Retinoscopy (or shadow test) in the determination of refraction at one meter of distance, with the plane mirror / by James Thorington.

  • Thorington, James, 1858-1944.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: Retinoscopy (or shadow test) in the determination of refraction at one meter of distance, with the plane mirror / by James Thorington. Source: Wellcome Collection.

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    (i) It saves time and fatigue in changing lenses. (2) It is under the control of the operator, and indicates the lens in front of the sight-hole without his getting up. (3) The mechanism is simple and durable. (4) There are no shafts, uprights, or indicators to obstruct the view of the operator. (5) It is only under exceptional circumstances that it is necessary to use the disc containing the extra lenses. (6) There is only one indicator and one wheel to turn. While either the hand or the revolving disc is re- commended, yet the writer is partial to an accurately fitting trial-frame, using the lenses from the trial- case, which should be conveniently at hand. The following suggestions in the selection and use of the trial-frame are offered: The temples should rest easily on the ears, the nose-piece (bridge) to have a sufficiently long post to permit the eye-pieces to fit high and accurately over any pair of eyes, especially those of children, and have the corneae occupy the center of each eye-piece. Correct results can not be expected or quickly obtained unless the neutral- izing lenses be placed with their centers correspond- ing to corneal centers, and at the same time per- pendicular to the front of the eye.