Abstract

Background: To evaluate the accuracy of automated angle closure screening software and van Herick grading (VH) compared to gonioscopy. Methods: Peripheral anterior chamber angle images of 27 eyes were taken by slit lamp biomicroscope and analyzed by automated software. The software selected region of interest and applied a light reflection extraction to detect corneal thickness (CT) and peripheral anterior chamber depth (PACD). Three observers manually counted CT (CTm) and PACD (PACDm) pixels and compared with the CT and PACD pixel counts that were obtained by the software (CTa and PACDa). Inter-rater variability was evaluated using intraclass correlation coefficient (ICC). Bland and Altman plot was used to test agreement between manual and software pixel counts. The accuracy between software and VH vs. gonioscopy was analyzed using the area under receiver operating characteristic curve (AUC). Results: Mean ± SD CTm counts were 64.6 ± 7.9, 66.2 ± 8.8, and 64.6 ± 7.5 pixels and PACDm counts were 65.8 ± 40.1, 62.7 ± 39.2, and 64.1 ± 39.7 pixels. The ICC (95% CI) for CTm and PACDm were 0.957 (0.918-0.979) and 0.997 (0.993-0.998). The limits of agreement in the Bland and Altman plot between manual and automated pixel counts for CT and PACD were -9.6 to 6.6 (mean ± SD difference: -1.5 ± 4.1) and -10.6 to 9.3 pixels (mean ± SD difference: -0.7 ± 5.1). With gonioscopy as a reference, AUCs of PACDa, PACDm, VH, CTa, and CTm were 0.818, 0.814, 0.809, 0.705, and 0.577, respectively. Conclusion: The software exhibited excellent reliability and accuracy in the measurement of PACD for angle closure screening comparable to VH grading.

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