Systemic Blood Pressure and Ocular Perfusion Pressure Affects Blood Flow to the Optic Nerve Head in Glaucoma Patients with Diabetes

Abstract

Purpose: To examine the relationship between systemic blood pressure (BP) and ocular perfusion pressures (OPP) with blood flow in the temporal (TPCA) and nasal (NPCA) short posterior ciliary arteries in open-angle glaucoma (OAG) patients with and without diabetes mellitus (DM).

Methods: 75 patients with OAG (17 with DM; 58 without DM) were assessed at baseline and three year follow-up for BP, OPP and blood flow velocities and vascular resistance in the TPCA and NPCA using color Doppler imaging (CDI). Systolic (SBP) and diastolic (DBP) blood pressure (ambulatory) were measured and OPP was calculated as: OPP=2/3[DBP+1/3(SBP-DBP)]-intraocular pressure (IOP). Systolic (SPP), diastolic (DPP) and mean (MPP) perfusion pressures were also calculated as SBP-IOP, DBP-IOP and mean arterial pressure (MAP)-IOP, respectively. Pearson correlations were calculated to evaluate the associations between measurements at baseline and between the changes in measurements between baseline and three years.

Results: In OAG patients with DM, changes in SBP, MAP, SPP, OPP and MPP strongly correlated to changes in TPCA end diastolic velocity (EDV) [r=0.88 to 0.80 (DM); r=0.07 to -0.03 (non-DM)] and resistive index (RI) [r=0.76 to 0.53 (DM); r=-0.14 to -0.19 (non-DM)] compared to non-DM OAG patients with statistically significant differences between groups [p<0.0006; p<0.0148]. In OAG patients with DM, changes in DBP, DPP, OPP and MPP were also strongly correlated to changes in TPCA peak systolic velocity (PSV) [r=0.77 to 0.74 (DM); r=0.13 to 0.02 (non-DM); between groups (p<0.0042)]. In OAG patients with DM, changes in SBP, DBP, MAP, SPP, DPP, OPP and MPP strongly correlated to changes in NPCA EDV [r=0.82 to 0.35 (DM); r=-0.07 to -0.37 (non-DM); between groups (p<0.0351)]. Changes in SBP, MAP, SPP, and MPP were also correlated to changes in NPCA PSV [r=0.70 to 0.48 (DM); r=0.00 to -0.11 (non-DM); between groups (p<0.0445)].

Conclusions: In OAG patients with diabetes, changes in short posterior ciliary artery blood flow were strongly correlated to changes in BP and OPP. These correlations were weak for OAG patients without diabetes and the differences between groups were statistically significant. This data suggests that OAG patients with diabetes may have impaired vascular autoregulation during fluctuations in systemic BP and OPP.

Keywords: 498 diabetes • 436 blood supply