Refraction and how to refract

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P. Blakiston's son, 1910 - 324 pages
 

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Page 55 - An eye in which the refracting surfaces (the anterior surface of the cornea and the anterior and posterior surfaces of the lens) and the intraocular media (the aqueous, crystalline, and vitreous humors) fulfil this condition is normal and is called emmetropic.
Page 84 - Amplitude of Convergence. — The far point of convergence is the point to which the visual lines are directed when convergence is at rest; the near point of convergence is the point to which the visual lines are directed with the maximum amount of convergence. The distance between the far point and the near point of convergence is the amplitude of convergence; it is expressed by the greatest number of meter angles of convergence of which the eyes are capable.
Page 307 - To accurately measure the distance from the center of one pupil to the center of the other...
Page iii - Refraction and How to Refract. Including Sections on Optics, Retinoscopy, the Fitting of Spectacles and Eye-glasses, etc. By JAMES THORINGTON, AM, MD, Adjunct Professor of Ophthalmology in the Philadelphia Polyclinic and College for Graduates in Medicine ; Assistant Surgeon at Wills...
Page 55 - SYNOPSIS OF CONTENTS. — I. Optics. II. The Eye ; The Standard Eye ; Cardinal Points ; Visual Angle ; Minimum Visual Angle ; Standard Acuteness of Vision ; Size of Retinal Image, Accommodation ; Mechanism of Accommodation ; Far and Near Point ; Determination of Distant Vision and Near Point ; Amplitude of Accommodation ; Convergence ; Angle Gamma ; Angle Alpha. III. Ophthalmoscope ; Direct and Indirect Method. IV. Emmetropia ; Hyperopia ; Myopia. V. Astigmatism or Curvature Ametropia ; Tests for...
Page 197 - Or strabismus may be defined as the condition in which the visual axis of one eye is deviated from the point of fixation. The eye which has the image of the object on its fovea is spoken of as the fixing eye, while the other eye is termed the squinting or deviating eye. The squinting eye does not always have normal visual acuity; and, in fact, correcting lenses will not always produce such a result. Convergent squint (con, "together...
Page 29 - A lens, therefore, has as many foci as there are imaginary points on the axial ray between the principal focus and infinity. When rays of light diverge from some point closer to a lens than its principal focus, they do not converge, but, after refraction, continue divergently; their focus now is negative or virtual, and is found by projecting these divergent rays back upon themselves to a point on the same si4e of the lens from which they appeared to come (see Fig.
Page 182 - Exotropia, a deviation of the visual axis outward. Hyperesophoria, a tendency of the visual axis of one eye to deviate upward and inward. Hyperesotropia, a deviation of the visual axis of one eye upward and inward. Hyperexophoria, a tendency of the visual axis of one eye upward and outward.
Page 1 - An optician is one skilled in optics, that branch of physical science which treats of the nature and properties of light, the laws of its modification by opaque and transparent bodies, and the phenomena of vision. He is one who deals in optical glasses and instruments. To merit the title of "optician...
Page iii - Diseases of the Eye. By EDWARD JACKSON, AM, MD, Professor of Diseases of the Eye in the Philadelphia Polyclinic and College for Graduates in Medicine ; and — Essentials of Diseases of the Nose and Throat.

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