42
© Rodenstock GmbH
Status: September 2023
6.4.4 Centering data
• Optional correction of dimensions in relation to different groove depths
• Determination of all centering data according to DIN EN ISO 13666, DIN EN ISO 8624 and DIN EN ISO
58208 (differentiation: disk plane and mount plane)
• Monocular centering point distance: Distance of the right or left centering point from the vertical axis of
symmetry of the spectacle frame, measured in the frame plane.
• Coordinates of the centering points: Distance the centering point has from the nasal vertical side or from
the horizontal side of the box system, measured in the lens plane
• Distance between the frames: Minimum distance between the panes in the frame plane
• Decentration of the centering point: Horizontal or vertical distance of the centering point from the vertical
or horizontal center line of the right or left box system, respectively, measured in the mount plane.
• Frame length and height: Distance between the horizontal and vertical sides of the rectangle
circumscribing the pane.
• Frame center distance: Distance between the geometric centers of the frame
6.5 Explanation of fitting parameters
The parameters determined are briefly explained below. The data are calculated according to DIN EN ISO 13666,
DIN EN ISO 8624 and DIN EN ISO 58208.
Individual parameters:
• Monocular pupil diameter R/L: Diameter of the visual hole enclosed by the iris through which light can
reach the interior of the eye and thus the retina.
• Monocular (Inter-)Pupillary distance R/L (PD): Distance between the frame center and the center of the
pupil when the eye is in primary position.
• Corneal vertex distance R/L (CVD): Distance between the back surface of the lens and the apex of the
cornea, measured in the direction of gaze perpendicular to the frame plane.
• Pantoscopic tilt R/L (PT): angle in the vertical plane between the optical axis of the lens and the fixation
line of the eye in primary position.
• Face form angle (FFA): Angle between the frame plane and the right or left lens plane.
Figure 6-10: Individual parameters
To Next Page