METHODS: Totally 52 patients(100 eyes)over 40 years old were randomly selected from our outpatient department from June 2018 to January 2019.Their anterior chamber depth were examined by the methods of Van Herick method and the improved method to sort out peripheral anterior chamber depth are less than or equal to 1/3 CT and more than 1/4 CT and peripheral anterior chamber depth are less than or equal to 1/4 CT. Van Herick's anterior chamber depth inspection method and improved anterior chamber depth inspection method were checked for consistency, and then gonioscopic inspection and UBM inspection under darkroom were performed to check whether the peripheral angle was closed. In order to know whether there was any difference between gonioscopic and UBM inspection for angle closure, the consistency of the two verification results was checked.

RESULTS: Peripheral anterior chamber depth are less than or equal to 1/3 CT and more than 1/4 CT by the methods of Van Herick, the positive incidence of angle closure in angioscopy and ultrasound biomicroscopy are 39% and 43% respectively, Peripheral anterior chamber depth are less than or equal to 1/3 CT and more than 1/4 CT by the improved methods, the positive incidence of angle closure in angioscopy and ultrasound biomicroscopyare 46% and 42% respectively. In the patients whose peripheral anterior chamber depth checked by angioscopy and ultrasound biomicroscopy is less than or equal to 1/4 CT estimated by Van Herick method, the positive rate of angle closure was 67% and 89%, respectively. In the patients whose peripheral anterior chamber depth checked by angioscopy and ultrasound biomicroscopy is less than or equal to 1/4 CT estimated by the improved method, the positive rate of angle closure was 67% and 89%, respectively. The consistency test of the Van Herick method and the improved method showed good consistency(Kappa value: 0.85), when peripheral anterior chamber depth are less than or equal to 1/3 CT and more than 1/4 CT. peripheral anterior chamber depth(>1/4 CT), and good consistency(Kappa value: 0.83)when estimating peripheral anterior chamber depth ≤1/4 CT. According to the consistency test of the results of angioscopy and ultrasound biomicroscopy, when the Van Herick method estimated the depth of peripheral anterior chamber are less than or equal to 1/3 CT and more than 1/4 CT, the consistency was general(Kappa value: 0.73). When the Van Herick method estimated the depth of peripheral anterior chamber is less than or equal to 1/4 CT, the consistency was general(Kappa value: 0.40). According to the consistency test of the results of angioscopy and ultrasound biomicroscopy, when the improved method estimated the depth of peripheral anterior chamber are less than or equal to 1/3 CT and more than 1/4 CT, the consistency was good(Kappa value: 0.75). When the improved method estimated the depth of peripheral anterior chamber is less than or equal to 1/4 CT, the consistency was poor(Kappa value: 0).

CONCLUSION: The slit lamp anterior chamber depth examination has a certain false negative rate in estimating the angle closure in the population, but its accuracy is high, and it is still suitable for the preliminary examination of estimating the angle closure.