In Setup> Users> Manage Roles and Permissions you can activate the permission View only assigned resources for specific roles (eg. Operator)
View only created patients
These permission restricted to view / book / edit only assigned users and their appointments. If OFF, the user has permissions for all resources.
Once you activate it for the operator, you need to search that user in Manage System User> click on his name> Permissions> select the assigned resources (whose appointments/ patients can be seen)
NB: The operator is just an example, but can be applied for all the users.