New truths in ophthalmology / as developed by G. C. Savage.

  • G. C. Savage
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: New truths in ophthalmology / as developed by G. C. Savage. Source: Wellcome Collection.

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    oblique astigmatism. The three axes of rotation are at right angles to one another, their point of intersection being the nodal point—the center of retinal curvature. The lateral recti muscles, if properly attached to the globe, will rotate it only on the perpendicular axis; the superior and inferior recti could not, if unopposed, effect the rotation of the eye on its transverse diameter, and hence would cause a form of double vision, in spite of the fact that they would keep the visual axes in the normal plane. In order to insure binocular single vision, other muscles are needed besides those that govern the visual axes; and these muscles are the obliques. If there were no such condition as astigmatism, or if the principal meridians in astigmatic eyes were always vertical and horizontal, there would be but one function for the oblique muscles, and that function would be the keeping of the naturally vertical meridians of the corneas parallel, and their study would be greatly simplified. The prime object of this paper, however, is to show that the obHques have another and more compHcated function to perform in many ■cases. Taking causes into consideration, we may say that the one function of the obliques is simple, while the other is complicated. The Simple Function of the Obliques is keeping the naturally vertical meridians parallel. The need for this exists in all eyes, whatever may be the state of refraction other than oblique astigmatism. Even in oblique
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