This system is used for measuring close-range visual acuity using a new method. Patients are shown standard optotypes in random orientation. For this application a monitor unit was required, where the distance between the unit and the patient can be varied according to a special algorithm. Since it is a medical appliance, lubricant-freedom and esistance to disinfectants were basic pre-requisites for the materials used. A linear drive with drylin® polymer bearings was chosen, which adjusts the motor unit silently and smoothly.