Often someone will provide a comment that might be a request for clarification or they might be pointing out a simple typo or a problem. When you correct that problem there is no way for the commenter to know things have changed.
How about making it so that you can flag a comment such that the commenter gets notified that the post has changed and that you'd like them to reevaluate their comment.
This shouldn't be an automatic notification (as previously suggested) as you might be correcting or modifying something completely unrelated to the comments. Also the edit may only be related to some of the comments.
To stop possible abuse you'd mark the comment as "flagged" which would remain in place until the commenter dismissed it. With an active flag you can't flag it again.
Additionally you may want to require an edit to flag a comment.
It would also be good to have a tab of such flagged comments available to each user.