Abstract: A progressive addition lens includes a first fitting point, a near vision reference point and a first optical spherical power variation between the first fitting point and the near vision reference point. The lens further includes a second fitting point and a night vision reference point located on a same face of the lens, the night vision reference point being positioned on an eye gaze direction inclined by an upward eye gaze declination angle when the user wears the progressive addition lens mounted in a frame with a downward head declination angle opposite to the upward eye gaze declination angle without moving the frame relatively to the user's face, the progressive addition lens presenting a second optical spherical power variation between the second fitting point and the night vision reference point, the night vision reference point having a lower optical spherical power than the second fitting point.

Abstract: A progressive addition lens includes a first fitting point, a near vision reference point and a first optical spherical power variation between the first fitting point and the near vision reference point. The lens further includes a second fitting point and a night vision reference point located on a same face of the lens, the night vision reference point being positioned on an eye gaze direction inclined by an upward eye gaze declination angle when the user wears the progressive addition lens mounted in a frame with a downward head declination angle opposite to the upward eye gaze declination angle without moving the frame relatively to the user's face, the progressive addition lens presenting a second optical spherical power variation between the second fitting point and the night vision reference point, the night vision reference point having a lower optical spherical power than the second fitting point.

Abstract: A method for constructing a progressive varifocal lens having a far vision area, a near vision area and an intermediate progression area. the method comprises the steps of a) determining the x- and y-coordinates of a first point in the closed interval between the far vision reference point of the far vision area and the center point; b) determining the x and y coordinates of a second point as the near vision reference point of the near vision area; c) determining a mathematical function D(y) which obeys the following conditions: it contains the first and second points as local extrema and comprises exactly one point of inflection in the open interval between the two points; distributing the addition according to the said function along a principal meridian of progression connecting the first and second points; and d) forming the varifocal lens.

Abstract: A method for constructing a progressive varifocal lens having a far vision area, a near vision area and an intermediate progression area. the method comprises the steps of a) determining the x- and y-coordinates of a first point in the closed interval between the far vision reference point of the far vision area and the center point; b) determining the x and y coordinates of a second point as the near vision reference point of the near vision area; c) determining a mathematical function D(y) which obeys the following conditions: it contains the first and second points as local extrema and comprises exactly one point of inflection in the open interval between the two points; distributing the addition according to the said function along a principal meridian of progression connecting the first and second points; and d) forming the varifocal lens.