Abstract
Purpose: :
To characterize the Doppler Waveform of the Ophthalmic Artery (OA) by color Doppler imaging (CDI). To investigate whether the Doppler variables early systolic acceleration (ESA) and systolic/diastolic mean velocity ratio (Sm/Dm) can provide useful diagnostic information in patients with glaucoma.
Methods: :
Analysis of CDI examinations of the retrobulbar circulation of patients with primary open-angle glaucoma (POAG, n=102), normal tension glaucoma (NTG, n=89) and healthy controls (n=59). The Doppler waveform of the OA of one eye per patient was calculated by a condition-masked investigator. One-way Anova, Chi-Square and Spearman correlation tests were used to determine differences, establish comparisons and to explore associations between variables, respectively.
Results: :
The overall Doppler waveform presented a shift to the right in the glaucoma groups, with a significantly lower Sm/Dm ratio when compared to the control group (Healthy: 2.94±0.86, POAG: 2.60±0.67, NTG: 2.63±0.84; p=0.01), despite no statistical difference in the OA velocities or resistance index (p ranged between 0.08 and 0.96) and similar mean ocular perfusion pressures (MOPP, p=0.88). ESA was significantly lower in the glaucoma groups (Healthy: 688.8±484cm.s-2, POAG: 548.1±419cm.s-2, NTG: 548.5±337cm.s-2; p=0.03). MOPP only correlated with waveform variables in the NTG group (ESA, p=0.03, r=0.24; AT, p=<0.01, r=-0.37), but not in the POAG or healthy groups (p>0.15). In the glaucoma groups, a negative correlation was detected between Sm/Dm ratios and retinal nerve fiber layer thickness in the NTG group (p=0.02; r=-0.25) and visual field defects in the POAG group (p=0.01; r=-0.25).
Conclusions: :
The ESA and Sm/Dm variables maybe useful in differentiating between Doppler waveforms in glaucoma patients that might otherwise go unnoticed. This shift of blood flow towards the diastolic component could be associated with decreases in perfusion pressures. These changes maybe particular significant in glaucoma patients, where they may correlate with increased glaucoma damage.
Keywords: blood supply • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)