Red Cell Distribution Width (RDW) and Complete Blood Cell Count-Derived Measures in Non-Arteritic Anterior Ischemic Optic Neuropathy

Purpose: To assess the role of complete blood cell count (CBC) dimensional indices and CBC-derived measures in non-arteritic anterior ischemic optic neuropathy (NA-AION). Methods: In this retrospective case-control survey, 37 newly diagnosed NA-AION patients and 37 sex- and age-matched cataract controls were enrolled in 2017-2018. On the same day of NA-AION diagnosis, a blood sample was collected and CBC was determined using an automatic blood counter. CBC dimensional indices, such as mean platelet volume (MPV) and red cell distribution width (RDW), and CBC-combined indices, including neutrophil/lymphocyte ratio (NLR), derived NLR [dNLR = neutrophils/(white blood cells - neutrophils)], and platelet/lymphocyte ratio (PLR), were evaluated. Erythrocyte sedimentation rate (ESR) was also measured. Results: Mean platelet count, median MPV, RDW, NLR, and dNLR were 221±48 x 109/L, 8.2 fL (IQR=7.6-8.9), 13% (IQR=12-14.5), 2.50 (IQR=1.77-3.06), and 1.73 (IQR=1.31-2.07) in NA-AION patients and 248±56 x 109/L, 7.60 fL (IQR=7.05-8.25), 12% (IQR=11.6-13), 1.95 (IQR=1.43-2.49) and 1.36 (IQR=1.07-1.69) in controls. NA-AION patients showed significantly lower platelet count (p=0.03) and significantly higher median values of MPV (p=0.01), RDW (p=0.015), NLR (p=0.03), and dNLR (p=0.01). Multivariate logistic regression models disclosed a significant correlation only between higher levels of RDW and NA-AION (p≤0.05). The attributable risk of the association between NA-AION and RDW was 33%. Conclusions: Results suggest that RDW may be somehow involved in the pathogenesis of NA-AION. However, high-quality cohort studies are warranted to confirm whether, or not, an altered RDW may be considered a potential biomarker of this vascular disorder affecting the optic nerve.