Update line 25 of the pp_confirm.php page to:
$PPVals = $_SESSION["WASF_CheckoutWizard_NewFromBlank_Default"];
that way the new form elements will be carried over and can be referenced from the persistent form just like the current ones.
I'd probably add a column to the cart named "IsContact" and set it to that value from the database. That way you can just check the total of that column to determine if you make those fields required... if the total is greater than zero there is at least one contact lens.