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Akihito Uji, Masanori Hangai, Sotaro Ooto, Shigeta Arichika, Tomoaki Murakami, Nagahisa Yoshimura; Detection of flow velocity fluctuations associated with erythrocyte aggregation in diabetic retinopathy by using adaptive optics scanning laser ophthalmoscopy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6055.
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© ARVO (1962-2015); The Authors (2016-present)
Adaptive Optics Scanning Laser Ophthalmoscopy (AO-SLO) has enabled noninvasive and direct monitoring of erythrocyte aggregates in the retinal capillaries. In this study, we quantified the blood flow velocity in the parafoveal capillaries of patients with diabetic retinopathy (DR) by using the AO-SLO system prototype developed by Canon Inc.
Ten patients (mean age ± standard deviation [SD], 45.8 ± 16.7 years) diagnosed with DR at Kyoto University Hospital (8 patients with mild nonproliferative DR [NPDR], 2 patients with moderate NPDR) and 8 control subjects without any history of ocular or systemic diseases (mean age, 34.6 ± 8.6 years) were recruited for this study. AO-SLO videos were acquired from the temporal and nasal areas located 0.5° from the foveal center. The scan area of the retina was 1.4 × 2.8°, and scans were recorded for 4 seconds per area at a frame rate of 64 Hz. Erythrocyte aggregates were detected as “dark tails” that were darker than the vessel shadows, and the velocities of all the dark tails observed in both temporal and nasal areas were measured. In subjects whose pulse was measured simultaneously during the AO-SLO video recording, a relative cardiac cycle was assigned to each dark tail velocity in order to investigate the effect of cardiac pulsation on the velocities.
Vessels showing rapid changes in dark tail flow velocity were noted in 6 DR patients, but these vessels were not detected in normal subjects. In these vessels, dark tail flow velocity was extremely low and deformation of the trajectory of the dark tail flow was depicted in the spatiotemporal image. Two such vessels were found in 3 patients and 1 vessel was found in each of the remaining 3 patients. The average velocity change in these vessels was 0.95 ± 0.53 mm/s. Pulse was measured in 6 DR patients and 8 normal subjects, and 220 dark tails were analyzed in total. The velocity of the dark tail in DR patients (1.45 ± 0.52 mm/s) was significantly higher than that in normal subjects (1.33 ± 0.40 mm/s) (P < 0.05).
The velocity of the dark tail in NPDR patients was higher than that in normal subjects. However, at the same time, there were some vessels with extremely slow dark tail flow. Spatiotemporal images were useful in detecting rapid changes in dark tail flow.
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