There's a built in pragma called constant which I'd probably reach for before trying to do something clever with typeglobs:

$ perl -Mstrict -Mwarnings -le '
    use constant MYVAR => 3.14159;
    print MYVAR;
    use constant PI => 4 * atan2(1, 1);
    print PI;
'
3.14159
3.14159265358979
[download]

However, if you're stuck with the typeglob, I'd take a pragmatic approach and pick the one which involves the least typing (i.e. ${*myVar}).

$ perl -Mstrict -Mwarnings -le '
    *myVar = \3.14159;
    print ${*myVar};
    print ${*myVar{SCALAR}};
    print $main::myVar;
'
3.14159
3.14159
3.14159
[download]