Blue field entoptic phenomenon and blood velocity in the retinal capillaries.

The blue field entoptic phenomenon consists of the perception of one’s own leukocytes (white blood cells) flowing in the macular capillaries of the retina. A method has been developed for determining the speed of the leukocytes. In this method, the motion of the leukocytes is simulated on a screen by means of a minicomputer system. The subject is instructed to match the motion of the simulated white blood cells with that of his own leukocytes. For this, he can adjust the number and the maximum and minimum speeds of the simulated particles. Measurements in five young subjects with normal fundi indicate that the speed of the leukocytes in the macular capillaries of the retina is pulsatile. Minimum and maximum speeds are approximately 0.5 and 1 mm/s.