Abstract
Purpose: :
Previous studies revealed significantly decreased retrobulbar hemodynamics in normal tension glaucoma (NTG) compared to controls. To evaluate sensitivity and specificity of color Doppler imaging parameters of retrobulbar vessels in NTG using Receiver Operating Curve analysis.
Methods: :
Seventy–eight patients with NTG (mean age 60 ± 12 years) and thirty–five age–matched controls (mean age 59 ± 9 years) were included in a retrospective analysis. Flow velocities (peak systolic velocity PSV and end–diastolic velocity EDV) of the ophthalmic artery (OA), central retinal artery (CRA) and nasal and temporal short posterior ciliary arteries (PCA) were measured by means of color Doppler imaging. Resistive indices (RI= (PSV–EDV)/PSV) were calculated from this data. Using Receiver Operating Characteristic (ROC) curves sensitivity was determined at 90% specificity.
Results: :
Intraocular pressure and blood pressure values were not different between patients and controls. Patients with NTG showed significantly decreased PSV (p=0.001) and EDV (p=0.009) of the CRA and significantly increased RI of the OA (p=0.047) compared to controls. The following sensitivity values at 90% specificity were calculated: PSV of the CRA: 24.4%, EDV of the CRA: 32.1%, RI of the CRA:25.6%, EDV of the nasal PCA: 26.8%, RI of the nasal PCA: 31.0%, EDV of the temporal PCA: 30.7%, RI of the temporal PCA: 29.3%. The PSV and EDV of the OA, the RI of the OA, and the PSV of the nasal and temporal PCA showed sensitivity levels below 15% at 90% specificity.
Conclusions: :
Sensitivity to detect NTG patients with color Doppler imaging was low for all parameters. The EDV of the CRA was the best parameter with 32.1% sensitivity at 90% specificity. Assessing retrobulbar hemodynamics is of minor value to discriminate patients with NTG from controls. The diagnostic power of color Doppler measurements for progression needs to be determined in prospective longitudinal studies.
Keywords: blood supply • imaging/image analysis: clinical