Author profile image URL also in comment?

How i can add author profile image also for comments?
i’ve already fixed in page:

/* Show the post author's gravatar if enabled */
								if (get_option('graphene_show_post_avatar') && !is_page()) {
									if (get_the_author_meta('graphene_author_imgurl')) {
									echo '<img class="avatar" src="'.get_the_author_meta('graphene_author_imgurl').'" alt="" style="height: 38px" />';
									} else {
									echo get_avatar(get_the_author_meta('user_email'), 38);
									}
								}

and bottom of article:

/**
			 * Display the post author's bio in single-post page if enabled
			*/
			if (is_single() && get_option('graphene_show_post_author')) :
			?>
            <h4 class="author_h4"><?php _e('About the author', 'graphene'); ?></h4>
            <div class="author clearfix">
            	<?php
				if (get_the_author_meta('graphene_author_imgurl')) {
				echo '<img class="avatar" src="'.get_the_author_meta('graphene_author_imgurl').'" alt="" style="width: 100px" />';
				} else {
				echo get_avatar(get_the_author_meta('user_email'), 100);
				}
				?>

But for comments is really different and i don’t have found a valid way to fix it: function.php

<?php echo get_avatar($comment, apply_filters('graphene_gravatar_size', 40)); ?>
                <?php do_action('graphene_comment_gravatar'); ?>

Any help is more appreciated 🙂