At baseline, patients will be trained to use the iCare Home tonometer, a handheld device based on rebound tonometry and designed for patients to use at home. After the training session and when patients feel confident, a measurement will be recorded. Thereafter, a new measurement will be obtained by the study staff (an optometrist or a nurse) using the same device. No IOP values will be visible for the examiner at that point. Thereafter, a single IOP measurement will be obtained by the same study staff using Goldmann applanation tonometry (GAT). Patients will then borrow the iCare Home tonometer to meaure their IOP at 06 and 10 am, and at 2, 6 and 10 pm during three consecutive days to obtain an IOP curve. Patients will come for a second visit where new measurements will be made in the same way as at baseline.