An ibopamine challenge is a novel technique for assessing glaucoma using ibopamine, a topical drug which temporarily increases aqueous production. We aimed to determine whether change in intraocular pressure (IOP) and/or optic cup volume (OCV) during the test differentiated between glaucoma patients at different stages of disease; namely, glaucoma suspects (GS), glaucoma patients who are stable (SG) and glaucoma patients who have demonstrated rapid progression (PG).Design
Non-randomized clinical trial evaluating a diagnostic test.Participants
Sixty-one patients were recruited through glaucoma clinics at the Flinders Medical Centre (24 GS, 24 SG and 13 PG).Methods
Patients underwent IOP measurement and OCV assessment using optical coherence tomography. Two drops of ibopamine 2% solution were instilled into the study eye of each patient. After 45 min, IOP and OCV were reassessed. Changes from baseline were compared between groups.Main Outcome Measure
Change in IOP and OCV after ibopamine challenge.Results
Following the ibopamine challenge, IOP increased by 1.8 mmHg for GS patients, 4.5 mmHg for SG patients (P = 0.003) and 8.1 mmHg for PG patients (P < 0.0001). OCV increased by 0.2% for GS patients, 0.6% for SG patients and 5.5% for PG patients. This was not significantly different between GS patients and SG patients; however, it was significantly different between GS patients and PG patients (P < 0.0001), and between SG and PG patients (P = 0.001).Conclusion
GS patients may be differentiated from those with SG or PG by their IOP response, and SG may be differentiated from PG patients by their change in OCV following an ibopamine challenge.