Comparison of different modes in optical coherence tomography and ultrasound biomicroscopy in anterior chamber angle assessment.

PURPOSE: To compare anterior chamber angle width measurements by low and high-resolution anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). PATIENTS AND METHODS: Thirty-six eyes of 32 patients with gonioscopically narrow angles from a university-based glaucoma clinic were recruited in the study. All subjects received AS-OCT {in "Anterior Segment Single" mode [low-resolution optical coherence tomography (LOCT)] and "High-resolution Cornea" mode [high-resolution optical coherence tomography (HOCT)]} and UBM examination in 1 or both eyes. Angle opening distance (AOD) and angle recess area of temporal (t) and nasal (n) quadrants were assessed using the customized software on each type of image. Angle measurements from UBM, LOCT, and HOCT images were compared; intraobserver and interobserver measurement reproducibility for each type of image was also evaluated. RESULTS: Thirty-three eyes of 29 patients were available for analysis. No significant differences were found between LOCT and UBM in the measurement of t-AOD (P=0.350), n-AOD (P=0.106), and n-angle recess area (P=0.360). HOCT measurements were significantly larger than both LOCT and UBM for all parameters (all, P<0.05). HOCT images had better interobserver and intraobserver measurement reproducibility than UBM images. CONCLUSIONS: LOCT is similar to UBM for most of the studied angle measurements. HOCT tends to give larger measurements than both LOCT and UBM. AS-OCT measurements were more reproducible than those from UBM.