless nature of these shadows, and by a tonic plan of treatment, and the employment of tinted glasses, they may hope to overcome the trouble from which they suffer. Of small consequence. How differing from scotoma. Muscæ, therefore, are by no means a symptom of any great consequence, and are often observed in persons whose eyes are otherwise healthy. The cells and filaments above described are too minute to be seen with the ophthalmoscope, and cannot therefore be mistaken for the opaque membranes floating about in a fluid vitreous, which may be detected without any difficulty at all. The muscæ differ from scotomata in that the latter follow the movements of the eye, as dark spots along the lines of a page in reading and writing, and do not float about as ill-defined shadows, an appearance characteristic of muscæ volitantes. Moreover, in the case of scotoma, the ophthalmoscope usually enables "Accommodation and Refraction of the Eye," by F. C. Donders, p. 199: Translated by Dr. Moore: New Sydenham Society. us to detect abnormalities in the retina, which account for the "dark spot" noticed by the patient. Treatment. It will often be found that cases of Treatment. muscæ depend on gastric derangement, or at any rate occur when the stomach or liver is out of order; and disorder. a little attention bestowed on these organs will do much correct OPACITIES OF THE VITREOUS.-Opacity of the vitre- OPACITY OF ous, as far as my experience goes, is most commonly VITREOUS. met with as a sequence of disease of the choroid, often Generally the result of either inherited or acquired syphilis. syphilitic. Excluding this class of cases, opacity of the vitreous is most commonly met with among short-sighted patients, or rather those suffering from sclero-choroiditis posterior. Another cause of opacity of the vitreous is extravasation of blood from rupture of one or more of the choroidal vessels. As an illustration of this affection, I may refer to the following history : Syphilitic Opacity.-Case 1.-D. Goodman, aged Case. twenty, a native of Australia. Until ten years of age his eyesight was perfectly good, and he learnt to read Hereditary and write with ease; but about this period his sight syphilis. became gradually impaired, so much so that he could Failure of no longer make out small print, and was punished for sight at supposed carelessness and inattention. The boy, find- age of ten. ing he was disbelieved and maltreated for no fault of his own, at length ran away in disgust, and worked his way up to Melbourne. He remained there for several years, employed as a messenger, his sight continuing in much the same state as when he left home. After wandering about the world, Goodman happened to find his way to Calcutta, and applied for aid at the Ophthalmic Hospital. He appeared to be in robust health, and was a strong, well-made lad. His eyeballs were of normal tension. With the left he could read No. 8 type at a distance of eight inches, but with the right he could not decipher the largest sized Evidence of print. On inspecting his teeth, I found that the inci- inherited sors were irregular and notched, and plainly told their syphilis. |