Retinoscopy (or Shadow Test) in the Determination of Refraction at One Meter Distance: With the Plane MirrorP. Blakiston, 1912 - 71 pages |
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Retinoscopy Or Shadow Test - In the Determination of Refraction at One Meter ... James Thorington No preview available - 2010 |
Common terms and phrases
105 meridian aphakia appears to move area of light Argand burner ASYMMETRIC ASTIGMATISM axis 90 AXONOMETERS IN POSITION band of light beginner central illumination condition Conic Cornea convex lens correction cover chimney cycloplegic dark interspace dark room diameter diopter emergent rays emmetropic estimating the refraction eye under examination far-point focus give glass horizontal meridian hyperopia hyperopic eye illumination appears illustrations INDICATING SYMMETRIC ASTIGMATISM irregular astigmatism JAMES THORINGTON Lens for Study lens in front lenses light areas metal disc meter distance move opposite myopia myopic eye neutralizing lens objective method observer obtained OCULIST Ophthalmology ophthalmoscope patient patient's eye plane mirror point of reversal POSITION INDICATING ASYMMETRIC pupil pupillary area rate of movement rays of light recognized reflecting the light reflex refractive error retinoscopy round opening scissor movement screen seen shadow test shows sight-hole source of light sphere Spheric Aberration straight edge surgeon Thorington tilting the mirror trial-case writer
Popular passages
Page 15 - The patient must have his accommodation thoroughly relaxed •with a reliable cycloplegic, and should be seated comfortably, 1 meter distant, in front of the observer, with his vision steadily fixed on the observer's forehead, just above the mirror. Or...
Page 64 - October, 1896) is made of one-eighth inch asbestos, and of sufficient size to fit easily over the glass chimney of the Argand burner; attached to the asbestos by means of a metal clamp are two superimposed discs, which revolve independently of each other. The lower disc contains a piece of white porcelain, 30 mm. in diameter ; also four round openings, respectively 5, 10, 20, and 35 mm. in diameter. The upper disc contains a round 35 mm. opening, a round section of blue cobalt glass, a perforated...
Page 16 - ... but never directly into the mirror, as that would soon irritate and compel him to close his eye. In this way the patient avoids the strain of looking into the bright reflected light, and at the same time the macular region is refracted (see Fig.
Page 60 - Conic Cornea. — Reflecting the light into an eye that has such a condition, the observer is impressed at once with the bright central illumination that moves opposite to the movement of the mirror, the peripheral illumination moving with, unless perchance the margin should be myopic also, but of less degree. This form of illumination is seen in figure 33, showing the central illumination faintly separated by a shaded area or ring from the peripheral circle.
Page 32 - ... slight, and requires a weak lens for its correction. Form of Illumination. — A large, round illumination, while it may signify hyperopia or myopia alone, yet it does not preclude astigmatism in combination. When the illumination appears to move faster in one meridian than the meridian at right angles to it, astigmatism will be in the meridian of slow movement. If the retinal illumination is a band of light extending across the pupil, it signifies astigmatism. The width of the band of light...
Page 36 - ... in degrees to hold cylinders. Attached to the back of the upright frame by means of a hinge, is a chin rest, and a movable blinder, both of which swing to right or left as may be desired. The whole is mounted on a strong stand which can be raised or lowered to suit the requirements of each patient. The essential advantages of this skiascope are as follows: 1. It saves time and fatigue in changing lenses. 2. It is under the control of the operator, and indicates the lens in front of the sight...
Page 28 - ... from the patient's eye, as the case may be, find a point where the retinal illumination ceases to move. If this should be at two meters, the patient would have a myopia of 0.50 D. ; if at four meters, a myopia of 0.25 D.; if at one meter, a myopia of i.oo D., etc.
Page 49 - D., which is the amount of the cylinder required. After thus obtaining the result, the observer may, if so disposed, confirm it by placing the spherocylinder combination. Axonometer. — To find the exact axis subtended by the band of light while studying the retinal illumination when the meridian of least ametropia has been corrected, the writer has suggested a small instrument called an axonometer. (Fig. 21.) It consists of a black metal disc with a milled edge, i'/i mm.