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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    rows begin to shut and open hke the blades of a pair of scissors; and finally they are merged indefinitely mto one. What efforts are made by the eyes for the correction of astigmatism? In some forms of astigmatism, the cihary muscle labors to improve the state of vision, to sharpen the retinal image. When the rays of light come to the eye par- allel, no form of ciliary strain can improve the vision in my- opic astigmatism, simple or compound. For divergent rays in low degrees of myopic astigmatism, regular cihary con- traction may so act on the lens as to cause the focal interval to fall on the retina, whereby a sharper retinal image is formed. In hypermetropic astigmatism, the rays of light being either parallel or divergent, regular ciliary contraction can so act on the lens as to make the focal interval fall on the retina, and thus sharpen vision. In myopic astigmatism the best meridian being either in the horizontal or vertical, there can be no strain in distant seeing, for no kind of strain would improve the vision; but there may be cihary strain in near vision. In hypermetropic astigmatism, non-obhque, there is only cihary strain both for distant and near seeing. Sectional contraction of the ciliary muscle for the partial or complete correction of astigmatism has its advocates. Martin developed the theory. The ciliary muscle is sup- posed to act in two opposite sections; while the balance of
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