add_action( 'admin_head', 'my_icons' );
function my_icons() {?>
<style type="text/css" media="screen">
 #menu-posts-product .wp-menu-image {
 background: url(<?php bloginfo('url') ?>/wp-content/themes/BootWp/img/contactLensemenu.png) no-repeat 6px !important;}
 .icon32-posts-product {
 background: url(<?php bloginfo('url') ?>/wp-content/themes/BootWp/img/contactLensepage.png) no-repeat !important;
    }
</style>
<?php }

add_action( 'admin_head', 'my_icons' );

function my_icons() { ?>
 <style type="text/css" media="screen">
 #menu-posts-product .wp-menu-image, .icon32-posts-product {
     background: url(<?php echo get_template_directory_uri();  ?>/img/contactLensemenu.png) no-repeat center center!important;
 }
 #menu-posts-product .wp-menu-image { background-size:16px 16px!important; }
 .icon32-posts-product { background-size:32px 32px!important; }
 </style>
<?php } ?>