$re = '/,(-?\d{1,2}\.\d{6,},-?\d{1,2}\.\d{6,}),/';
$str = 'photoname.jpg,99.3333,14.44556,53.345533,28.345533,foo,,
photoname.jpg,53.345533,28.345533,,,,';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php