Ophthalmic test apparatus having magnification compensation

Details Ophthalmic test apparatus having magnification compensation Ophthalmic test apparatus having magnification compensation

1980-10-31

1984-03-06

Evans, F. L.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Subjective type

A61B 302

Patent

active

044350520

ABSTRACT:
In apparatus for determining the refractive correction for a patient's eye, a plurality of similar test targets are presented to the patient simultaneously, with these test targets being viewed through different trial refractive corrections for the patient to choose between. Magnification differences produced by the different trial refractive corrections are compensated for by altering the size or shape of the different test targets, such that when magnified by the respective trial refractive correction, each test target appears of normal size and shape to the patient, not interfering with the patient's judgment of best clarity.

REFERENCES:
patent: 3240548 (1966-03-01), Biessels
patent: 3969020 (1976-07-01), Lynn et al.
patent: 4105302 (1978-08-01), Tate, Jr.
Asher, "A New Cross Cylinder Method", Oregon Optometrists, vol. 34, No. 4, pp. 9-11, (1967).

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