Background: Color Doppler imaging has become a useful adjunctive tool in diagnosing ophthalmic vascular disease. However, a paucity of information exists regarding normal values. This investigation was conducted to generate a database of normal retrobulbar circulatory parameters. Methods: The authors prospectively studied the retrobulbar hemodynamic parameters of 53 normal eyes from 32 healthy individuals of various ages, all without risk factors for the development of systemic vascular disease. Preliminary Doppler spectral analysis was used to demonstrate normal carotid arterial, carotid siphon, and ophthalmic vascular anatomy. Results: Mean hemodynamic values were recorded for each retrobulbar vessel. Diastolic blood pressure significantly correlated with ophthalmic arterial end-diastolic velocity (P < 0.05) and pulsatility index (P < 0.05). Although end-diastolic velocity significantly decreased (P < 0.05) and vascular resistance significantly increased (P < 0.05) as a function of age in the posterior ciliary and central retinal arterial circulation, no such correlation was identified in the ophthalmic artery which demonstrated significantly more hemodynamic variability among individuals (P < 0.00001). No significant differences in blood flow or vascular resistance were noted between sexes, fellow orbits, or the nasal and temporal branches of the posterior ciliary artery within individual orbits. Conclusion: Orbital hemodynamic parameters do not appear to be sex dependent or variable between fellow orbits. These data suggest that age and diastolic blood pressure may affect normal orbital blood flow and vascular resistance patterns. Significant interindividual variability is limited only to ophthalmic arterial blood flow.
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