Neutrophil-to-Lymphocyte Ratio and Non-arteritic Anterior Ischemic Optic Neuropathy

Letter to the Editor,

In the recent issue of the Balkan Medical Journal, we read with interest the article by Polat et al. (1): “Neutrophil-to-Lymphocyte Ratio as a Marker in Patients with Non-arteritic Anterior Ischemic Optic Neuropathy”. We wanted to specify some matters and our thoughts related to this article.

First of all, as mentioned in the article, neutrophil-to-lymphocyte ratio (NLR) can be affected in patients with systemic diseases and it is a shortcoming that the patients in this study were not evaluated for the existence of other systemic diseases except for diabetes mellitus and hypertension, while patients were excluded from study in the presence of heart disease, coronary artery disease, liver disease or malignancy. In addition, infections, even if localized, can affect neutrophil count, lymphocyte count and therefore NLR (2). It has been reported that NLR is a more powerful predictor of infection than simple white blood cell counts (3). As a result, patients, both in the study group and the control group, should be evaluated for the presence of any infection in the period of laboratory testing aside from systemic diseases. We think that this is another drawback of this study resulting from retrospective analysis.

Secondly, we believe that selecting a control group containing only cataract patients was another drawback which might have affected the results. Although to the best of our knowledge there has been no study investigating the association between cataracts or the etiological causes and NLR, as a theory, cataracts or more likely the etiological causes resulting in cataracts might affect NLR. For this purpose, it would be better that age- and gender-matched individuals without cataracts, any infection or systemic disease and some patients with only diabetes mellitus and/or hypertension had been selected as control groups 1 and 2. This may also be another drawback resulting from the retrospective nature of the analysis.

Lastly, the authors mentioned that best corrected visual acuity (BCVA) at the time of diagnosis and in the third month was significantly and negatively correlated with NLR (r=−0.406, p=0.008; r=−0.408, p=0.028, respectively). Due to this finding, they discussed whether NLR may be a predictive factor or marker in the diagnosis of non-arteritic anterior ischemic optic neuropathy. However, when interpreting the results in Spearman correlation analysis, the ‘r’ value must be considered. As a result, in this study there was a statistically significant but moderate correlation between BCVA and NLR.