Investigation of the Variability of Anterior Chamber Scan Protocol with Cirrus High Definition Optical Coherence Tomography.

Importance: The evaluation of anterior chamber scan of Cirrus optical coherence tomography for routine clinical use.Background: To assess the variability of anterior chamber angle measurements.Design: This was a cross-sectional study.Participants: Forty subjects aged 40-80 years were included.Methods: One randomly selected eye from 40 subjects was imaged with Cirrus optical coherence tomography (Carl Zeiss Meditec, Dublin, CA) by two different operators (expert vs. non-expert) with a 15-min interval for inter-observer and intra-observer variability of image acquisition. For image grading, the angle opening distance (AOD750) and the trabecular iris space area (TISA750) of nasal and temporal quadrants were measured with a customized algorithm (ImageJ, NIH, Bethesda, MD) by two different graders in a masked and random fashion. Bland Altman analysis and intraclass correlation coefficient (ICC) were calculated.Main Outcome Measures: ICC and limit of agreements (LOA).Results: There were 15 (37.5%) eyes with closed angles. For inter-observer variability, the mean difference (95% LOA) of AOD750 for image acquisition and grading were -0.0039 mm (-0.0486, 0.0408) and 0.0011 mm (-0.0228, 0.025), respectively. The mean difference (95% LOA) of AOD750 for intra-observer variability for image acquisition and grading were 0.0013 mm (-0.0362, 0.0389) and -0.0013 mm (-0.0482, 0.0457), respectively. The ICCs were all >= 0.9. There was no significant difference in measurement variability between open and closed angles (P > 0.05).Conclusions and Relevance: Anterior chamber scan had low inter-observer and intra-observer variability in quantitative evaluation that was not affected by the angle status or the experience of an operator.