public function getOptionalElementTypes()
{
$optional_element_types = \ElementType::model()->findAll(array('condition' => "event_type.class_name = 'OphCiExamination' AND\n\t\t\t\t\tophciexamination_element_set_item.id IS NULL\n\t\t\t\t\tOR ophciexamination_element_set_item.is_hidden = 0", 'join' => 'JOIN event_type ON event_type.id = t.event_type_id
LEFT JOIN ophciexamination_element_set_item ON (ophciexamination_element_set_item.element_type_id = t.id
AND ophciexamination_element_set_item.set_id = :set_id)', 'order' => 'display_order', 'params' => array(':set_id' => $this->id)));
return $optional_element_types;
}