Anterior Chamber Angle Measurement with Anterior Segment Optical Coherence Tomography (OCT) - A Comparison Between Slit Lamp OCT and Visante OCT

¹ Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, 3/F, Chinese University of Hong Kong Eye Center, Hong Kong Eye Hospital, 147K Argyle Street, Kowloon City, nil, Hong Kong; Ophthalmology, Hamilton Glaucoma Center, 9500 Gilman Drive, La Jolla, California, 92093, United States
² Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon City, Hong Kong
³ Ophthalmology, UCSD Glaucoma Center, La Jolla, California, United States
⁴ Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
⁵ Ophthalmology & Visual Sciences, Chinese University of Hong Kong, Kowloon, Hong Kong

^* To whom correspondence should be addressed. E-mail: cksleung{at}gmail.com.

	Abstract

PURPOSE: To compare anterior chamber angle measurements obtained from two anterior segment optical coherence tomography instruments and to evaluate their agreements and inter-observer reproducibility. MEHTODS: Forty-nine eyes from 49 healthy normal subjects were recruited. The anterior chamber angle was imaged with the Visante anterior segment optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA) and the slit-lamp OCT (SLOCT, Heidelberg Engineering, GmbH, Dossenheim, Germany) on one randomly selected eye in each subject and measured by 2 independent observers. The angle opening distance (AOD 500), the trabecular-iris angle (TIA 500) and the trabecular-iris space area (TISA 500) at the nasal and temporal angles were measured. The agreements between SLOCT and Visante OCT measurements and the inter-observer reproducibility were evaluated. RESULTS: The mean nasal / temporal anterior chamber angles measured by Visante OCT and SLOCT were 527+/-249µm / 572+/-275µm (AOD), 0.180+/-0.091mm2 / 0.193+/-0.102mm2 (TISA), 38.1+/-12.3°/ 39.6+/-13.2° (TIA) and 534+/-234µm / 628+/-254µm (AOD), 0.191+/-0.089mm2 / 0.217+/-0.093mm2 (TISA), 37.8+/-10.1°/40.6+/-10.7° (TIA), respectively. No significant difference was found between Visante OCT and SLOCT measurements except the temporal TISA (p=0.034). The inter-observer coefficient of variation ranged between 4.4-7.8% for Visante OCT and 4.9-7.0% for SLOCT. The spans of 95% limits of agreement of the nasal / temporal angle measurements between Visante OCT and SLOCT were 437µm / 531µm, 0.174mm2 / 0.186mm2, and 25.3° / 28.0° for AOD, TISA and TIA, respectively. CONCLUSIONS: Although Visante OCT and SLOCT demonstrate high inter-observer reproducibility for anterior chamber angle measurements, their agreement is poor.

Key Words: Anterior segment optical coherence tomography, anterior chamber angle, reproducibility, Visante OCT, SLOCT

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