Abstract
Purpose: :
To analyze retinal blood flow characteristics of diabetic eyes using the Retinal Functional Imager (RFI) and standard imaging techniques including fundus photography, fluorescein angiography (FA), and Spectral Domain OCT/SLO (SD-OCT) to evaluate the relationship between occurrence of cilioretinal arteries and macular edema, and to look for evidence cilioretinal-retinal collaterals.
Methods: :
Patients with a diagnosis of diabetic retinopathy were included. All patients underwent fundus photography, FA, SD-OCT and RFI imaging. The presence of cilioretinal artery (CilRA) was established using color/red-free fundus photos, FA and RFI. Two groups of eyes were created according to the presence (CilRA group) or absence (NoCilRA group) of cilioretinal artery or arteries in the studied eye.Cilioretinal arteries were defined as vessels which originate at the optic disc without evidence of communication with the central retinal artery, loop over the margin of the disc and fill with fluorescein dye along with the choroid.
Results: :
Thirty nine eyes with diabetic retinopathy were included. Cilioretinal artery was identified in 15 eyes (38.4%). In the CilRA Group, SD-OCT evidence of macular edema was observed in 86.7% (13 out of 15 eyes), whereas macular edema was observed on SD-OCT in 29.2% (7 out of 24 eyes) in the NoCilRA group. Mean blood flow velocities in retinal arteries and veins were significantly higher in diabetic eyes with cilioretinal artery (p = 0.04 and p = 0.005, respectively). Mean velocity in cilioretinal arteries was significantly higher in comparison to the mean arterial blood velocity (p = 0.03). In CilRA group, cilioretinal-retinal collaterals, assessed by RFI, were detected in 4 (26.7%) out of 15 eyes with cilioretinal arteries. Mean velocity in retinal veins was significantly lower when cilioretinal-retinal collaterals were present (p = 0.008). In NoCilRA group, mean velocity in retinal veins was significantly higher in eyes with macular edema in comparison to the eyes without macular edema (p = 0.03).
Conclusions: :
Using the RFI in conjunction with standard fundus imaging techniques, the presence of cilioretinal artery in diabetic eyes was found to be associated with increased retinal blood flow velocity and increased occurrence of diabetic macular edema. The occurrence of cilioretinal-retinal collaterals was also noted, however, the pathophysiologic significance of this finding requires further investigation.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy • blood supply