NONINVASIVE ASSESSMENT OF CEREBRAL COLLATERAL BLOOD-SUPPLY THROUGH THE OPHTHALMIC ARTERY

We assessed the potential of 2-MHz pulsed-wave transorbital Doppler ultrasonography to delineate the role of the ophthalmic artery as a source of collateral cerebral blood supply by comparing oculopneumoplethysmography, transorbital Doppler ultrasonography, periorbital continuous-wave Doppler ultrasonography, and transcranial Doppler ultrasonography in 25 patients with unilateral internal carotid artery occlusion and five controls with 10 normal internal carotid arteries. Systolic ophthalmic artery blood velocity was reduced ipsilateral to an internal carotid artery occlusion (38.2 +/- 10.2 cm/sec) compared with the contralateral and control velocities (46.0 +/- 10.3 and 47.5 +/- 6.8 cm/sec, respectively; p < 0.05). Ophthalmic systolic pressure measured by oculopneumoplethysmography was 94.7 +/- 13.2 mm Hg ipsilateral to an internal carotid artery occlusion compared with 108.4 +/- 15.3 mm Hg on the contralateral side (p < 0.01). Transorbital and periorbital Doppler ultrasonography detected reversed ophthalmic artery blood flow ipsilateral to an internal carotid artery occlusion in 44.0% and 40.0% of the patients, respectively. Systolic middle cerebral artery blood velocity was 55.2 +/- 22.3 cm/sec ipsilateral to an internal carotid artery occlusion compared with 79.4 +/- 23.5 cm/sec on the contralateral side (p < 0.05) and 101.2 +/- 18.9 cm/sec in the controls (p < 0.05). Reversed ophthalmic artery blood flow was associated with a low middle cerebral artery blood velocity and the lack of major intracerebral collaterals. Transorbital Doppler ultrasonography permits noninvasive evaluation of the ophthalmic artery. Transorbital Doppler measurements correlate with those from oculopneumoplethysmography and transcranial Doppler ultrasonography, reflect the hemodynamic consequences of internal carotid artery occlusion, and demonstrate the importance of the ophthalmic artery as a source of collateral blood supply to the brain.