Do you have any better idea to avoid the empty element ?

Yeah, don't use split to parse something that isn't a uniform list.

At a minimum, you could use the following:

my @var = $test =~ /\d+/g;
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A little more flexible:

my ($list) = $test =~ /\[ ( [^\]]* ) \]/x;
my @var = split /,/, $list;
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By the way, the following needlessly creates two variables that are never used (and issues a warning for having two variables with the same name):

my $empty;
my ($empty,@var) = ...;
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You want:

(undef, my @var) = ...;
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Update: Fixed pattern.