PHP glob() to list file that doesn't start with underscore?

The standard glob() function usage is like

$dir = glob("*.txt");
foreach ($dir as $filename) {
    echo "$filename size " . filesize($filename) . "\n";
}

using * as wildcard, but is there a way to negate it to ignore any file that starts with underscore like _something.txt? I am trying to avoid using preg_match() like

$dir = glob("*.txt");
foreach ($dir as $filename) {
    if (! preg_match("^_+", $filename, $match) { // doesn't show if 1st char is _
        echo "$filename size " . filesize($filename) . "\n";
    }
}

but instead use glob()'s own regex to avoid loading unnecessary files in the first place, assuming this will be faster.