The OPD-Scan II ARK-10000 optical path difference (OPD) scanning system for human vision assessment has been unveiled by Nidek Co. Ltd., providing information on corneal topography, autorefraction, keratometry and pupillometry. The system uses the principles of skiascopic phase difference for refractive error map measurement. The retina is scanned with an IR light slit beam, and the reflected light is captured by photodetectors. With the Placido disk technology, the system captures the image of reflected rings of light from the cornea and analyzes the data points to plot the corneal contour, shape and refractive power. It provides various data maps to detail the overall visual quality of the eye. Optional software and a corneal navigator function are offered.