#!usr/bin/perl
use strict;
use warnings;

my $line;

while ($line =<DATA> and $line !~ /^\s*$/)
{
    print "do somehing with non blank line\n";
}  

__END__
Value of <HANDLE> construct can be "0"; test with defined() at C:\Users\mmtho\Documents\PerlProjects\Monks\test_myVar_inwhile_ver2.pl line 7.
do somehing with non blank line
do somehing with non blank line