Systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio levels are associated with keratoconus.

Purpose: The aim of this study was to assess the systemic immune-inflammation index (SII) levels, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) in patients with keratoconus (KC).

Methods: A total of 42 patients with KC (KC group) and 42 age- and sex-matched healthy subjects (control group) were included into this cross sectional study. Complete blood count parameters were assayed. SII, NLR, red cell distribution width (RDW), and PLR values were calculated. The SII value was calculated as follows: platelet count × (neutrophil/lymphocyte).

Results: SII, NLR, RDW, and PLR values were significantly higher in KC group compared to control group [709 ± 236 vs. 418 ± 117 (P < 0.001), 2.5 ± 0.8 vs. 1.76 ± 0.3 (P < 0.001), 14.3 ± 1.6% vs. 12.9 ± 0.54% (P < 0.001), and 143 ± 36 vs. 106 ± 23 (P < 0.001), respectively]. Using the receiver operating characteristics (ROC) curve analysis to predict KC, the highest area under the curve (AUC) was determined SII (0.846 for SII, 0.778 for NLR, and 0.796 for PLR).

Conclusion: SII, NLR, RDW, and PLR levels were significantly increased in patients with KC. This study supports the idea that several inflammatory pathways may play important role in the pathogenesis of this disorder. SII may be much better marker than NLR and PLR for predicting the inflammatory status of the disease.