A lensometer, also known as a focimeter or vertometer, is a device used to measure the prescription of eyeglass or contact lenses. It determines the lens's optical power, helping optometrists verify the accuracy of a prescription and align lenses properly during the manufacturing of eyeglasses. lensometer is an indispensable tool in optometry and ophthalmology for verifying lens prescriptions, ensuring the accuracy of vision correction, and aiding in the proper fitting of lenses in glasses or contacts.