Abstract
Purpose:
Adaptive Optics Scanning Laser Ophthalmoscopy (AO-SLO) is a noninvasive technique that has enabled direct monitoring of erythrocyte aggregates in retinal capillaries. We analyzed the hemorheological characteristics of diabetic retinopathy (DR) in normal subjects, patients with no-DR (NDR) and patients with nonproliferative DR (NPDR), using spatiotemporal (ST) blood flow images to visualize the blood corpuscles trajectory.
Methods:
AO-SLO images were acquired for 3 groups: 20 healthy Japanese volunteers (mean age, 36.7 ± 11.5 years), 17 diabetic patients with NDR (8 type 1 and 9 type 2 patients; mean age, 39.9 ± 11.7 years), and 8 diabetic patients with NPDR (3 type 1 and 5 type 2; mean age, 38.9 ± 14.6 years). AO-SLO images of the temporal and nasal areas located 0.25-0.5 mm from the foveal center were obtained. The retinal area scanned was 1.4 × 2.8°, and the scans were recorded for 2-4 s per area at a frame rate of 64 Hz. The erythrocyte aggregate velocities corresponding to a relative cardiac cycle were calculated using the ST images of the target vessels. To evaluate the erythrocyte aggregate properties, the elongation rate was calculated using the ST images of the 3 groups.
Results:
The total average velocities were 1.26 ± 0.22 mm/s in the normal group, 1.31 ± 0.21 mm/s in the NDR group, and 1.62 ± 0.37 mm/s in the NPDR group. No significant difference was observed between the average velocities of the normal and NDR groups (p = 0.789). On the other hand, the average velocities of the NPDR group were higher than those in the normal (p = 0.005) and NDR (p = 0.028) groups. The average elongation rates of the 3 groups were 0.67 ± 0.20, 0.39 ± 0.19, and 0.35 ± 0.12, respectively. Statistically significant differences were observed between the elongation rates of the normal and NDR (p = 0.005) groups as well as between those of the normal and NPDR (p = 0.012) groups; however, no difference was observed in the elongation rates of the NDR and NPDR (p = 0.996) groups.
Conclusions:
AO-SLO is a noninvasive technique, which provided hemorheological information on erythrocyte aggregates and enabled evaluation of the elongation rate of erythrocyte aggregates in diabetic patients in early stages of DR. Erythrocyte aggregates can serve as a surrogate marker for the detection of diabetic retinopathy before clinical appearance.
Keywords: 550 imaging/image analysis: clinical •
499 diabetic retinopathy