A lensmeter kapena lensometer, yomwe imadziwikanso kuti focimeter kapena vertometer, ndi chida cha ophthalmic. Amagwiritsidwa ntchito kwambiri ndi akatswiri a maso ndi akatswiri a maso kuti atsimikizire zolembedwa zolondola mu magalasi a maso, kuyang'ana bwino ndikulemba magalasi osadulidwa, ndikutsimikizira kuyika koyenera kwa magalasi mumafelemu owonera.