Contributors only see comments on their posts


I have implemented the following as a custom function so users (excluding admins) can only see their posts.

add_action('pre_get_posts', 'filter_posts_list');
function filter_posts_list($query)
    //$pagenow holds the name of the current page being viewed
     global $pagenow;

    //$current_user uses the get_currentuserinfo() method to get the currently logged in user's data
     global $current_user;

        //Shouldn't happen for the admin, but for any role with the edit_posts capability and only on the posts list page, that is edit.php
        if(!current_user_can('administrator') && current_user_can('edit_posts') && ('edit.php' == $pagenow))
        //global $query's set() method for setting the author as the current user's id
        $query->set('author', $current_user->ID);

What can I implement similarly so users (again, excluding admins) can only see and respond to comments on their posts?

Any help would be much appreciated! Many thanks!