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Delia Cabrera DeBuc, Kyoung-A Cho, Yang Wu, Wen-Hsiang Lee, JoAnne O'day, Elizabeth A. Crocco, Abhishek Rege; Volumetric Blood Flow Changes in the Retina During Mild Cognitive Impairment: Early Results. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1853.
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© ARVO (1962-2015); The Authors (2016-present)
Studies have indicated that subjects with mild cognitive impairment (MCI) may experience changes in retinal function. Using a speckle-based imager, the XyCAM RI, this study examined volumetric blood flow in the retinae of subjects with MCI, healthy subjects (controls), and subjects with possible confounding factors of non-proliferative diabetic retinopathy (NPDR) or Type 2 diabetes (T2D) without retinopathy.
Twenty-eight eyes of 17 subjects (4 controls, 4 T2D, 4 NPDR, 5 MCI) were imaged using the XyCAM RI. The imager acquires laser speckle images of a region of the retina centered on the optic disc over a six-second duration and through speckle contrast computations, produces video data of blood flow velocity (BFV) indices that can be resolved spatially and temporally (Figure 1a). Heart rate information is simultaneously obtained using a pulse oximeter and used to normalize BFV information. BFV values were aggregated in vessel-specific regions overlaying each major arterial and venous branch emerging from the optic disc within each image frame to obtain the temporal trend of Volumetric Blood Flow (VBF). The total blood volume being pumped through each vessel in a cardiac cycle (“volumetric change”) was estimated by integrating the VBF waveform over the cardiac cycle (Figure 1b) and averaging across multiple cardiac cycles in the six-second dataset. The ratio of the VBF change in arteries to veins was compared across each patient group using ANOVA and independent sample t-tests.
The ratio of the VBF change in healthy (44.25±18.28 years), T2D (60.50±5.69 years), NPDR (59.75±7.68 years), and MCI subjects (71±6.54 years) was 0.81 ± 0.08, 0.79 ± 0.19, 0.80 ± 0.19, and 1.00 ± 0.17 (arbitral units), respectively. As shown in Figure 2, there were significant differences in total VBF change in healthy vs. MCI subjects as well as in T2D vs. MCI subjects (both p<0.05), whereas there were no significant differences in healthy vs. T2D subjects nor healthy vs. NPDR individuals.
Our results show preliminary evidence, in a small number of subjects, of altered blood flow dynamics in retinal vessels during mild cognitive impairment that is different than changes that are typical to diabetic eyes. However, because our study sample was small, this is an observation that has no statistical validity because of the small N involved, but clearly deserves further investigation.
This is a 2020 ARVO Annual Meeting abstract.
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