Purpose: To evaluate the accuracy of a prototype electronic device for recording eye drop usage.
Participants and methods: Ten volunteers were randomly assigned to one of five usage patterns designed to mimic common patterns of use in glaucoma patients from 100% compliant to 50% compliant. All participants agreed to adhere to a pre-determined "dosing" schedule for 15 days using the monitoring/reminder device to instill artificial tears. Participants also recorded drop usage in a diary. The main outcome measures were device accuracy and reproducibility. Device accuracy was defined as the magnitude of the difference between the diary and device output for three variables: date, number of drops, and instillation time.
Results: Date stamping by the device was 100% accurate. The mean +/- SD time difference between the device and the diary was -2.0 +/- 19.7 minutes when data from all participants was pooled. In seven of the ten participants, the device did not record at least one drop. The mean +/- SD difference in the number of drops recorded by the device minus the diary was 0.16 +/- 0.97 when data from all participants was pooled.
Conclusions: The prototype compliance reminder/monitoring device may underestimate compliance in some patients. The date and time stamping mechanisms were generally accurate and reproducible.