Please have a look at all the answers you got at matching the + character. In short do either of these:

$var1 = quotemeta $var1;   # do this before you use it in the regex

or

if ($line =~ /\Q$var1\E/m)
[download]

Either of these escape all regex metachars and should be considered mandatory if you want to avoid problems interpolating variables into regexes. PS Don't do both at the same time - it is either or!

cheers

tachyon

print quotemeta 'a+b';