Visualisation of retinal blood flow by laser speckle flow-graphy

A new method is demonstrated to visualise the microcirculation map of the human retina using a dynamic laser speckle effect. The retina is illuminated with a diode laser spot through a retinal camera, and its speckle image is detected by an area sensor. The output signal from the sensor is digitised, and the data for more than a hundred scannings of the speckle image are stored in a mass image memory. The difference between a pair of successive image data was calculated and integrated for each pixel. The results were displayed in colour graphics showing the spatial distribution of the blood flow in the retina.