Relationship between Macular Vessel Density and Focal Electroretinograms in Early Normal Tension Glaucoma

Purpose: To evaluate the relationship between the macular vessel density and photopic negative response (PhNR) amplitude of focal electroretinograms (ERGs) in patients with early-stage normal tension glaucoma (NTG). Materials and Methods: This prospective cross-sectional study included a total of 42 subjects with early-stage NTG. Optical coherence tomography angiography was used to measure macular vessel density, and focal ERGs were elicited by a white light stimulus (30 cd/m²) with background light (1.5 cd/m²). The amplitude of the PhNR was measured from the peak of the b-wave to the PhNR trough. Mean visual field sensitivity was measured by the Humphrey Field Analyzer (HFA) program central 10-2. Spearman's coefficients were used to evaluate the correlation between the macular vessel density, PhNR amplitude, mean deviation (MD) of the HFA 10-2, retinal nerve fiber layer (RNFL) thickness, and ganglion cell complex (GCC) thickness measured by spectral domain-optical coherence tomography. Results: The mean MD of the HFA 10-2 was -2.0 ± 3.2 dB. The PhNR amplitude significantly correlated with the macular vessel density (r = 0.420, P = 0.006), but not with the MD, GCC thickness, or RNFL thickness. The macular vessel density significantly correlated with the MD (r = 0.364, P = 0.018) and RNFL thickness (r = 0.369, P = 0.016), but not with GCC thickness (r = 0.266, P = 0.089). Conclusions: Macular vessel density significantly correlated with PhNR amplitude in patients with early-stage NTG, suggesting that microvascular alterations are associated with functional changes recorded by focal ERG in very early-stage glaucoma.