Local dioptric power matrix in a progressive addition lens

In this paper we use the formalism of the Dioptric Power Matrix to visualise and characterise the properties of a Progressive Addition Lens. For progressive addition lenses, the dioptric power matrix is point-dependent, and we have measured its elements over the lens surface by means of an automatic focimeter. We show the obtained contour plots corresponding to the matrix elements, and we compare them with the traditional sphere and cylinder graphs. Although the two representations give the same information, the advantages and disadvantages between them are analysed. The dioptric power matrix method turns out to be specially useful for the computation of prismatic effects along the lens surface.