Abstract
Purpose: :
To study changes of retinal blood flow velocity in patients with early diabetes mellitus (DM) without morphological changes in the retina. We used the Retinal Function Imager (RFI, Optical Imaging Ltd., Rehovot, Israel) implementing a new, non-invasive diagnostic approach to measure blood flow velocity.
Methods: :
Twenty three eyes of 14 patients with early DM and 51 eyes of 31 healthy subjects were enrolled. All subjects had a detail ophthalmic evaluation revealing a healthy retina. Blood flow velocity of secondary and tertiary branches of arteries and veins of all patients were acquired using the RFI. Differences among groups were assessed by mixed linear models.
Results: :
There was no statistically significant difference between the average age, sex, heart rate and systolic blood pressure in the diabetes and the healthy group. The diastolic blood pressure in the diabetic patients was lower than in the healthy group (74±11 vs 82±9mmHg respectively, p=0.03). Arterial average velocity of diabetic patients was significantly higher than in the healthy subjects (4.7±1.7 vs 4.1±0.9 mm/sec respectively, p=0.03). Venous velocity was also significantly increased in the DM group (3.8±1.2 vs 2.9±0.5 mm/sec, respectively, p<0.0001). The increase in arterial and venous velocity was noted in all vessels larger than 10 microns but not in smaller caliber vessels. Venous mean width was significantly narrower in the DM group compared with the healthy subjects, while no significant difference was noted in arterial width between the groups.
Conclusions: :
The RFI detected increased blood flow velocity in retinal arteries and veins of patients with early DM with no diabetic retinopathy. The velocity increase was accompanied by decrease in vein caliber in this group, suggesting activation of compensation mechanisms. These findings support the notion that abnormalities in vessel function exist in diabetic eyes prior to the development of clinical apparent retinopathy. The RFI provides a non-invasive technique to assess early haemodynamic abnormalities in the diabetic eye and may assist in screening and monitoring.
Keywords: diabetes • blood supply