Prospective Retinal Hemodynamic Changes in Diabetic Macular Edema

Abstract

Purpose:: To investigate prospective change in retinal arteriolar hemodynamics in a cohort of patients with varying levels of risk for the development of clinically significant diabetic macular edema (CSDME) and to correlate these parameters to systemic measures of diabetes control and complications.

Methods:: The sample comprised 4 groups. G1: 37 non-diabetic controls (mean age 53.8yrs, SD 8.4); G2: 42 patients (54.4yrs, 8.4) with diabetes but no clinically visible retinopathy; G3: 38 patients (57.6yrs, 7.3) with hard exudates and/or microaneurysms within the macular but no clinically visible DME; G4: 27 patients (58.0yrs, 6.1) with pre-treatable. Volunteers completed 1 year follow-up or progressed to the point of requiring laser treatment for CSDME. Retinal arteriolar diameter, blood velocity and flow were assessed using the Canon Laser Blood Flowmeter (CLBF). Multiple CLBF measurements were acquired from a superior temporal arteriole. ANOVA was used to analyse differences both within and between groups at baseline and 1 year follow-up. Pearson correlation coefficients were used to compare retinal hemodynamics with systemic measures.

Results:: Max:min velocity ratio was elevated with increasing risk for the development of CSDME at baseline (trend, p=0.060) and follow-up (p=0.025). Arteriolar diameter tended to reduce in all groups over the period of follow-up (p<0.056), except for G4 which showed a significant increase in diameter compared to G1 (p=0.025). Retinal blood flow increased in G4 compared to controls (p=0.039), while all other groups showed a reduction in flow. Changes in velocity, flow and max:min velocity ratio were correlated to changes in blood pressure; these correlations were particularly significant for G3 and G4 (r=-0.629, p<0.001 highest correlation).

Conclusions:: Patients with DME showed distinctly different arteriolar hemodynamic progression characteristics than the other 3 groups. G4 exhibited a higher max:min velocity ratio and a progressive increase in diameter and flow over the follow-up and these changes were correlated with changes in blood pressure.

Keywords: diabetic retinopathy • edema • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)