Abstract
Age-related macular degeneration is associated with reduced perfusion of the eye; however, the role of altered blood flow in the upstream ophthalmic or internal carotid arteries is unclear. We used ultra-high-field MR imaging to investigate whether the diameter of and blood flow in the ophthalmic artery and/or the ICA are altered in age-related macular degeneration and whether any blood flow changes are associated with disease progression. Twenty-four patients with age-related macular degeneration and 13 similarly-aged healthy controls participated. TOF and high-resolution dynamic 2D phase-contrast MRA (0.26 × 0.26 × 2mm3, 100-ms effective sampling rate) was acquired at 7T. Vessel diameters were calculated from cross-sectional areas in phase-contrast acquisitions. Blood flow time-series were measured across the cardiac cycle. The ophthalmic artery vessel diameter was found to be significantly smaller in patients with age-related macular degeneration than in controls. Volumetric flow through the ophthalmic artery was significantly lower in patients with late age-related macular degeneration, with a significant trend of decreasing volumetric ophthalmic artery flow rates with increasing disease severity. The resistance index was significantly greater in patients with age-related macular degeneration than in controls in the ophthalmic artery. Flow velocity through the ophthalmic artery and ICA was significantly higher in patients with age-related macular degeneration. Ophthalmic artery blood flow as a percentage of ipsilateral ICA blood flow was nearly double in controls than in patients with age-related macular degeneration. These findings support the hypothesis that vascular changes upstream to the eye are associated with the severity of age-related macular degeneration. Additional investigation into the potential causality of this relationship and whether treatments that improve ocular circulation slow disease progression is warranted.
Highlights
MethodsTwenty-four patients with age-related macular degeneration and 13 -aged healthy controls participated
BACKGROUND AND PURPOSEAge-related macular degeneration is associated with reduced perfusion of the eye; the role of altered blood flow in the upstream ophthalmic or internal carotid arteries is unclear
Volumetric flow through the ophthalmic artery was significantly lower in patients with late age-related macular degeneration, with a significant trend of decreasing volumetric ophthalmic artery flow rates with increasing disease severity
Summary
Twenty-four patients with age-related macular degeneration and 13 -aged healthy controls participated. Subjects with different stages of AMD and aged controls participated in this study, approved by the Partners Human Research Committee, after providing written informed consent. Patients were referred from two Boston-area ophthalmologists who provided patients’ diagnostic information, and the stages of AMD were confirmed by two retina specialists (N.K.W. and P.J.R.). Healthy controls were identified using advertisements in the greater Boston area and included spouses of patients enrolled in the study. Exclusion criteria for both patients and controls included contraindications for MR imaging, color vision deficiency/color blindness, and a history of neurologic or psychiatric illnesses.
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