Ultrasound biomicroscopy (UBM) had played the dominant role in objective imaging of the anterior chamber angle until anterior segment optical coherence tomography (ASOCT) was introduced in 2003. Although ASOCT provides a higher axial resolution (18 μm in commercial ASOCT device vs. 25 μm in 50 MHz UBM), this is not ASOCT’s major advantage. The true advantage of ASOCT is its non-contact scanning method that is performed in the sitting position, whereas UBM requires a plastic or silicone eyecup to hold a coupling medium (methyl cellulose or saline solution), which requires supine position scanning. Therefore, when it comes to patients’ compliance and comfort in daily clinical settings, ASOCT is a clear winner. However, from the clinicians’ viewpoint, the first and most important question is whether ASOCT provides clinically useful information like that which made UBM famous and popular (eg, angle opening distance, angle recess area, trabecular-iris angle, etc).

Li et al’s1 study …