Eyeball

“ The prevalence of myopia, the unsatisfactoriness of all explanations of its origin, and the futility of all methods of prevention, have led some writers of repute to the conclusion that the elongated eyeball is a natural physiological adaptation to the needs of civilization. ”

“ In this brutal contest the combatant was successful who could, with his thumb, press his opponent's eyeball out. Strange to say, little serious or permanently bad results followed such inhuman treatment of the eye. Von Langenbeck of Berlin mentions an instance of fracture of the superior maxilla, in which the eyeball was so much displaced as to lodge in the antrum of Highmore. Von Becker of Heidelberg reports the history of a case in which a blow from the horn of a cow dislocated the eye so far back in the orbit as to present the appearance of enucleation. ”

“ The eyeball is only slightly movable. The septum interorbital separates the two eyeballs laterally. As in mammals, the eyeball has three coats, which are from inside to outside, the retina, the choroid, and the sclera. ”

“ Whenever he came across any one with a peculiar eyeball, sometimes bright and clear, and at others covered with a filmy gauze, or a double pupil, ringed twice, or a larger eye on the left than on the right side, he would hold the thumb, fore and middle fingers in a peculiar manner, so as to ward off the evil effect of the eye. ”

“ Accommodation is brought about by a lengthening of the eyeball through the action of a pair of muscles on the outside. If the patient is able to look at a printed page without effort or strain, the eyeball will lengthen sufficiently to compensate for the loss of the lens. ”

“ When we understand, however, how the shape of the eyeball is controlled by the external muscles, and how it responds instantaneously to their action, it is easy to see that no refractive state, whether it is normal or abnormal, can be permanent. ”

“ This enables the lens to thicken on account of its own elastic force. To flatten the lens, the ciliary muscle relaxes, the elastic force of the eyeball resumes its tension on the suspensory ligament, and the membranous capsule resumes its pressure on the sides of the lens. This pressure, overcoming the elastic force of the lens, flattens it.
Movements of the Eyeballs.—In order that the light may enter the eyeballs to the best advantage, they must be moved in various directions. These movements are brought about through the action of six small muscles attached to each eyeball. ”

“ If the foreign body be sharp, as a piece of steel or flint is likely to be, it may be driven right into the eyeball.351 Seek a physician who will drop medicine into the eye to deaden the pain and then if it cannot be gently rubbed off the eyeball, a magnet will promptly remove it. ”

“ Consequently, when the eyeball becomes elongated from front to back, the convergence will be at a point in front of instead of upon, the retina. This is near-sight, as it may he recognized by object-tests or trial-glasses. But near-sight is sometimes simulated. This is caused by a spasmodic action of the muscle of accommodation. To determine absolutely, therefore, whether or not the eyeball has taken this abnormal shape, or whether the apparent near-sight is due to this spasmodic action of the focalizing muscle, the oculist must paralyze that muscle. ”

“ This organ is provided in the eye, which is not only itself capable of being moved in every direction, but is placed in the most movable part of the body, the head, which can be turned in almost a complete circle. The eyeball is spherical and lies in the cavity of the orbit upon a cushion of fat, where it has a large range of sight but is securely protected from injury by its bony surroundings. ”

“ The eyeball does not differ from that of an occidental, but the eye is less deeply set. The conspicuous peculiarity is that the upper eyelids are much heavier at the inner corners than at the outer, making the eyes apparently oblique ”

“ There is a leash of four muscles rising from a spot behind the exit of the optic nerve from the cranium to the upper, under, anterior, and posterior sides of the eyeball. These are the superior, inferior, anterior, and posterior recti. Running from the front of the orbit obliquely to the underside of the eyeball is the inferior oblique muscle. Corresponding to it above is a superior oblique. A lachrymal gland lies in the postero-inferior angle of the orbit, and a Handerian gland in the corresponding position in front. ”

“ The eyeball is moved by six muscles, which are described in the article Eye (Anatomy) . The relative attachments and the axes of rotation are shown in fig. 23.
The term visual field is given to the area intercepted by the extreme visual lines which pass through the centre of the pupil, the amount of dilatation of which determines its size. It follows the movements of the eye, and is displaced with it. Each point in the visual field has a corresponding point on the retina, but the portion, as already explained, which secures our attention is that falling on the yellow spot. ”

“ It appears as if here the judgment of direction could only arise from the excessive innervation of the rectus when the object is looked at. All the afferent feelings must be identical with those experienced when the eye is sound and the judgment is correct. The eyeball is rotated just 20o in the one case as in the other, the image falls on the same part of the retina, the pressures on the eyeball and the tensions of the skin and conjunctiva are identical. There is only one feeling which can vary, and lead us to our mistake. ”

“ I can now, six weeks after the beginning of the treatment, read ordinary print at twelve inches, and under favorable conditions can read diamond type at six inches or less. There has also been a considerable improvement in my field.
My progress has been slow, but it is sure, and I see no reason why it should not continue until I get a complete cure. I have spent many hours a day palming, and this, when it is successful, softens the eyeball and improves the sight very materially. I am also able to soften the eyeball simply by a thought—that is, by the memory of some object or incident. ”

“ In all the experiments all sources of error are believed to have been eliminated. They were all repeated many times and always with the same result. They seemed, therefore, to leave no room for doubt that neither the lens nor any muscle inside the eyeball has anything to do with accommodation, but that the process whereby the eye adjusts itself for vision at different distances is entirely controlled by the action of the muscles on the outside of the globe. ”

“ The increased tension is supposed to be due to an excess of fluid in the eyeball, and this is commonly attributed to an impeded outflow. The aqueous humor, which is secreted very rapidly, is supposed to escape at the angle formed by the junction of the iris with the cornea, and in glaucoma it is believed that the iris adheres to the cornea so that the angle is obstructed. ”

“ The observer was seated in an adjustable chair with chin and head rests, and a lateral sighting-tube by which the position of the eyeball could be vertically and horizontally aligned. The distance from the center of the eyeball to the surface of the screen opposite was so arranged that, neglecting the radial deflection, a displacement of 1 mm. in either direction was equal to a departure of one minute of arc from the plane of the eyes' horizon. ”

“ The muscular sensations of the eyeball signify this sort of visible spreadoutness, just as this visible spreadoutness may come in later experience to signify the 'real' bulks, distances, lengths and breadths known to touch and locomotion. [186] To the very end, however, in us seeing men, the quality, the nature, the sort of thing we mean by extensiveness, would seem to be the sort of feeling which our retinal stimulations bring. ”

“ This protrusion of the cartilage so as to cover the eye may be induced in the healthy eye by pressing the finger and thumb on the upper and lower lids, so as to cause retraction of the eyeball into the socket. When foreign bodies, such as sand, dust, and chaff, or other irritants, have fallen on the eyeball or eyelids it is similarly projected to push them off, their expulsion being further favored by a profuse flow of tears. ”

“ From the crystalline lens to the back of the eyeball, is a space more or less globular in form, containing a gelatinous diaphanous mass somewhat resembling white of egg in appearance, and called the vitreous humour.
Behind the vitreous humour, and immediately opposite the pupil and lens, is the most delicate and important of all the membranes of the eye, the retina, which serves as a screen whereon are received the images of the objects around us. This membrane is an expansion of the optic nerve N leading from the brain, and lines the whole of the interior of the eye. ”

“ If the eye be wounded, any part protruding beyond the sclerotic coat should be cut off with scissors; but the eye, however injured, should not be removed unless the ball be detached in every direction, or destroyed. The treatment should be strictly antiphlogistic, in order to prevent suppuration of the eyeball, which may in general be effected, if too much injury have not been done to it, and if the treatment be sufficiently decided and well continued. ”

“ If the front of our eyeballs had been flat, we should have had the power of seeing under water as clearly as in air; but instead of being flat, they are very convex, consequently our eye stamps a concave lens of high power into the water, and it is the seeing through this concave eyeglass which our eyeball makes for itself, that causes the indistinctness of our vision. ”

“ There is reason to believe that a degree of blindness, and even complete amaurosis, has been caused by wound of the eyebrow, the superciliary nerve having been contused, wounded, or otherwise injured; or the functions of the eyeball may be disturbed by concussion from injury. Paralysis, also, of the levator palpebræ superioris, or of several of the muscles belonging to the eyeball, may follow injury of the forehead and neighbouring parts, from either laceration or concussion of the nerves. ”

“ This invention exercises an influence not only on the peculiar branch of the oculist, but likewise on the broad field of medical investigation, seeing it affords an insight into the optic nerve, a direct process of the brain, and other structures, which, along with their analogies, were hidden from observation in the body.
The dimensions of the eyeball among strong-sighted individuals is more equal than you perhaps imagine. ”

“ When successful the eyeball will become harder in proportion to the degree of the strain; but, as it is very difficult to see, imagine, or remember, things imperfectly, all may not be able at first to demonstrate the facts.
GLAUCOMA: ITS CAUSE AND CURE By W. H. Bates, M. D.
GLAUCOMA is a condition in which the eyeball becomes abnormally hard, and theories as to its cause are endless. ”

“ When, therefore, persons who at one time appear to have hypermetropia, or myopia, appear at other times not to have them, or to have them in lesser degrees, it is not permissible to suppose that there has been a change in the shape of the eyeball. ”

“ VOLUNTARY PRODUCTION OF EYE TENSION A SAFEGUARD AGAINST GLAUCOMA It is a good thing to know how to increase the tension of the eyeball voluntarily, as this enables one to avoid not only the strain that produces glaucoma, but other kinds of strain also. ”

“ The arteries of the eyeball are all derived from the ophthalmic branch of the internal carotid, and consist of the retinal which enters the optic nerve far back in the orbit, the two long ciliaries, which run forward in the choroid and join the anterior ciliaries, from muscular branches of the ophthalmic, in the circulus iridis major round the margin of the iris, and the six to twelve short ciliaries which pierce the sclerotic round the optic nerve and supply the choroid and ciliary processes. ”

“ It is remarkable that movements of the eyeball itself, i.e. apart from movement of the lids, are not in the category of movements elicitable from the precentral gyrus, the “motor” cortex. They are found represented in a region farther forward, namely in front of the precentral gyrus altogether, and occupying a scattered set of points in the direction frontal from the areas for movements of arm and face. This frontal area yields on excitation conjugate movements of both eyeballs extremely like if not exactly similar to those yielded by excitation of the occipital (visual) region of the cortex. ”

“ It may grow from the outer angle, or even from either the superior or inferior hemisphere of the eyeball. The figure is invariably that of a triangle, with its base on the white of the eye and its apex more or less advanced over the cornea toward its center. ”