Refraction of the eye : its diagnosis and the correction of its errors with a chapter on keratoscopy / by A. Stanford Morton.
- Morton, A. Stanford.
- Date:
- 1882
Licence: Public Domain Mark
Credit: Refraction of the eye : its diagnosis and the correction of its errors with a chapter on keratoscopy / by A. Stanford Morton. Source: Wellcome Collection.
42/76 page 30
![edg-e at n^/^/to that meridian of the eye parallel to which the mirror is rotated ; b, that it travels along- that meridian which is at right angles to the direction of its edge ; and, c, that it indicates the refractive condition of this last named meridian. If, for example, the mirror be rotated around its vertical meridian, from right to left or left to right, i.e. parallel to the horizontal meridian of the eye, the shadow will have its edg-e vertical] will travel in a horizontal direction across the area of the pupil; and will indicate the refraction of the horizontal meridian of the eye. For any g-iven meridian of the eye, the direction in which this shadow appears to move, i.e. whether with or against the mirror, depends upon, and furnishes the chief means of diag-nosing- the nature of, the refraction of that meridian. If the rays issuing from the observed eye do not cross before reaching- the observer, an erect image of the illumin- ated and shaded portion of the retina is obtained. This imag-e is seen to move in the direction actually taken by the illuminated area upon the retina, viz., opposite to that in which the mirror is rotated. This is the case in H., E. and low M. If, however, the issuing- rays cross before reaching- the observer, and form, between him and the patient, an in- verted aerial image of the illuminated and shaded portion of the fundus, then, since the illuminated area on the retina really moves against the mirror, the aerial image of the same will appear to move in a contary sense, i.e., in the same di- rection as, or with, the mirror. This appearance is met with in cases of M. of i D. {■^-^) and upwards: for if the](https://iiif.wellcomecollection.org/image/b20405728_0042.jp2/full/800%2C/0/default.jpg)
