On the anomalies of accommodation and refraction of the eyeNew Sydenham Society, 1864 - 635 pages |
Common terms and phrases
accom accuracy of vision accurately acuteness of vision amblyopia ametropia angle anomalies of refraction aphakia appears aqueous humour asthenopia astigmatism atrophy atropia auxiliary lens binocular vision calculation centre of motion chorioidea ciliary ciliary muscle connexion consequently convergence convex glasses cornea crystalline lens degrees of myopia determination deviation diminished dioptric system direction distance of distinct distinct vision diverging emmetropic eye exists farthest point focal distance focus fovea centralis Graefe h₂ horizontal hypermetropia hypermetropic eye layer magnitude meridian modation moreover muscles mydriasis myopes myopic eye nearest point negative glasses nodal point observed occurs ophthalmometer ophthalmoscope optic nerve paralysis point of distinct point of light power of accommodation presbyopia principal meridians principal points pupil radius of curvature range of accommodation reflected image refracting surface retina retinal images seen spectacles strabismus tension of accommodation tion vertical visual axis visual lines vitreous humour yellow spot
Popular passages
Page 344 - In this progressive extension progressive myopia is included, which is a true disease of the eye. " From what has here been said, it will easily be understood that high degrees of myopia are less likely to remain stationary than slight degrees are ; at a more advanced time of life they even continue to be developed, with increasing atrophy of the membranes. In youth, almost every myopia is progressive ; the increase is then often combined with symptoms of irritation. This is the critical period for...
Page 452 - These experiments prove that the points of the refracting meridians are not symmetrically arranged around one axis. The asymmetry is of such a nature that the focal distance is shorter in the vertical meridian than in the horizontal. In order, namely, to see a vertical stripe...
Page 259 - ... work, especially by artificial light, or in a gloomy place, the objects, after a short time, become indistinct and confused, and a feeling of fatigue and tension comes on in, and especially above, the eyes, necessitating a suspension of work. The person so affected now often involuntarily closes Ids eyes, and rubs his hand over the forehead and eyelids. After some moments' rest, he once more sees distinctly, but the same phenomena are again developed more rapidly than before.
Page 204 - Mackenzie informs us that few symptoms prove so alarming to persons of a nervous habit or constitution as Musca volitantes, and that they immediately suppose that they are about to lose their sight by cataract or amaurosis.
Page 343 - The distribution of near-sightedness, chiefly in the cultivated ranks, points directly to its principal cause, viz. : tension of the eyes for near objects. Respecting this fact there can be no doubt. "Three factors may here come under observation : 1. Pressure of the muscles on the eye-ball in strong convergence of the visual axes ; 2. Increased pressure of the fluids, resulting from accumulation of blood in the eye in stooping; 3. Congestive processes in the eye which tending to softening, give...
Page 329 - He who knows by experience how commonly H occurs, how necessary a knowledge of it is to the correct diagnosis of the various defects of the eye, and how deeply it affects the whole treatment of the oculist, will come to the sad conviction that an incredible number of patients have been tormented with all sorts of remedies, and have been given over to painful anxiety, who would have found immediate relief and deliverance in suitable spectacles.
Page 260 - If, on the contrary, he endeavours, notwithstanding the inconvenience which arises, by powerful exertion to continue close work, the symptoms progressively increase : the tension above the eyes gives place to actual pain, sometimes even slight redness and a flow of tears ensue, everything is diffused before the eyes, and the patient now no longer sees at first well, even at a distance. After too long-continued tension, he is obliged to refrain for a long time from any close work. It is remarkable...
Page 490 - has been sometimes led to the discovery of regular astigmatism of the cornea, and the direction of the chief meridians by using the mirror of the ophthalmoscope much in the same way as for slight degrees of conical cornea. The observation is more easy if the optic disc is in the line of sight and the pupil large. The mirror is to be held at...
Page 343 - Congestive processes in the eye which tending to softening, give rise to extension of the membranes. Now in connection with the causes mentioned, the injurious effect of fine work is, by imperfect illumination, still more increased. "To this it is to be ascribed that in schools where, by bad light, the pupils read bad print or write with pale ink, the foundation of nearsightedness is mainly laid which, in fact, is usually developed in these years.