Abstract
Purpose:
To evaluate and compare retinal blood flow measurements in normal eyes and eyes with varying levels of diabetic retinopathy (DR) using Doppler Fourier-domain optical coherence tomography (FD-OCT).
Methods:
Twenty five eyes of 19 subjects with varying levels of DR(10 eyes with severe non proliferative DR and 15 eyes of untreated proliferative DR) were recruited for this IRB-approved prospective study, and compared with twenty five eyes of 25 healthy control subjects. All subjects (cases and controls) underwent Doppler OCT imaging using a standardized, previously-published double circular scan protocol consisting of eight circumpapillary circles which transected all major blood vessels entering/exiting the optic nerve head. Scans were obtained using an Optovue RTvue FD-OCT. Color disk photos and cube/volume scans of the optic nerve head were also obtained to aid in vessel identification and quantification. Doppler OCT scans and accessory imaging data were imported into Doppler OCT of Retinal Circulation (DOCTORC) grading software for refinement of vessel positions and calculation of total retinal blood flow (TRBF) and other vascular parameters (e.g. venous and arterial cross-sectional area). Measurements were compared between the cases and controls.
Results:
The age of the DR group was (Mean ± SD) 51.47 ± 7.37 years, similar (p=0.96) to the normal group (56.08 ± 5.82 years). The mean TRBF was significantly (p=0.05) lower in DR eyes (Mean ± SD; 40.33± 17.07 (range; 16.77 - 80.84) µl/min)compared with normal eyes 46.09 ± 10.19 (range; 32.51 - 64.58) µl/min. There was no significant difference in the total cross-sectional areas of either veins or arteries between the DR and normal groups. TRBF in untreated PDR eyes was 43.34 ± 20.11 (range; 16.77 - 80.84), compared with 35.80 ± 10.48 (range; 20.69 - 49.56) in eyes with severe NPDR. The difference in means was not statistically significant (p=0.14), though the TRBF appears to be more variable in the PDR group.
Conclusions:
Total retinal blood flow was significantly lower in eyes with diabetic retinopathy compared to normal eyes. Retinal blood flow as determined by Doppler OCT may be a potentially useful parameter for evaluating patients with diabetic retinopathy and warrants further investigation.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)