Anomalies and Diseases of the Eye |
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Common terms and phrases
affected ametropia anomaly appearance aqueous humor astigmatism atrophy axis becomes blindness blood-vessels capsule cataract cause cent chamber choroid chronic ciliary body ciliary muscle circular color concave condition congenital conjunctiva convex glass cornea corrected crystalline lens dilated disc disease distance electro-cautery emmetropic entropion enucleated especially eyeball eyelid fibers fluid focus foreign body frequently fundus glands glaucoma hemorrhage hyperopia hyperopic hyperopic eye incision inflammation intraocular iridectomy iris iritis keratitis lacrymal layer lesion lids light limbus margin membrane mercury meridian Micro-photograph mirror mucous mydriasis mydriatic myopia nasal normal occasionally ocular opacity opaque operation ophthalmia ophthalmoscope optic nerve orbit pain palpebral pannus paralysis patient pigment portion posterior power of accommodation prism Prognosis pterygium pupil pupillary rays recti rectus refraction removed retina right eye sclera seen spot staphyloma strabismus suppurative surface sympathetic ophthalmia symptoms syphilis tion tissue trachoma treatment tumor ulcer usually vascular vision vitreous
Popular passages
Page 161 - He arrives at the following conclusions : — 1C ' 1. I think that the principal information gained in these examinations is that 22.4 per cent, of the school-children have some anomaly of refraction or accommodation which should be recognized and corrected early. " 2. That the hazel eyes, of all the colors, seem to be the ones most affected. " 3. That the light eyes, upon the whole, are less liable to be ametropic than the dark. " 4. That the females have a larger percentage of anomalies than males,...
Page 28 - A person is black-eyed, browneyed, or blue-eyed, according to the pigment in his iris. The Function of the Iris. The function of the iris is to regulate the amount of light that enters the eye. In the iris are circular muscle fibers, running around the pupil, and when these contract, they make the pupil smaller.
Page 2 - The angle of reflection is equal to the angle of incidence. 2. The incident and the reflected ray are both in the same plane, which is perpendicular to the reflecting surface. In Figure 4 let HO be an incident ray striking the polished surface AB at the point 0, and OH the perpendicular erected at that point. The ray RO is Fi(t 4. reflected in the direction OR', making the angle HOR
Page 161 - ... would never become manifest. The evil arising from work in the school-room is that these errors of, refraction are not perceived, and hence not corrected. If the teacher could be made to understand that the little...
Page 167 - They brought with them a full portion of all the riches of the past, in science, in art, in morals, religion, and literature. The Bible came with them. And it is not to be doubted, that to the free and universal reading of the Bible, in that age, men were much indebted for right views of civil liberty.
Page 21 - An object, therefore, placed between the principal focus and the lens will have its image on the same side of the lens as the object, but farther away.
Page 12 - The quotient found by dividing the sine of the angle of incidence by the sine of the angle of refraction, is called the index of refraction.
Page 44 - The circular fibres of the ciliary muscle exert a pressure upon the edge of the lens, by means of which the latter becomes thicker." 2. "The longitudinal fibres of the muscle cause an increase of tension in the vitreous humor, on account of which the posterior surface of the lens is prevented from shifting and the action of the peripheral pressure is chiefly confined to the anterior surface...
Page 4 - ... place from the concave side of a curved surface. We shall consider the case in which the reflecting surface is a segment of a sphere. The following definitions apply equally to concave and convex mirrors: The middle point of the mirror is called its vertex. The centre of the sphere, of which the mirror forms a part, is called the optical centre. The indefinite straight line through the optical centre and the vertex, is called the principal axis, or sometimes simply the axis. Any plane section...
Page 148 - ... its normal position begins really in very early life, about the age of ten years, and progresses gradually with increasing years. At forty it lies at eight inches, and at fifty at eleven or twelve inches. In the emmetrope no inconvenience is experienced before the age of forty or forty-five years. This change in the position of the near point is met with in all eyes, whether they are emmetropic, hyperopic, or myopic. In the emmetropic at fifty there is a slight amount of hyperopia, and at seventy...