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Repeatability and reproducibility of anterior chamber angle measurement with anterior segment optical coherence tomography

Haitao Li¹, Christopher Kai Shun Leung^1,2, Carol Yim Lui Cheung¹, Lee Wong¹, Chi Pui Pang¹, Robert Neal Weinreb² and Dennis Shun Chiu Lam¹

¹ Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
² Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, USA

Correspondence to:
Dr Christopher Kai Shun Leung, Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong; tlims00{at}hotmail.com

Aim: To evaluate the repeatability and reproducibility of anterior chamber angle measurement obtained by anterior segment optical coherence tomography.

Methods: Twenty-five normal subjects were invited for anterior chamber angle imaging with an anterior segment optical coherence tomography (OCT) on one randomly selected eye in three separate visits within a week. Each eye was imaged three times under room light (light intensity = 368 lux) and three times in the dark during the first visit. In the subsequent visits, each eye was imaged once in the light and once in the dark. The angle opening distance (AOD 500) and the trabecular–iris angle (TIA 500) were measured by a single observer. Only the nasal angle was analysed. Intrasession and intersession within-subject standard deviation (Sw), precision (1.96xSw), coefficient of variation (CVw) (100xSw/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility.

Results: For intrasession repeatability, the Sw, precision, CVw and ICC of AOD/TIA were 45 µm/2.4°, 88 µm/4.7°, 5.8%/4.8% and 0.97/0.95 in the light; and 45 µm/2.1°, 88 µm/4.2°, 7.0%/5.0% and 0.98/0.97 in the dark. For intersession reproducibility, the Sw, precision, CVw and ICC of AOD/TIA were 79 µm/3.5°, 155 µm/6.8°, 10.0%/7.0%, 0.91/0.89 in the light; and 64 µm/3.4°, 124 µm/6.6°, 9.9%/7.8% and 0.95/0.92 in the dark.

Conclusions: The anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions with good repeatability and reproducibility.

Abbreviations: AOD, angle opening distance; CVw, coefficient of variation; ICC, intraclass correlation coefficient; OCT, optical coherence tomography; Sw, within-subject standard deviation; TIA, trabecular–iris angle; UBM, ultrasound biomicroscopy

Competing interests: None declared.

Funding: CL has received an honorarium from Carl Zeiss Meditec for a conference presentation. RW has received research support in the form of instruments from Carl Zeiss Meditec. He has also been a consultant for Carl Zeiss Meditec.

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