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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    tal plane, adduction and abduction would be associated with a tendency to converge the vertical meridians above, which would be prevented by the action of the inferior obhques. It is probable that the one or the other error of attachment of the internal and external recti is not uncommon. Thus it is seen that, with every contraction of the inferior recti, there must be an associated corrective contraction of the superior obhques; and that, with every action of the supe- rior recti, there is an accompanying and correcting action of the inferior obhques. Since we look down far more than we look up, the superior obHque muscles, in the same proportion, are made to do more work than the inferior obliques. Thus it is readily seen that the recti and obhque muscles, while opposing one another in action to a certain extent, work together in effecting binocular single vision, by keeping the two retinas so related that the images fall on corresponding parts. Plate I. represents a pair of eyes that are non-astigmatic; or, if astigmatism exists, the principal meridians are vertical and horizontal. These eyes are represented as looking at a rectangle. The Hne ef across the right eye is the horizon- tal meridian and the hne gh is the vertical meridian, while their point of intersection (5) is the macula. Similarly the line ef in the left eye represents the horizontal meridian, and gh the vertical meridian, their point of intersection (5) being the macula. The vertical meridian of the right and
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