How to make Perl half/full width-insensitive regular expressions?

In Perl, /a/i matches both A and a, so I don't have to write /A|a/. What is the easy way to write /４|4/ ? Yes, I'm talking about

lang-sh
$ unicode ４ 4|grep U+
U+FF14 FULLWIDTH DIGIT FOUR
U+0034 DIGIT FOUR

Must I repeat each line,

if (/大茅埔段３２(７|８|９).地/ ||
        /大茅埔段32(7|8|9).地/)     {...}

or is there a better way? It's not that many characters, https://en.wikipedia.org/wiki/Halfwidth_and_Fullwidth_Forms_(Unicode_block) By the way, how to make

$ echo Ａ|perl -pwle 's/ａ/x/i'

match? (Both A's are wide.)