An instrument that measures the power of a spectacle lens, or contact lens.
instrument for measuring focal length of a lens
• (n.) An assisting instrument for focusing an object in or before a camera.
Synonym for lensometer ... An instrument to measure the power and cylindrical axis of a spectacle lens. ... Synonym: focimeter, vertometer. ... Origin: Lens + G. Metron, measure ... (05 Mar 2000) ... 
Fo·cim'e·ter noun [ Focus + -meter .] (Photog.) An assisting instrument for focusing an object in or before a camera. Knight. 
Type: Term Pronunciation: fō-sim′ĕ-tĕr Synonyms: lensometer
focimeter A device for measuring the dioptic strength of a lens.