An ICG angiogram-based clinical method for characterizing the choroidal circulation used to assess the hemorrheologic effects of pentoxifylline

Purpose: To demonstrate an indocyanine green (ICG) angiography-based clinic al method for characterizing choroidal blood flow and for detecting changes in choroidal circulation patterns, and by use of that method, to demonstra te that pentoxifylline affects choroidal blood flow. Methods: High-speed ICG angiography was performed in rhesus monkeys before and after intravenous administration of pentoxifylline or saline (which ser ved as a control) while monitoring blood pressure and heart rate. From thes e data, three-dimensional surface maps indicating the instantaneous relativ e distribution of choroidal blood flow during the peak of intra-ocular pres sure pulse systole in a 30 degrees field, centered on the macula, were gene rated to characterize the state of the choroidal circulation at various tim es during the experiments. Results: Comparisons of the 3-dimentional surface maps consistently indicat ed an increase in sub-macular choroidal blood flow occurring within 5 to 10 minutes post-pentoxifylline injection, with a gradual return to baseline l evel 20-40 minutes later. Injection of equal volumes of saline produced no changes in choroidal blood flow. Conclusions: Posterior-pole choroidal blood flow can be characterized as by a three-dimensional surface representing the instantaneous relative distri bution of choroidal blood flow during the peak of intra-ocular pressure pul se systole. Pentoxifylline does, at least transiently, increase submacular choroidal blood flow.