The aim of this study is to evaluate the efficacy of matrix metalloproteinase 9 (MMP-9) in the diagnosis of dry eye.

This clinical trial was designed as a prospective double-center cross-sectional study. A total of 458 patients (458 eyes) were collected from the Department of Ophthalmology of The First People′s Hospital of Xiangyang City and the Department of Ophthalmology of Hubei National Medicine Dongfeng General Hospital from April 2023 to July 2023. The ocular surface disease index (OSDI) score, tear film rupture time of fluorescein staining (FBUT), sodium fluorescein keratoconjunctival staining score and tear secretion test (Schirmer Ⅰ) were conducted. According to the results, they were divided into dry eye group and non-dry eye group and graded by the degree of severity of dry eye group. The tear lavage fluids were collected by same standard method from all patients and detected by MMP-9 test kit. The obtained results of the MMP-9 test kit were compared with that diagnosed by traditional method, which to evaluate its diagnostic effectiveness. The positive rate of MMP-9 was calculated in patients with different severity of dry eye and the possible adverse reactions were recorded. The patient′s age, OSDI scale, FBUT, and Schirmer Ⅰ test measurement data conformed to a normal distribution, and were described as ±s, and compared by independent sample t-test for inter group. The patient′s gender and corneal staining score were described using case numbers and percentage, and compared by χ² tests and unidirectional ordered classification χ² tests for inter group. The sensitivity, specificity, positive predictive value, negative predictive value, and overall conformity rate of MMP-9 for diagnosing dry eyes in ocular surface irrigation solution were calculated. The Kappa test was used to analyze the consistency between the MMP-9 detection of eye surface irrigation solution and traditional methods for dry eye diagnosis. The detection rate of MMP-9 eye surface rinse solution for dry eyes of different severity levels was calculated, and 95% CI of each detection rate use Wilson′s partition method was calculated.

The average OSDI score, average FBUT value, and average Schirmer Ⅰ test value of patients in the dry eye group were (22.0±9.4) points, (5.8±2.2) seconds, and (7.1±6.5) mm/5 minutes, respectively. The non dry eye group patients were (4.9±1.8) minutes, (12.1±1.2) seconds, and (14.9±4.8) mm/5 minutes, respectively. The average OSDI score of dry eye patients was higher than that of non dry eye patients, and the average FBUT value and Schirmer Ⅰ test value were lower than those of non dry eye patients, with statistically significant differences (t=29.05, -38.05, -14.70; P<0.05). Among patients in the dry eye group, there were 46 cases (46 eyes), 86 cases (86 eyes), 32 cases (32 eyes), 8 cases (8 eyes), and 6 cases (6 eyes) with fluorescein sodium keratoconjunctival staining scores of 0, 1, 2, 3, and 4, respectively, accounting for 25.84%, 48.31%, 17.98%, 4.49%, and 3.37%, respectively. The fluorescein sodium keratoconjunctival staining scores of patients in the non dry eye group were both 0 points, and there was a statistically significant difference between the two groups (χ 2=291.71, P<0.05). According to the results of MMP-9 detection in ocular surface irrigation fluid, there were 183 cases (183 eyes) diagnosed with dry eyes, and 275 cases (275 eyes) diagnosed with non dry eyes. Its diagnostic sensitivity and specificity was 96.07% and 95.71%, respectively; the positive predictive value and negative predictive value was 93.44% and 97.45%, respectively; the overall conformity rate was 95.85%. According to the consistency analysis between MMP-9 detection in ocular surface irrigation solution and traditional clinical diagnostic methods, the Kappa value of the diagnostic consistency between them was 0.913 (95%CI: 0.875 to 0.951). The positive rates of MMP-9 detection in the ocular surface rinse fluid of patients with mild, moderate, and severe dry eyes were 95.68%, 100%, and 100%, respectively, and there were no adverse reactions.

The detection of MMP-9 for tear lavage fluids was reliable method with high sensitivity and specificity ratio in the diagnosis of dry eye, which could be a feasible method for the diagnosis and medication guidance of dry eye.