Convert from spectacle Rx to CL power.
Obliquely Crossed Cylinders
Adds two spherocylindrical Rx's; also can determine a final CL Rx from a toric lens and a spherocylindrical over-refraction.
Size Difference (aniseikonia)
Using R/G glasses, click the half-circles to increase/decrease the size difference; can be measured horizontally, vertically, and/or obliquely.
Calculates and displays the approximate thickness of a [single-vision] lens given an Rx; can compare different refractive indices.
Gives a visual simulation of various options for correcting presbyopia.