To establish the normal reference interval of the intracranial pressure gradient in the Chinese population so as to provide a standard for the establishment of open-angle glaucoma diagnosis and treatment new system based on the Intraocular and Intracranial Pressure Gradient (ONPG).

Cross-sectional study, 200 patients (97 males and 103 females) who underwent lumbar puncture from August 2010 to August 2019 in the Department of Neurology, Beijing Tongren Hospital, Capital Medical University were selected as subjects. Intraocular pressure, intracranial pressure and basic parameters were performed in all patients. The gender was described using frequency distribution and percentage method, and the age, height, weight, intraocular pressure, intracranial pressure, MAP, BMI and ONPG were described using. Markov Chain Monte Carlo Simulation (MCMC) was used to perform multiple interpolation on the missing value. The range of reference values was determined using the 95% quantile method. One-way ANOVA was used for comparison between multiple groups of continuous quantitative data, and two independent samples were used for pairwise comparison.

According to the parameters, the normal reference interval of intraocular pressure, intracranial pressure and the ONPG is 9.015 mmHg to 20.265 mmHg, 6.179 mmHg to 14.921 mmHg and -2.987 mmHg to 11.047 mmHg. The reference interval for clinical diagnosis and treatment of ONPG is 0.423 mmHg to10.508 mmHg. Grouped according to age, Age < 30 was the youth group, 30 ≤ Age ≤ 50 was the middle age group, Age>50 was the elderly group.The reference interval of ONPG in the youth group is -2.968 mmHg to 9.028 mmHg, in the middle age group is -2.466 mmHg to 11.606 mmHg, in the elderly group is -2.466 mmHg to 11.606 mmHg.There was no significant difference in ONPG between the three groups (F=2.041, P>0.05). Grouped according to gender, male reference interval of ONPG is -2.769 mmHg to 10.089 mmHg, female reference interval of ONPG is -3.137 mmHg to 11.877 mmHg.There was no significant difference in ONPG between the two groups(t=-1.413, P>0.05). Grouped according to BMI, BMI<21 kg/m² was the low weight group, BMI 21 kg/m²<BMI<23 kg/m² was the normal weight group, BMI ≥ 23 kg/m² was the overweight group. The reference interval of ONPG in low weight group is -1.437 mmHg to 11.577 mmHg, in normal weight group is -3.646 mmHg to11.026 mmHg, in overweight group is -3.947 mmHg to 10.087 mmHg.There was a statistically significant difference in ONPG between different BMI groups (F=6.109, P<0.05).

The reference interval for clinical diagnosis and treatment of ONPG is (0.423 mmHg to 10.508 mmHg), which can be used as a new indicator for clinical diagnosis and treatment of open-angle glaucoma. Provide a new practice and research direction for further study of the etiology and individualized treatment of open-angle glaucoma.