The RT-8000 refractometer is made to measure the eyes with care. It measures the refractive error degree on the eyes as well as pupil distance and optical axis to name a few points. It is used for optometry sessions and will print out its results on the screen or with the printing button on a connected unit. An RS232 interface is used to make this link up to an appropriate printer. This unit may work with digital refraction with the data-output function ready for its use.