Repeatability and reproducibility of scanning peripheral anterior chamber depth analyzer——the Handan Eye Study / 中华实验眼科杂志

ABSTRACT

Background Early diagnosis of primary angle-closure glaucoma (PACG) and screening or case detection of high risk population have become a major challenge in the prevention and treatment of PACG.Commonly used methods for evaluation of anterior chamber depth (ACD) and anterior chamber angle nowadays have their shortcomings.Scanning peripheral anterior chamber depth analyzer (SPAC) measures ACD and evaluates the risk of angle closure.Also,SPAC is handy,objective and noninvasive.Objective This study was to evaluate the repeatability (within-rater differences) and reproducibility (between-rater differences) of SPAC to measure anterior chamber-related parameters and agreement of SPAC to estimate occludable angle between two operators.Methods A prospective cross-sectional study was designed.Thirty subjects with shallow ACD (modified van Herick grading≤ 3 and Shaffer grading≤2) aged 35 years and older,who met the inclusion criterion were enrolled as shallow anterior chamber group and 30 age-and gender-matched normal adults (modified van Herick grading≤3 and Shaffer grading≤2)from the follow-up research of the Handan Eye Study in February 2013.After an elementary eye examination,a randomly selected eye of each subject in both groups received three consecutive SPAC measurements by each of the two examiners,respectively to obtain ACD,central corneal thickness (CCT) and corneal radius of curvature (CRC).Meanwhile,the identity of occludable angle as the numerical grade was 5 or fewer and/or the categorical grade being S or P was also obtained.The repeatability of each examiner was evaluated by the repeatability limit (RL) and the reproducibility of the two examiners was evaluated by intraclass correlation coefficient (ICC).The agreement of occludable angle estimation between two operators was evaluated using Kappa coefficient.Results The RLs percentage for ACD,CCT and CRC ranged from 0.36％ to 3.29％,and 0.90％ to 4.72％ in the normal control group and shallow anterior chamber group from operator A,and those from operator B were 0.38％ to 2.55％,and 0.51％ to 3.42％.The ICCs for ACD,CCT and C RC of SPAC were 0.966,0.859,0.989 and 0.915,0.905,0.971,respectively from operator A and operator B.The Kappa coefficients for the identity of occludable angle between two operators were 1.000 and 0.520 in the normal control group and the shallow anterior chamber group,respectively.Conclusions Measurements of the three parameters provided by SPAC in normal and shallow anterior chamber subjects show a good repeatability and reproducibility.The results of identity of occludable angle from two examiners have a good agreement for normal subjects and a moderate reproducibility for subjects with shallow ACD.