Unless you need to do something else with all the matches at the end, I'm not sure why you'd save them all in an array. Just count. Example:

my( $x_lo, $x_hi ) = ( -180, -170 );
my( $y_lo, $y_hi ) = ( -130, -120 );

my $count = 0;

while (<>) {
  my( $x, $y ) = split;
  if ( $x >= $x_lo
    && $x <= $x_hi
    && $y >= $y_lo
    && $y <= $y_hi ) {
      $count++;
  }
}

print "$count matches.\n";
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If you actually needed the matches, it's simple enough to adapt the above to stick them on an array:

my( $x_lo, $x_hi ) = ( -180, -170 );
my( $y_lo, $y_hi ) = ( -130, -120 );

my @matches;

while (<>) {
  my( $x, $y ) = split;
  push @matches, [ $x, $y ]
    if $x >= $x_lo     # slighly different syntax,
    && $x <= $x_hi     # just to mix things up. :-)
    && $y >= $y_lo
    && $y <= $y_hi;
}

print scalar(@matches), " matches.\n";
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And here's a golfish version:

my( $x_lo, $x_hi ) = ( -180, -170 );
my( $y_lo, $y_hi ) = ( -130, -120 );

my @matches = 
  grep { $_->[0] >= $x_lo && $_->[0] <= $x_hi
      && $_->[1] >= $y_lo && $_->[1] <= $y_hi } 
  map [ split ], <>;
[download]