A lensmeter los yog lensometer, tseem hu ua focimeter lossis vertometer, yog ib qho khoom siv kho qhov muag. Nws yog tsuas yog siv los ntawm optometrists thiab opticians los xyuas qhov tseeb cov tshuaj nyob rau hauv ib tug ob peb tsom iav, kom zoo oriented thiab cim uncut lo ntsiab muag, thiab kom paub meej tias qhov tseeb mounting lo ntsiab muag nyob rau hauv spectacle thav ntawv.