In one aspect of the present disclosure, a method is disclosed. The method involves: a reader detecting an eye-mountable device within a wireless communication range of the reader, wherein the eye-mountable device includes a transparent material having a concave mounting surface configured to be removably mounted on a corneal surface; wirelessly retrieving from the detected eye-mountable device a first set of data; using the retrieved first set of data to determine that a condition has been satisfied; and responsive to using the retrieved first set of data to determine that the condition has been satisfied, retrieving from the detected eye-mountable device a second set of data.