A focometer is a device that is used to measure the diopter adjustment of the lenses (in the case of digital focometer, even contact lenses). It helps to determine the value of other parameters of toric and multifocal lenses which are complementary to classical diopters: cylinder and axis for toric lenses, and the addition power for multifocal lenses. A focometer represents an integral part of the equipment of most eye-care clinics and ophthalmologists. The focometer can be either mechanical (older types) or digital. Digital focometers (automatic focometer) can be used to measure special attachments and contact lenses.