Apparatus for the subjective and objective determination of refr

Details Apparatus for the subjective and objective determination of refr Apparatus for the subjective and objective determination of refr

1981-11-24

1984-08-14

Bovernick, Rodney B.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Objective type

351237, A61B 310, A61B 302

Patent

active

044653484

ABSTRACT:
A compact apparatus for the subjective and objective determination of refraction of the eyes of a person. Two projection ray paths (6, 7), separated in space from each other, are provided, both ray paths containing systems (10, 11) for the continuous adjustment of spherical and astigmatic effects. Together with an optical telesystem (15) and the lenses of the eye they focus a test mark (3) on the retina of each of the eyes (18, 20) of the test subject. The light reflected by the retina passes via mirrors (14) into observation ray paths (21). They focus the retina and thus the test mark (3) in an image plane (30). The adjustment systems are displaced until the images of the test mark appear sharp in the image plane (30). After such an objective determination it is possible by actuating the same adjustment elements (10, 11) to adjust subjectively until the test subject sees the test mark with optimum sharpness. The projection ray paths are deflected via partially transmitting mirrors (17, 19) into the eyes of the test subject. The apparatus thus represents a free-view instrument. By inclining mirrors or the entire apparatus a near-distance vision examination is also possible.

REFERENCES:
patent: 3874774 (1975-04-01), Humphrey

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