Eyeglass Prescription Calculator

This works through the arithmetic hidden in a spectacle prescription. Transposition rewrites the same lens in plus cylinder or minus cylinder and shows the two meridian powers that stay the same either way; the full read out takes both eyes and a reading add and returns the near prescription, each spherical equivalent and the difference between the eyes; the third form adds two lenses at different axes through the power vector, which is how a trial prescription and an over refraction combine. Vertex distance is deliberately not here, because the site already has a page that does that conversion properly. This does not replace an eye examination and a prescription is not a lens order: the numbers on the card say nothing about pupillary distance, fitting heights, lens material or eye health.