If combine wouldn't work for you you could just explicitly declare the array k/v.
$lines = file('responders.txt', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$nameArray = array();
$i = 0;
foreach ($lines as $line)
{
echo $i . " > " . $line . "\n";
$nameArray[i] = $line;
$i++;
}