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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    r 14 ACTION OF THE OBLIQUE MUSCLES this circular muscle remains quiet, or is in a slighter state of action. The parts in greatest action are supposed to coin- cide with the corneal meridian of least curvature. It is ar- gued that in this way lenticular astigmatism is produced, of the same kind as, but at right angles to, the corneal astigma- tism. If this be true, then in non-obhque myopic astigma- tism, distant seeing is not attended by sectional ciliary con- traction, since it would make vision worse and not better— distant vision in simple myopic astigmatism of i D. is better than when there is i D. of simple myopia. The object of all eye-strain is to improve vision; and when this cannot be effected, the strain is not instituted. In myopic astigmatism near vision would be greatly improved by sectional ciliary strain. In hypermetropic astigmatism sectional ciliary contrac- tion could sharpen both distant and near vision. Grant- ing that there may be, now and then, a case of masked hypermetropic astigmatism, which would point to the correctness of Martin's theory of sectional ciliary con- traction, the great mass of evidence gathered from daily ob- servations, by whomsoever made, goes to prove that there is no truth in his theory. In all cases of oblique astigmatism, unless the obHquity is in the same direction in the two eyes, and the astigmatism the same in kind and quantity, something must be done in
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