Physiologic optics : dioptrics of the eye, functions of the retina, ocular movements and binocular vision / by M. Tscherning ; authorized translation from the original French edition., specially revised and enlarged by the author by Carl Weiland.
- Marius Tscherning
- Date:
- 1904
Licence: In copyright
Credit: Physiologic optics : dioptrics of the eye, functions of the retina, ocular movements and binocular vision / by M. Tscherning ; authorized translation from the original French edition., specially revised and enlarged by the author by Carl Weiland. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
115/392 (page 87)
![the theory of the accommodative origin of myopia has, however, many believers, and I thinl< they are right ; but as the mechanism of accom- modation was scarcely known until recent times, it is not wonderful that the solution of the problem of myopia from near work was sought in vain. « 46. Selection of Spectacles. — Although myopia from near work is not to be considered as a true diseased condition of the eye, it always causes a disagreeable feeling which it is our duty to prevent as much as possible. As it is near work which produces myopia, young myopes must be made to work at as great a distance as possible; and, on account of the probable influence of accommodation, we must suppress the latter as much as possible, or annul it. — We are very frequently consulted on the question of glasses by parents who are worried at seeing their children become myopes. — If the myopia is low, under three dioptrics, we give correcting glasses for distant vision, and nothing for near vision, (i) rec- ommending the patient to be careful as to the distance of the book while reading. We place the normal distance for work at 33 centimeters. — If the myopia exceeds three dioptrics we give for near vision correcting glasses diminished by 3 D. For example, if the myopia is 6 D. we give 3 D. for near vision. For distant vision we may give correcting glasses or a supplementary glass to superimpose on the spectacles. — But, in giving concave glasses for near vision we must forcibly impress upon myopes the necessity of observing the minimum distance of 33 centi- meters when working; otherwise the glasses would be rather harmful by superinducing an effort of accommodation which might cause the myopia to increase. When the myopia exceeds 9 D., it becomes necessary to regard it as dangerous, and great care in the use of the eyes must be recommended. Generally it is preferable not to completely correct myopia, but only sufficiently so that the patient may not be too much annoyed in moving around. As the acuity is frequently diminished we can no longer insist on as great a distance for near work; thus we may give correcting glasses diminished by 4 to 5 D. for near work, which places the far point at 25 or 20 centimeters respectively. — The patient must be advised never to work with his head lowered; in the latter case where the dis- (1) [In the United States we prefer to let these myopic patients wear their glasses constantly, especially as these eyes are usually more or less astigmatic. The success of this method is proved by the careful in- vestigations of Dr. S. D. Rislcy. See his article on School Hygiene in the System of Disenses of the Eye by Norris and Oliver, Philadelphia, 1897.] —IK](https://iiif.wellcomecollection.org/image/b21466026_0115.jp2/full/800%2C/0/default.jpg)
