GB457977A - Improvements in or relating to sight-testing apparatus - Google Patents

Abstract

457,977. Sight - testing apparatus. PULZER, L. S., and STEARMAN, S. R., 45, Hatton Garden, London, and MAXWELL, E. H., 472, London Road, Croydon. June 5, 1935, No. 16395. [Class 97 (i)] In sight-testing apparatus comprising a plurality of rotatable batteries of lenses arranged in parallel planes, a higher power lens battery is arranged concentrically behind a lower power lens battery so as to be adjacent the patient and to occupy the same plane as would be occupied by spectacles of the patient, the location of the eye being effected by a suitably dimensioned eye-cup. An auxiliary rotatable battery may be arranged concentrically in front of the two other batteries, and a supplementary battery of lenses may be rotatably mounted eccentrically in front of the auxiliary battery. The high power battery 20 and the low power battery 22, mounted on the same axis 18, may be independently rotated in the field of view 24 by milled edges 21 and 23. The battery 20 may comprise spherical lenses of powers 0, - 3, -6,... -18, + 3, + 6, ... + 15 diopters, while the powers of the low power spherical lenses may be 0, -À25, .. -1, + À25 ... + 1À75 diopters..The values of the lenses occupying the field of view may be indicated through a slot 26. Concentric with the two lens batteries is a rotatable auxiliary battery 28 by means of which various devices may be placed in the field of view, such as an occluder, a lens for giving small variations in powers, a lens for retinoscopy, a prism for producing diplopia or two Maddox rods for muscle testing. A supplementary battery of lenses 38 is mounted on an axis 56 eccentric to the axis 18, and comprises two coaxial rotary lens holders 40, 42 each carrying non-spherical lenses, cylindrical lenses for example, rotatable into the field of view, indicating means being provided to identify the lenses occupying the field of view. An auxiliary detachable lens may be clamped in a holder 69 in the manner described in Specification 457,978. Reference has been directed by the Comptroller to U.S.A. Specification 1,804,691.