A variation that doesn't require foreknowledge of the backward step length:

c:\@Work\Perl\monks>perl -wMstrict -le
"$_ = '222,345,222,678,222,223,224,543,111,222';
 ;;
 while ( /22[2345],(\d\d\d)/g ) {
   print qq{after 22n: '$1'};
   pos = $-[1];
   }
"
after 22n: '345'
after 22n: '678'
after 22n: '223'
after 22n: '224'
after 22n: '543'
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