Hand-book of physiology (1892) (14762230201)

Identifier: handbookofphysio00bake (find matches)

Title: Hand-book of physiology

Year: 1892 (1890s)

Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed

Subjects: Physiology Human physiology

Publisher: London : John Murray

Contributing Library: Francis A. Countway Library of Medicine

Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

Text Appearing Before Image:

f the Ophthalmoscope, when a plane concaveglass is used. c. observers eye. The light reflected from any point, d, on retina of a,would naturally be focussed at e; if the lens b is used it would be focussed at i, inother words, at back of c. The image would be enlarged, as though of g, and would beinverted. (After McGregor Robertson.) power of accommodation is abolished, and the pupil is dilated. This willmaterially facilitate the examination ; but it is quite possible to observe allthe details to be presently described without the use of this drug. Theroom being now darkened, the observer seats himself in front of the personwhose eye he is about to examine, placing himself upon a somewhat higherlevel. A brilliant and steady light is placed close to the left ear of thepatient. The atropia having been put into the right eye only of the patient,this eye is examined. Taking the mirror in his right hand, and lookingthrough the central hole, the operator directs a beam of light into the eye

Text Appearing After Image:

Fig. 430.—Diagram to illustrate action of ophthalmoscope when a bi-convex glass is used.The fig. d on retina of a is under ordinary conditions focussed at/ and inverted. If thelens b be placed between eyes, the image h is seen by the eye c as an enlarged image.(After McGregor Robertson.) of the patient. A red glare, known as the reflex, is seen ; it is due to theillumination of the retina. The patient is then told to look at the littlefinger of the observers right hand as he holds the mirror; to effect this theeye is rotated somewhat inwards, and at the same time the reflex changesfrom red to a lighter colour, owing to the reflection from the optic disc.The observer now approximates the mirror, and with it his eye to the eye ofthe patient, taking care to keep the light fixed upon the pupil, so as not tolose the reflex. At a certain point, which varies with different eyes, but isusually when there is an interval of about two or three inches between theobserved and the observing eye,

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1892

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