Low yellow index polymer compositions, polymerisable compositions and lenses using said compositions

A polymer composition obtained by polymerisation of a composition comprising:

• a component A comprising
• at least 50% by weight of a monomer or mixture of monomers having formula I:
• ##STR11## wherein R.sub.1 and R.sub.2,which may be identical or different, represent hydrogen or C.sub.1 -C.sub.6 alkyl, X represents:
• ##STR12## and m+n is an integer between 0 and 10, inclusive of 0 and 10;
• 0to 50% by weight of one or more mono- or poly-functional vinyl, acrylic or methacrylic comonomers (II);
• and
• a component B:
• comprising in a proportion of 0.5 to 15% by weight with respect to the weight of components (I) and (II), a compound having formula (III) ##STR13## wherein R.sub.3 and R.sub.4 represent hydrogen or one of radicals R.sub.3 and R.sub.4 represents hydrogen while the other forms with R.sub.7 a ring having 5 to 10 carbon atoms which may be substituted with one or more linear or branched C.sub.1 -C.sub.4 alkyl groups;
• and
• R.sub.5, R.sub.6 and R.sub.7 are selected independently of each other from hydrogen or C.sub.1 -C.sub.6 alkyl groups which may be substituted by one or more OH groups, and wherein the chain may be interrupted by one or more ether, ester or ketone groups, or R.sub.7 may form with one of radicals R.sub.3 or R.sub.4 a C.sub.5 -C.sub.10 ring which may be substituted by one or more linear or branched C.sub.1 -C.sub.4 alkyl groups.