Evaluation of Potential Pain Biomarkers in Saliva and Pain Perception After Corneal Advanced Surface Ablation Surgery

PURPOSE: To evaluate the evolution of a set of proposed pain biomarkers in the saliva of subjects following Advanced Surface Ablation (ASA), in order to determine their validity as objective pain measures. METHODS: A multicenter, prospective, and descriptive study was carried out to assess the variations between biomarkers and perceived pain. The Inclusion criteria were healthy subjects who underwent a bilateral, alcohol-assisted surface ablation with epithelial removal (ASA). Pain intensity before and after surgery was assessed by Visual Analog Scale (VAS) and the Numeric Pain Rating Scale (NPRS). Cortisol, sAA, sIgA, testosterone, and sTNFαRII were assayed at four-time points (V0, baseline; V1, pre-surgery; V2, 1 hr post-surgery, and V3, 72 hrs post-surgery). Comorbidities and Hospital Anxiety and Depression (HADS) questionnaires were administrated before and at 6 hrs after the surgery. All patients were treated with cold patches, topical steroids, topical cold antibiotics, and benzodiazepines after ASA surgery. A descriptive analysis of biomarkers and pain intensity evolution and the agreement between biomarkers and pain was performed. RESULTS: Concentration of sIgA and sTNFαRII post-surgery was significantly higher at each visit compared to baseline (p-value: 0.053, p-value: <0.001, respectively). Relations between VAS scale score and putative biomarker variations were not statistically significant except for the sIgA but only at visit 0 (p-value: 0.024). The HADS questionnaire showed anxiety scores between 0 and 7 in all patients before and at 6 hrs after surgery. CONCLUSION: In this study, sIgA and sTNFαRII are the two potential biomarkers that present correlation with the VAS and these salivary substances showed acceptable levels of reproducibility in healthy subjects.