Abstract
Purpose:
To assess differences in neuroretinal rim area (NRA) and ocular hemodynamic parameters in normal-tension glaucoma (NTG) patients with different intracranial pressure (ICP) values.
Methods:
40 patients (27.5% men, 72.5% women) with NTG (age 61.1(11.5) years) were included in the prospective study. During the study intraocular pressure (IOP), non-invasive ICP, retrobulbar blood flow (RBF) and confocal laser scaning tomography for optic nerve disc (OND) structural changes were assessed. Non-invasive ICP was measured using novel two-depth Transcranial Doppler device (Vittamed UAB, Kaunas, Lithuania), technology based on simultaneous blood flow signals in intracranial and extracranial segments of the ophthalmic artery (OA). RBF was measured using Color Doppler imaging (CDI, Accuvix, Seoul, Korea) in the OA and central retinal (CRA) arteries, assessing peak-systolic (PSV) and end-diastolic (EDV) velocities, and calculated resistance index (RI). Based on statistical mediana patients were divided into 2 groups for comparison: patients with ICP ≥ and < than 8.3 mmHg. The level of significance p<0.05 was considered significant.
Results:
NTG patients had mean ICP 8.8(2.5) mmHg, IOP 13.6(2.1) mmHg, OND size 2.25(0.6) mm2, NRA 1.17(0.35) mm2. Lower ICP was correlated with decreased NRA (r=0.51, p=0.001).<br /> NTG patients with lower ICP (N=20) had significantly lower NRA 1.02(0.3) mm2, than NTG patients with higher ICP (N=20) 1.31(0.3) mm2 (p=0.002), though there were no significant difference in OND size (accordingly, 2.22(0.5) and 2.30(0.6) mm2, p=0.57) and IOP (accordingly, 13.5(2.4) and 13.7(1.8) mmHg, p=0.58). NTG patients with lower ICP had statistically significantly lower OA blood flow velocities (PSV 28.7(8.0), EDV 6.9(3.0) cm/s), compared to NTG patients with higher ICP (accordingly, 35.5(10.2) and 9.4(4.1) cm/s), p<0.04.<br /> <br />
Conclusions:
Normal-tension glaucoma patients with lower ICP had decreased neuroretinal rim area and ocular hemodynamic parameters, compared to patients with higher ICP. Further studies are needed to analyze the involvement of ICP in normal-tension glaucoma management.