Navigation:  Tools and Default Settings > Back Vertex Settings and Calculator

For precise calculations of achieved change in refraction, it is essential to report all sph and cyl values together with their vertex distances. You may specify default values which are filled in automatically each time you enter new refraction values. You may also change the vertex distance value individually (in case pre and postOP or individual postOP measurements are taken with different vertex distances.)

The vertex calculator can be used to convert plus and minus cylinder notation or to convert refractions from the spectacle plane to the  the corneal plane.