Fluorescein fundus angiography with scanning laser ophthalmoscope. Visibility of leukocytes and platelets in perifoveal capillaries.

The authors performed fluorescein fundus angiography in 130 eyes using a scanning laser ophthalmoscope (SLO). Capillaries were observed in the perifoveal area in 63 eyes. In these 63 eyes, numerous fluorescent dots were seen flowing through the capillaries. This feature allowed identification of the direction and velocity of blood flow in the retinal capillaries. The distance from 1 dot to the next was widely variable and averaged 100 microM. The velocity of flow was faster in precapillary arterioles, slower in capillaries, and again faster in postcapillary venules. The dots were much more numerous in an eye with leukemia and less numerous in an eye with idiopathic thrombocytopenic purpura. Staining of whole blood from three healthy persons with fluorescein sodium resulted in prompt and intense staining of leukocytes and platelets. These findings indicate that the observed fluorescent dots in perifoveal capillaries correspond to leukocytes and platelets in the circulating blood.