Aspheric high positive power lenses and third order theory.

To correct third order (primary) oblique astigmatism of thin spectacle lenses outside an approximate lens power range of -22 D to +7 D, one surface must be aspherized. Aspherizing is of particular importance in the high positive power range used for the correction of aphakia. Graphs are presented showing the required front surface asphericities and power drops required to correct oblique astigmatism in this range. The results are a guide to the required asphericities in thick lenses.