| 摘要 |
PURPOSE:To obtain a progressive multifocus lens which has a wide telephoto visual field regardless of degrees by setting astigmatism and mean refracting power below specific values over the entire surface of a specific refracting surface. CONSTITUTION:The astigmatism which is the cause of an out-of-focus image as to a progressive multifocus lens which is symmetrical between the right- and left-hand side is <=0.5D (dioptry) at the front surface through which a steady gaze is necessary and <=1.0D at the side part, such as the nose or ear side, through which a gaze is made by moving the eyeball. When a constant aberration curve 10 is suppressed below a limit line 9, there is no out-of-focus image formation at the nose side regardless of whether the lens is used for the right or left eye, so a comfortable lens is obtained. The angle 11 between a straight line perpendicular to the meridian and the limit constant aberration line 9 is set between 8 and 15 deg.. |
