use Modern::Perl;
use Data::Dump qw /dd/;

my @array_2d;

push @array_2d, do {chomp; [split ',']} while (<DATA>);

dd(@array_2d);

__DATA__
71,22,15,10,51
91,82,28,11,91
11,72,37,58,20
21,42,63,24,16
81,32,53,54,42

##</code><code>##

for my $row_ref (@array_2d) {
    for my $item (@$row_ref) {
        print "$item ";
    }
    print "\n";
}