Honestly, I think the best way to find an optometrist to shadow is to ask your very own optometrist! If you don't allready have one-shame on you if you don't-maybe get a routine eye exam, talk to the optometrist, and see what happens. Also, last summer I worked for an OD at his office. I would recommend applying to many local practices, both commercial and private. While many may not get back to you, I'm sure one will respond. Most optometrist's seem more than willing to help others interested in optometry. Just ask around a little more! You'll find someone! Let me know if you have any more questions.
Matt