Intraobserver and interobserver agreement among anterior chamber angle evaluations using automated 360-degree gonio-photos

PURPOSE: To investigate the reproducibility for the iridocorneal angle evaluations using the pictures obtained by a gonioscopic camera, Gonioscope GS-1 (Nidek Co., Gamagori, Japan). METHODS: The pragmatic within-patient comparative diagnostic evaluations for 140 GS-1 gonio-images obtained from 35 eyes of 35 patients at four ocular sectors (superior, temporal, inferior, and nasal angles) were conducted by five independent ophthalmologists including three glaucoma specialists in a masked fashion twice, 1 week apart. We undertook the observer agreement and correlation analyses of Scheie’s angle width and pigmentation gradings and detection of peripheral anterior synechia and Sampaolesi line. RESULTS: The respective Fleiss’ kappa values for the four elements between manual gonioscopy and automated gonioscope by the glaucoma specialist were 0.22, 0.40, 0.32 and 0.58. Additionally, the respective intraobserver agreements for the four elements by the glaucoma specialist each were 0.32 to 0.65, 0.24 to 0.71, 0.35 to 0.70, and 0.20 to 0.76; the Fleiss’ kappa coefficients for the four elements among the three glaucoma specialists were, respectively, 0.31, 0.38, 0.31, and 0.17; the Fleiss’ kappa coefficients for the angle width and pigmentation gradings between the two glaucoma specialists each were 0.30 to 0.35, and 0.29 to 0.43, respectively. Overall, the Kendall’s tau coefficients for the angle gradings reflected the positive correlations in the evaluations. CONCLUSION: Our findings suggested slight-to-substantial intraobserver agreement and slight-to-fair (among the three) or fair-to-moderate (between the two each) interobserver agreement for the angle assessments using GS-1 gonio-photos even by glaucoma specialists. Sufficient training and a solid consensus should allow us to perform more reliable angle assessments using gonio-photos with high reproducibility.