| 摘要 |
<p>A progressive multi-focal lens is provided of the type having a distant viewing zone, a near viewing zone, and a progressive zone therebetween. The surface refractive power increases vertically from an upper portion of the lens to a lower portion as the line of sight scans from a distant view to a near view. Side zones are provided beside the progressive and near viewing zones. The side zones are spheric surfaces, with a dioptric refractive power in accordance with one embodiment being the arithmetic mean value of the refractive power of the near and distant viewing zones. This eliminates astigmatism problems in the side areas and permits normal side sight.</p> |
