The invention provides a supplemental device (2) configured for removable attachment to a medicament injection device (1), the supplemental device comprising a display (21), a processor arrangement(24), at least one memory(241) and an image capturing component(25). The processor arrangement is configured to cause the supplemental device to: use the image capturing component to capture successive images of a medicament dosage indicated by a medicament dispensing device； successively display the captured images on the display； perform optical character recognition on captured images thereby to identify medicament dosage indicated by the medicament dispensing device when the images were captured； and make a non-transient record of delivered dosage information in the at least one memory based at least in part on the identified medicament dosage.
