[Analysis of choroidal blood flow by laser speckle flowgraphy]

We applied real-time laser speckle flowgraphy (RLSFG) to quantitate the choroidal circulation. RLSFG was developed utilizing the laser speckle phenomenon. A diode laser, 830 nm in wavelength, serves as the light source. The quantitative index of blood flow velocity is represented as normalized blur (NB), or square blur rate (SBR). This method was applied to the posterior fundus of monkey and human eyes. While one measurement covers a fundus area of 1 mm x 1 mm, it is possible to measure a wider fundus area by montage. The wide color maps showed the architecture of choroidal vessels. It was possible to measure the choroidal blood flow in areas free of major retinal vessels. Application of the method to 3 eyes of retinal artery occlusion and 4 eyes of geographic choroiditis showed that the obtained SBR values in normal fundus is derived 25% from the retinal and 75% from the choroidal circulation. The findings show the potential value of RLSFG in quantitating the choroidal blood flow in situ.