Purchase this article with an account.
Ephrem Melese, Alice Chuang, Laura Baker, Lauren Blieden, Nicholas P Bell, Robert M Feldman; Sensitivity, Specificity, and Optimal Thresholds of Anterior Chamber Angle (ACA) Parameters Measured by Anterior Segment Optical Coherence Tomography (ASOCT) in Determination of Open Versus Closed Angles. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4998.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Evaluate sensitivity and specificity of ACA parameters in detecting peripheral angle closure and establish the threshold for each measurement using Swept Source Fourier Domain ASOCT images
ASOCT images of 164 participants with eyes classified by Spaeth gonioscopy as closed (A or B) or open angle (D or E) were included. All imaging was performed in the dark with the CASIA SS-1000 (Tomey, Nagoya, Japan) using angle analysis 3D mode. Images were read by an experienced masked reader using customized software, Anterior Chamber Angle and Interpretation (ACAI, Houston, TX) to identify scleral spur landmarks (SSLs). Based on the SSLs, ACAI calculated angle opening distance at 750 µm from SSL (AOD750), length of irido-trabecular contact (ITC), and trabecular-iris space area between SSL and 750 µm from SSL (TISA750) at horizontal and vertical meridians as well as area of ITC, trabecular-iris circumference volume (TICV750), an integrated TISA750, and iris volume. Logistic regression analysis was used to estimate the receiver operating characteristic (ROC) curve and area under ROC (AUROC) for each ACA parameter. The optimal threshold value for discriminating closed angle versus open angle eyes was determined by the value where sensitivity and specificity curves met.
The mean age of the participants was 55.5 years (±13.7) with 117 (71.3%) females, 86 (52.4%) White, and 41 (25%) Black. Eighty-five (51.8%) eyes had open angles on gonioscopy. AUROC and optimal threshold as well as sensitivity/specificity at the threshold for each ACA parameter are shown in Table 1. All ACA parameters except iris volume had AUROC > 0.85, and TICV750 was found to have the highest AUROC when compared with other (ACA) parameters. An estimated optimal threshold for TICV750 was 4.23 µL. It indicates that a TICV750 measurement less than 4.23 µL has a 93% chance of being closed. AUROC for iris volume was 0.51 which was no different from random classification. TICV750 and ITC area had the greatest sensistivity and specificity.
This study supports the clinical usefulness of TICV750 in the determination of angle closure. The optimal threshold level for determining angle closure using TICV750 is 4.23 µL. This may be a useful criteria for separating open from closed angles on ASOCT.
This PDF is available to Subscribers Only