I'm checking a variable for a regex that may or may not be there, using the following:

$var=~/(?:regex(catch_this)|)/; # My regex or nothing
I've also tried:
$var=~/(?:regex(catch_this)|.{0})/; #My regex or very literally nothin
+g
It always matches my regex when it looks like this:
$var=~/regex(catch_this)/;
[download]

And it always matches nothing when I use the former 2 examples.
Is there a way I can force it to look at the first expression rather than (As it appears to be doing) whichever comes first?

Regards,
spectre