The inter-visit variability of retinal blood flow velocity measurements using retinal function imager (RFI).

Background: To determine the inter-visit variability of retinal blood flow velocities (BFVs) using a retinal function imager (RFI) in healthy young subjects.

Methods: Twenty eyes of 20 healthy young subjects were enrolled. RFI imaging was performed to obtain the BFVs in retinal arterioles and venules in a field measuring 7.3 × 7.3 mm2 (setting: 35 degrees) centered on the fovea, and repeated measurements were obtained on two separate days. The inter-visit variability of BFVs was assessed by the concordance correlation coefficient (CCC) and coefficient of variance (CV).

Results: At the first visit, the mean BFV was 3.6 ± 0.8 mm/s and 3.0 ± 0.7 mm/s in arterioles and venules, respectively, which were not significantly different from those at the second visit (the BFV of arterioles was 3.5 ± 0.8 mm/s, and the BFV of venules was 3.0 ± 0.7 mm/s, P  > 0.05, respectively). The CCC was 0.72 in the BFVs of arterioles and 0.67 in venules, and the CV was 10.8% in the BFVs of arterioles and 11.0% in venules.

Conclusion: The inter-visit variability using the retinal function imager (RFI) with a large field of view appeared to be good and comparable to previously reported intra-visit and inter-eye variability.