The Diagnostic Value of Neutrophil to Lymphocyte Ratio as an Effective Biomarker for Eye Disorders: A Meta-Analysis

The neutrophil to lymphocyte ratio (NLR) reflects a dynamic relationship between the innate (neutrophils) and adaptive (lymphocytes) cellular immune response. This systematic review and meta-analysis was conducted to critically evaluate the literature regarding the use of the NLR as a reliable means to detect several ocular disorders. Our study was registered with the PROSPERO (ID: CRD4202231485 ). Three databases, including PubMed, Embase, Scopus, and the Web of Science, were searched on September 9, 2022, with no restrictions on the article's language. Finally, 32 articles were recognized as eligible for our meta-analysis. We found that patients with eye diseases had significantly elevated levels of NLR in comparison to healthy controls (SMD=0.53, 95% CI=0.35-0.71, P < 0.001). In subgroup analysis, patients with keratoconus (SMD=0.69; 95% CI=0.33-1.05, P < 0.001), glaucoma (SMD=0.56, 95% CI=0.25-0.87, P < 0.001), pterygium (SMD=0.14; 95% CI=0.01-0.26, P < 0.001), and idiopathic epiretinal membrane (SMD=0.14; 95% CI=0.01-0.26, P < 0.001) had higher levels of NLR compared to healthy controls. However, NLR levels of patients with dry eye disease were similar to healthy controls (SMD=0.32, 95% CI=-0.49-1.13, P=0.435). It can be said that NLR is a valuable marker of systemic inflammation, which is significantly increased in many eye disorders, suggesting that inflammation plays a key role in the pathophysiology of these diseases.