Retrobulbar haemodynamic changes studied by colour Doppler imaging in glaucoma

To determine the effect of spontaneously elevated intraocular pressure (IOP) on the ocular circulation, and evaluate the result of IOP-lowering procedures in terms of haemodynamics.

Colour Doppler imaging (CDI) was employed to determine the peak systolic velocity (PSV), end-diastolic velocity (EDV) and time average maximal velocity (TAMV), as well as the Pourcelot ratio (PR) and pulsatility index (PI), of the central retinal artery (CRA), posterior ciliary arteries (PCA) and ophthalmic artery. Various CDI parameters of the eyes with elevated IOP were compared with those of the clinically healthy fellow eyes and the control eyes, separately. Also, data from CDI of glaucoma eyes obtained during the period of elevated IOP and then following IOP-lowering procedures were compared, deliberately avoiding the influence of glaucoma medications.

Eyes (n = 12) with elevated IOP showed significantly decreased flow velocities of the CRA and significantly increased PR and PI of the nasal and temporal PCA, compared with the fellow and control eyes, respectively. Following IOP-lowering procedures, the PR and PI of the nasal PCA decreased significantly.

Spontaneously elevated IOP may induce haemodynamic changes in the CRA and PCA, but no significant change is identified in the ophthalmic artery. Flow velocities tend to decrease while the resistance indices tend to increase with elevated IOP. Such haemodynamic changes may reverse following normalisation of IOP.