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Thalmon R. Campagnoli, Gabor Mark Somfai, Jing Tian, william smiddy, Delia DeBuc; Evaluation of macular microvasculature and blood flow velocities by non-invasive, high-resolution functional imaging in proliferative diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1465.
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We aimed to assess the retinal capillary network and blood flow velocitity (BFV) measurements in proliferative diabetic retinopathy (PDR) using a high resolution, non-invasive functional imaging device.
We enrolled five eyes of four diabetic subjects with PDR and seven eyes of seven healthy control subjects. All study participants underwent routine ophthalmic examination followed by scanning with the Retinal Function Imager (RFI, Optical Imaging Inc., Rehovot, Israel). The built-in software of the RFI device was used to generate nCPMs and to segment the retinal vasculature for BFV measurements. Vessel segments with a velocity coefficient of variation of >45% were rejected and only analyses with <15% of rejected segments per eye were accepted. The number of accepted vessel segments was recorded and their velocity values were exported. Comparisons were made by Mann-Whitney U test, the level of significance was set at 5%.
The nCPMs gave high resolution images of the retinal microvasculature and showed extensive ischemia in all five eyes with PDR. In one eye with PDR BFV was not obtained due to the high number of rejected segments. The retinal arterioles were narrower and significantly less in number in the PDR group, while a comparable number of venules were available for analyses in both groups (arterioles: 11.16±4.16 vs 6.25±2.63 and venules: 12.33±3.07 vs 14.25±5.85 segments/eye, p=0.03 and p=0.25, Healthy vs PDR, respectively). The mean BFV measurements in the arterioles of the PDR group were significantly reduced, while the decrease observed in the venules was not significant (arterioles: 4.74±0.49 vs 3.50±0.68 and venules: 3.39±0.81 vs 2.92±0.44 mm/s, p=0.02 and p=0.41, Healthy vs PDR, respectively).
The RFI is a non-invasive tool for the high resolution functional imaging of retinal microvasculature also enabling the quantitative measurement of retinal blood flow velocities. Our pilot study demonstrated a significant decrease in arteriolar blood flow velocities in the macula and a reduced number of perfused arterioles. Taking also into account the observed narrowing of the arteriolar segments, our results support the highly reduced retinal blood supply in PDR.
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