Cavor on "[Plugin: WordPress SEO by Yoast] Image caption in meta description"

WordPress version: WordPress 3.5.1.
WordPress SEO version: 1.4.4
http://www.ligneclaire.info/

Hi,
How Can I remove caption text (<p class="wp-caption-text">) wich appears in meta description if I put a picture before text ?

http://wordpress.org/extend/plugins/wordpress-seo/