Primary angle-closure glaucoma (PACG) is the most common type of glaucoma in China.A screening to identify the possible angle closure is important in the prevention and treatment of PACG.

This study was to determine the characteristics and the optimal parameters measured by the scanning peripheral anterior chamber depth analyzer (SPAC) in the screening of occludable angle of a sample of adult Chinese population.

A cross-sectional study was performed in Handan from February to April in 2013.One hundred and eighty Chinese adults were enrolled with the age of 40 years and older and acceptable criteria during 5-year following-up duration of the Handan Eye Study.Routine eye examinations were carried out in all subjects under the informed consent, including visual acuity, optometry, anterior ocular segment examination under the slit lamp microscope, and then SPAC measurement and gonioscopy were performed in a dark room.Occludable angle was defined as posterior trabecular meshwork being invisible in ≥180° range under the static gonioscope.Occludable angle by SPAC was estimated using available central chamber depth (ACD) and a combined indicator, numerical grade was 5 or fewer and/or the categorical grade was S or P, separately.Receiver operating characteristic (ROC) curve was calculated to assess the performance of these parameters in detecting eyes with occludable angle for the population-based sample, and area under curve (AUC) was drown to compare the screening efficiencies between available ACD and combined indicator.

In 180 subjects, occludable angles were found in 62 and open angles were in 118.Compared to the subjects with open angle, the subjects with occludable angle showed the older age (P<0.001), more females (P<0.05), lower visual acuity (P<0.001), greater hyperopic diopter (P<0.05), smaller ACD value (P<0.001) and shorter axial length(P<0.001). In eyes with occludable angle by using SPAC, the ACD showed an AUC of 0.832.Using a cutoff of 2.7 mm for ACD, the sensitivity and specificity were 85.48% and 68.64%, and under the cutoff of 2.8 mm, the sensitivity and specificity was 90.32% and 61.02%, respectively.For the combined parameters, the sensitivity and specificity was 62.90% and 90.68%, respectively and the AUC was 0.768.

When gonioscopy is used as a reference, a cutoff of 2.8 mm ACD by SPAC shows the highest sensitivity for the screening of occludable angle in Chinese population.

Angle-closure glaucoma/screening; Occludable angle; Cross-sectional studies; Scanning peripheral anterior chamber depth analyzer