The eye provides a window through which a complete vascular system of arteries, capillaries, and veins can be directly observed. An adaptive optics scanning laser ophthalmoscope (AOSLO), a custom-built optical microscope for the living human eye, can be used to directly acquire videos of blood flow through the smallest capillaries in the eye. However, in the absence of invasive contrast agents, the contrast of blood cells and capillaries is very low. Moreover, it is difficult to determine the locations of all capillaries, and therefore tracking and speed quantification of blood cells is hindered. In human eyes, contrast agents such as fluorescein are typically used only in the later stages of certain diseases, due to the possibility of adverse side effects. Instead, we used intrinsic signals from moving blood cells to create contrast. By applying custom motion contrast enhancement methods to AOSLO videos, we were able to noninvasively visualize complete capillary networks as well as characterize hemodynamics through the capillaries in the eye. We investigated capillaries in healthy and diseased eyes; in diabetes, we found evidence of capillary remodeling even before conventional clinical methods detected any changes. In summary, motion signals can be used to generate intrinsic contrast for visualization and analysis of capillaries and blood cells. These methods are important for evaluating diseases that affect the microcirculation, such as diabetes.


Seminar, June 21, 2011, 12:00. Seminar Room

Hosted by Prof. Melike Lakadamyali