Correlation between capillary blood flow of retina estimated by SLDF and circulatory parameters of retrobulbar blood vessels estimated by CDI in diabetic patients.

BACKGROUND: The aim of this study was to investigate the correlation between the recordings of scanning laser Doppler flowmetry (SLDF) of the retina and the recordings of color Doppler imaging (CDI) of the retrobulbar circulatory parameters in diabetic patients without diabetic retinopathy.
METHODS: Twenty-three diabetic patients without diabetic retinopathy were evaluated using SLDF for the apparent retinal circulation and using CDI for the apparent retrobulbar circulation in the central retinal artery, the central retinal vein and the short posterior ciliary artery. The circulatory parameters estimated in the retinal tissue using SLDF were velocity, volume and flow. The Circulatory parameters that were recorded using the CDI method were peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV), pulsatility (PI) and resistivity index (RI). We obtained the correlation coefficients between parameters of SLDF and CDI. Multiple regression analysis was performed with "flow" parameter of SLDF recordings as a dependent variable and all estimated CDI parameters as independent variables. Multiple linear regression was also performed, including the "flow" parameter of SLDF recordings as a dependent variable and PI of the CDI parameters of all the measured blood vessels as independent variables.
RESULTS: The "velocity" parameter of SLDF was significantly correlated with the PI in the central retinal artery (P=0.02), PI and RI in the central retinal vein (P=0.01; P=0.01) and the PSV, MV, PI and RI in the short posterior ciliary artery, as recorded by CDI (P=0.003; P=0.02; P=0.002; P=0.01). The "volume" parameter of SLDF was significantly correlated with the PI and RI in the central retinal vein (P=0.03; P=0.03) and the PSV in the short posterior ciliary artery (P=0.03), as recorded by CDI. The "flow" parameter of SLDF was significantly correlated with the PI and RI in the central retinal vein (P=0.01; P=0.01) and the PSV, MV, PI and RI in the short posterior ciliary artery (P=0.003; P=0.03; P=0.002; P=0.01) as measured by CDI. The multiple regression analysis was statistically non-significant (P=0.86). The multiple linear regression analysis indicated that from among the PI of the evaluated blood vessels, the PI of the short posterior ciliary artery was the most significant predictor of the "flow" parameter of SLDF (P=0.01).
CONCLUSION: This study suggests a positive correlation between the recordings of SLDF of the retinal tissue and the retrobulbar circulatory parameters of the CDI in diabetic patients without diabetic retinopathy.