In vivo Doppler holography of the optic nerve head in glaucoma: Response to acute IOP decrease

Doppler holography is a new technique of non-invasive imaging that allows observation of blood flow in retinal vessels. The goal of the present study was to determine if intraocular pressure (IOP) has an effect on the calculation of optic nerve head blood flow using Doppler holography in patients with primary open-angle glaucoma (POAG).

Four patients with POAG or ocular hypertension greater than or equal to 30mmHg were enrolled. The velocity of blood flow in the first branch of the central retinal artery (CRA) was measured before and after surgical lowering of the IOP. The measurements were performed by Doppler holography. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistivity index (RI), and area under the velocity curve (AUC) were calculated for each patient and compared.

Four patients were included in the analysis. The median age was 75.5 years (67-84). The glaucoma was staged as severe in half of the patients. Acquisitions were performed between 1 and 14 days after surgery. A median postoperative decrease in IOP of 23mmHg (20-25.5) was associated with an improvement in diastolic CRA flow [EDV significatively increased (P=0.029)], and RI significatively decreased (P=0.029). Conversely, AUC and PSV did not change significantly.

Reducing IOP in patients with POAG significantly improved diastolic CRA flow, while systolic flow did not appear to change. This pilot study confirms that Doppler holography can precisely measure CRA blood flow.