The present invention provides a process for the production of polymers with an optical position in diagram where refraction index n.sub.D is plotted against optical dispension v.sub.D expedient for an optical use by metathetic counterion exchange, wherein, in a polymer of the general formula: ##STR1## R.sub.1 and R.sub.2, which can be the same or different, are divalent organic radicals, R.sub.3 and R.sub.4, which can be the same or different, are monovalent organic radicals, n is a whole number greater than 2 and y is 0 or 1. R.sub.1, R.sub.2, R.sub.3, R.sub.4, y and n are so chosen that together they form a polymeric basic structure which promotes glass formation and prevents crystallisation, and X.sup.- is a halogen atom. The halogen ion is replaced by an equivalent of a mono- or polyvalent organic or inorganic counterion different from the halogen ion and suitable for the adjustment of the desired solid body properties.Because of their outstanding optical properties (high refractive index in conjunction with low optical dispersion), these polymers are very suitable for a great variety of uses in optics, for example for optical construction parts, such as Fresnel lenses and lightwave conductors, and as optical coatings.