AIM: To investigate the relationship between the levels of interleukin-6(IL-6)and IL-2 in aqueous humor and the severity of optic nerve injury in patients with primary open-angle glaucoma(POAG), and to construct a decision tree model for the severity of optic nerve injury in POAG patients.

METHODS: A prospective study was conducted on 107 patients(107 eyes)with POAG who were admitted to the hospital from May 2021 to October 2023. According to the mean defect(MD)value, the degree of optic nerve injury was judged and divided into three groups: mild, moderate and severe. The general data, IL-6 and IL-2 levels in aqueous humor of patients with different severity of optic nerve injury were compared, and the correlation between the levels of IL-6 and IL-2 in aqueous humor and the severity of optic nerve injury in POAG patients was analyzed. Multivariate Logistic regression analysis was used to test the influencing factors of the severity of optic nerve injury in POAG patients, and the decision tree model was constructed based on influencing factors.

RESULTS: The proportion of patients with hypertension, intraocular pressure and binocular intraocular pressure difference in the severe group was higher than that in the mild and moderate groups, and the levels of IL-6 and IL-2 in the aqueous humor were significantly lower than those in the mild and moderate groups(all P<0.05). The levels of IL-6 and IL-2 in aqueous humor of POAG patients were negatively correlated with the severity of optic nerve injury(r=-0.361, -0.358, all P<0.001). Hypertension, intraocular pressure, binocular intraocular pressure difference, IL-6 and IL-2 levels in aqueous humor were independent factors affecting the degree of optic nerve injury in POAG patients(all P<0.05). Based on the above factors, a decision tree model was constructed, and three explanatory variables of IL-6, IL-2 levels in aqueous humor and hypertension were screened out. Among them, IL-2 level in aqueous humor was the most important root node variable and the most important predictor. The AUC of the decision tree model was 0.710(95% CI: 0.599-0.820, P=0.001), the sensitivity was 0.581, the specificity was 0.737, and the Youden index was 0.318, with a high predictive value.

CONCLUSION: The levels of IL-6 and IL-2 in aqueous humor were significantly correlated with the severity of optic nerve injury in POAG patients. The decision tree model based on hypertension, intraocular pressure, binocular intraocular pressure difference, IL-6 and IL-2 levels in aqueous humor has a high evaluation value for the severity of optic nerve injury in POAG patients.