I'm not sure what you want. It's one of the following two.

1) Maybe you're looking for qr/.../.

$re = "\.";

foreach (qw( . a )) {
   print("$_ ", /$re/ ? "matches" : "doesn't match", " $re\n");
}

$re = qr/\./;

foreach (qw( . a )) {
   print("$_ ", /$re/ ? "matches" : "doesn't match", " $re\n");
}
[download]

outputs

. matches .
a matches .
. matches (?-xism:\.)
a doesn't match (?-xism:\.)
[download]

2) Maybe you're looking for \Q..\E (or quotemeta).

$var = '...';
$re = qr/abc\Q$var\Eghi/;

foreach (qw(
   abcdefghi
   abc...ghi
)) {
   print("$_ ", /$re/ ? "matches" : "doesn't match", "\n");
}
[download]

outputs

abcdefghi doesn't match
abc...ghi matches
[download]