Assessment of human ocular hemodynamics

Vascular abnormality and altered hemodynamics play important roles in many ophthalmic pathologies. Much of our knowledge of ocular hemodynamics was gained from invasive animal research, although a number of noninvasive methods suitable for in vivo use in humans have been developed. Data from these methods now produce a significant literature of their own. Understanding the origins of the data and appreciating their limitations can be difficult. Modern hemodynamic assessment techniques each examine a unique facet of the ocular circulation. No single facet provides a complete description of the hemodynamic state of the eye. These methods have contributed a great deal to our understanding of normal hemodynamics. More importantly, they continue to add to our understanding of altered hemodynamics found in disease. Some have found their way into limited clinical practice. The predominant ocular hemodynamic assessment techniques are reviewed with the aims of introducing the fundamental principles behind each, highlighting their inherent advantages and limitations, highlighting their contributions to understanding ocular physiology, and considering their potential to provide signs for diagnosis.