Calculate contact lens power from spectacle Rx.
Calculate spectacle Rx from a contact lens Rx.
Calculate lens power given two vertex distances.
Calculate what magnitude and orientation of oblique Fresnel prism.
Estimated residual astigmatism based off corneal Ks.
Convert plus cylinder prescriptions to minus cylinder prescriptions or vice-versa.
Calculate visual acuity from letter size and distance.
Calculate visual acuity from cy/cm and distance.