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

  • Thorington, James, 1858-1944.
Date:
1906
Catalogue details

Licence: In copyright

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

    30/92 (page 10)
    The room must be darkened—and the darker the better; all other sources of light except the one in use should be excluded. It must not be supposed from this that the room must have its walls and ceiling blackened; on the contrary, if the shades are drawn, the room will be sufficiently dark, though of course a room with walls painted black or draped in black felt would be best, as giving a greater contrast to the condition to be studied. The exclusion of other lights, or beams of light, must be insisted upon, as the Fig. 5.—The Author’s Light- screen, or Cover Chimney. {For a further description., see chap, vi.) principal use of the darkened room is to keep all light except the light in use out of the eye to be examined, and also not to have other lights reflected from the mirror. As the method of using the concave mirror with source of light (twenty or thirty mm. opening in screen) beyond its principal focus (usually over and beyond the patient’s Fig. 6.—The Author’s New Light-screen.