To compare the diagnostic accuracy of swept-source anterior segment optical coherence tomography (AS-OCT) with gonioscopy in detecting angle closure among narrow-angle suspected eyes. A total of 125 eyes determined narrow anterior chamber angles suspected by Van Herick's technique grade 0, 1, or 2 were recruited. AS-OCT was undergone before any contact procedure. Intraocular pressure (IOP) measurements using applanation tonometry and gonioscopy were performed, respectively. AS-OCT images were blindly interpreted by 3 glaucoma specialists, involving both qualitative assessments at 0, 90, 180, and 270 degrees and quantitative analysis using iris-trabecular contact (ITC) index. The sensitivity and specificity of AS-OCT, compared with gonioscopy-the gold standard for identifying anterior chamber angle closure-were calculated. The mean age was 61±12.9 years, and females constituted 67.6%. Eyes classified by Van Herick's technique as grade 0, 1 and 2 were 16%, 58.40%, and 25.60%, respectively. Closed-angle identified by gonioscopy and AS-OCT were 100 eyes (80%) and 102 eyes (81.60%), respectively. The sensitivity and specificity of AS-OCT in detecting angle-closure were 92.16% (95% CI, 87.44-96.87) and 73.91% (66.22-81.61), respectively. For angle-closure identified by ITC index ≥ 55%, sensitivity was 86.36% (77.53-95.20) and specificity was 92.86 (86.23-99.49). The inter-observer agreement of gonioscopy was moderate (Kappa = 0.55), while the intra-observer and inter-observer agreement of AS-OCT was substantial (Kappa = 0.71-0.80 and Kappa = 0.69, respectively). AS-OCT enables a contactless qualitative and quantitative assessment of angle-closure in narrow-angle suspected eyes, demonstrating high sensitivity, acceptable specificity, and good inter-observer and intra-observer reliability.