Color Doppler Imaging Analysis of Retrobulbar Blood Flow Velocities in Primary Open-Angle Glaucomatous Eyes: A Meta-Analysis

BACKGROUND To analyze the diagnostic value of color Doppler imaging (CDI) of blood flow in the retrobulbar vessels of eyes with primary open-angle glaucoma (POAG). METHODS Pertinent publications were retrieved from the Cochrane Central Register of Controlled Trials, PubMed and the ISI Web of Knowledge up to October 2012. Changes in peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) of the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary artery (SPCA) of POAG eyes and normal controls were evaluated by CDI. Subgroup analyses were conducted according to whether patients received IOP-lowering drugs treatment and were defined as treated and untreated. RESULTS PSV and EDV were statistically significantly reduced in the OA of POAG eyes (P = 0.0002; P<0.00001; respectively), with significant heterogeneity (P(heterogeneity)<0.00001, I²  = 94%; P(heterogeneity)<0.00001, I²  = 85%; respectively). Similar results were demonstrated for the CRA (P<0.00001; respectively) and SPCA (P = 0.005; P<0.00001; respectively), with significant heterogeneities for both the CRA (P(heterogeneity)<0.00001, I²  = 81%; P(heterogeneity)<0.00001, I²  = 98%; respectively) and the SPCA (P(heterogeneity)<0.00001, I²  = 96%; P(heterogeneity)<0.00001, I²  = 93%; respectively). Significant increases in RI were found in all retrobulbar vessels (P<0.00001; respectively), with significant heterogeneities (P(heterogeneity)<0.00001, I²  = 95%; P(heterogeneity)<0.00001, I²  = 94%; P(heterogeneity)<0.00001, I²  = 97%; respectively). CONCLUSIONS This meta-analysis suggests that CDI is a potential diagnostic tool for POAG.