Validating field to contain only numbers separated by commas

I'm making a form validation callback in code igniter. I'm trying to validate an input that needs to be numbers separated by commas, no spaces. For example

1,2,3,4,5 221,78,4,82,991,12 10001,10010,20010 etc

Whats the best way to validate this regex? Some other PHP wizardry?

Why not a regex like this?

/^(\d+,)*\d+$/

Here's an expression that won't require any backtracking.

/^(?:\d+(?:,|$))+$/

The non-capturing groups (?:regex) also make it faster.