Purpose: To investigate macular vessel density (MVD) and structural alterations in untreated normal tension glaucoma (NTG) with a hemifield defect (HFD) and to compare these with the findings in healthy eyes.
Study design: Case series with a healthy group for comparison.
Methods: Thirty-four eyes of 34 untreated NTG patients with HFD and 28 eyes of 28 healthy subjects were enrolled. RTVue-XR AvantiTM (Optovue, Inc.), a combined OCT-A and SD-OCT system, was used to determine MVD and inner macular thickness (IMT) measurements. Mean circumpapillary retinal nerve fiber (cpRNFL) and macular ganglion cell complex (mGCC) thicknesses were measured with the RTVue-100TM (Optovue, Inc.). Wilcoxon signed-rank test was used to evaluate differences between defective and normal hemifields in NTG eyes and Mann-Whitney U test to evaluate differences between normal hemifields in NTG eyes and healthy eyes.
Results: In comparison with healthy eyes, the normal hemifields of NTG eyes showed significantly reduced MVD, as well as cpRNFL and mGCC thicknesses, although IMT did not differ between the two groups. The defective hemifield in NTG eyes showed significantly reduced IMT, as well as cpRNFL and mGCC thicknesses, compared with the normal hemifield, although MVD did not differ between the two hemifields.
Conclusion: Hemodynamic deficiencies and structural damage might have already begun in the perimetrically normal hemifields of NTG eyes. Further studies are needed to elucidate whether the reduction in MVD may precede structural changes or the reduction in vasculature and structural loss may vary with disease severity in at least in some cases.
Keywords: Hemifield defect; Macular vessel density; Normal tension glaucoma; Optical coherence tomography angiography.