In any event, with conventional progressive power lenses, a wearer can select from lenses that emphasize far and near vision, far and intermediate vision, or offer a balanced performance. The type usually selec
In a pair of progressive multifocal ophthalmic lenses, in which each lens has an aspherical surface comprising a far vision portion, a near vision portion, an intermediate vision portion, and a prime
This gives the possible definitions of the optical power and astigmatism of the lens in the wearing conditions, which can be calculated as explained in the article by B. Bourdoncle et al, “Ray tracing through progressive ophthalmic lenses,” 1990 International Lens Design Conference, D T Moore...
A progressive surface is defined completely with the aid of a prescribed principal line and a prescribed distribution of the surface astigmatism. This also determines the surface power, as well as the properties in the position of use for spectacle lenses of type A, B and C. Proceeding in the...
Instead of making a concave aberration correcting progressive surface as explained hereinabove in the given example, one can manufacture lenses with aberration correcting progressive surfaces on the convex side of the lens, the concave side of the lens being made of a refractive surface of any known...
FIG. 3is a front view of the progressive-power lenses shown in FIG.1andFIG. 2; FIG. 4is a side view illustrating spectacle wear of a progressive-power lens; FIG. 5is a diagram illustrating transmission astigmatism and transmission average refractive power error (curvature of field) with spec...
The calculations are again performed with the thin lens approximation at every point on the sphere of vertices, as explained with reference to step 30. At the end of step 40, the eye movements and, possibly, head movements making it possible to correct these prismatic deviations have been dete...