A Treatise On Diseases Of The Eye; For The Use Of General Practitioners

Auteur:
Henry Clay Angell
ISBN:
9780217430623
ISBN10:
0217430627
Taal:
Engels
Bindwijze:
Paperback
Publicatiedatum:
08-02-2012
Geillustreerd:
Nee
Pagina's:
126 pagina's

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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. THE OPHTHALMOSCOPE. In order to see into the interior of an eye, it is necessary first of all that the interior should be lighted up. The old notion that an eye under certain nervous conditions becomes luminous from within is not correct. It can be illuminated only by light from without. The second condition necessary is, that, having thrown rays of light into the eye under examination, we should place our own eye in such a position relative to the one illuminated, as to catch the reflection of the rays of light which we have thrown in. These two conditions are absolutely necessary, and any further ones merely add to the convenience of examination or render our examination more accurate. With a bit of common window- glass we can fulfil these two conditions. Seat the patient in a darkened room with a lighted lamp by his side, the flame about on a level with the eye to be examined. With this fragment of glass held in front of the pupil and quite near the eye under examination, throw the rays of light from the lamp directly into his eye. This fulfils the first condition. The eye is illuminated. Now put your own eye behind the glass directly opposite that of the patient, and it will catch the return rays passing from his eye through the glass into yours, and you will see the entrance of the optic nerve, or optic disc as it is termed, and the vessels of the retina passing over and away from it. The fragment of glass is in reality an ophthalmoscope, and all ophthalmoscopes are merely modifications of this, and do not differ from it in principle. It has been found more convenient, however, to substitute for the plane glass a concave mirror with a small hole at its centre for the eye of the observer. A concave mirror reflects more light into the eye, and hence rende...


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Algemene informatie

Titel:
A Treatise On Diseases Of The Eye; For The Use Of General Practitioners
ISBN:
9780217430623
ISBN-10:
0217430627
Auteur:
Henry Clay Angell

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