Normal Ranges of Serum Hemoglobin Affect Macular Vessel Density of Optical Coherence Tomography Angiography

Purpose: To investigate whether normal ranges of serum hemoglobin (Hb) affect macular vessel density (mVD) constructed by optical coherence tomography (OCT) angiography (OCTA), and whether the correlation between mVD and ganglion cell-inner plexiform layer thickness (GCIPLT) is affected by Hb in a normal range.Methods: A total of 50 glaucomatous eyes and 59 control eyes were prospectively recruited.OCT and OCTA were conducted and mVD for superficial, deep, choriocapillary and choroid layers were calculated.Serum Hb levels were obtained within 2 weeks of OCTA scans.Results: Glaucomatous eyes (61.4 ± 13.4 years old, 68.0% males) showed significantly lower mVD in superficial (24.2% ± 2.7% vs. 26.2%± 3.0%, p < 0.001) and deep (29.7% ± 2.4% vs. 31.1% ± 1.2%, p < 0.011) layers in comparison to control.Multivariate linear regression analysis revealed that mVD was significantly correlated with Hb after adjustment for confounders in the superficial (glaucoma: R 2 = 0.332, p = 0.012; control: R² = 0.442, p = 0.001), deep (glaucoma: R 2 = 0.336, p = 0.005; control: R 2 = 0.362, p = 0.008) layers for both glaucoma and controls.Adjusting for Hb improved the goodness of fit of relationships between GCIPLT and superficial (AIC 336: R 2 = 0.405, p = 0.004) and deep mVD (AIC 317: R 2 = 0.643, p < 0.001) among glaucoma patients (before adjustment, AIC 341 superficial; AIC 326 deep).Conclusions: Normal ranges of Hb affect mVD constructed by OCTA.Considerations for hemodynamic status may improve interpretations of macular vascular changes in glaucoma patients.