Pointspread retinoscope

Details Pointspread retinoscope Pointspread retinoscope

1986-12-18

1988-07-19

Corbin, John K.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Objective type

351205, A61B 310

Patent

active

047580801

ABSTRACT:
A simple pointspread retinoscope and method of retinoscopy is described. The retinoscope consists of a variable radius shield mounted on a light source, to provide variable eccentricity between the axis of the light source and the edge of the shield. The observer points the retinoscope light source at the eye of a subject, and observes the retinal reflex over the edge of the shield. If a crescent is observed, the shield is rotated to a larger radius location and the procedure repeated. The highest numbered radial step at which a crescent of light appears in the pupil provides the eccentricity of the light source, and from this value, the value of the radius of the pupil, and the value of the distance between the shield and the pupil the defocus of the subject eye can be determined.

REFERENCES:
patent: 1631329 (1925-04-01), Patterson
patent: 2331591 (1940-09-01), Arnesen
patent: 2501438 (1947-03-01), Copeland
patent: 2715352 (1954-04-01), Jobe
patent: 3136839 (1964-06-01), Safir
patent: 3639041 (1972-02-01), Cornsweet
patent: 4432617 (1984-02-01), Itoh et al.

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