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Baskaran Mani, Christine Yau, Sue-Wei Ho, Tin A Tun, Shamira Perera, Tin Aung; Comparison of time domain anterior segment OCT with swept source OCT for angle closure imaging. Invest. Ophthalmol. Vis. Sci. 2014;55(13):932.
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© ARVO (1962-2015); The Authors (2016-present)
To compare angle closure assessed by conventional time domain anterior segment optical coherence tomography (ASOCT) using 2 scans, with swept source OCT (SSOCT) using 360° anterior segment imaging, with gonioscopy as the reference standard.
ASOCT (Visante, Carl-Zeiss Meditec, Dublin) was performed in dark conditions and 2 scans (one vertical and one horizontal) were obtained for all participants. SSOCT 3-dimensional angle scans (CASIA SS-1000, Tomey Corporation, Nagoya, Japan), that obtain 128 radial scans for the entire circumference of the angle, were performed under dark conditions. Iris Trabecular Contact (ITC) index was calculated as a percentage of the angle that was closed on 16/128 SSOCT scans using in-built customized software. Qualitative assessment of angle status was also determined for all 128 SSOCT scans. Angle closure on gonioscopy was defined as non-visibility of posterior trabecular meshwork for at least 2 quadrants. Angle status in anterior segment imaging scans was considered closed if ≥50% of the frames showed angle closure as assessed by a masked clinician. Cohen’s Kappa statistics (k) and area under the receiver operating characteristic (AUC) curve analyses were performed for angle closure based on the 3 types of scan methods in comparison to gonioscopy.
Study subjects (n=126, closed angles - 31, 24.6%) were predominantly Chinese (95.2%) and female (71.4%) with a mean age of 59.5 (standard deviation, SD = 8.9) years. Agreement for angle closure diagnosis based on ASOCT (2 scans, k = 0.32) vs SSOCT 16 scans (ITC index, k = 0.39) vs SSOCT 128 scans over 360° (k = 0.32) was fair in comparison to gonioscopy . AUC for gonioscopic angle closure detection was comparable for all 3 imaging methods (ASOCT 2 scans AUC 0.72, [95% CI - 0.64, 0.80], SSOCT ITC index 16 scans AUC 0.67 [95% CI - 0.58, 0.75] and SSOCT 128 scans AUC 0.69 [95% CI - 0.60, 0.76]).
Time domain ASOCT using 2 anterior segment scans had comparable diagnostic performance to 360° SSOCT using 16 or 128 anterior segment scans, for gonioscopic angle closure diagnosis. Both methods showed moderate agreement with gonioscopy.
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