Abstract
Purpose: :
Ultrasound biomicroscopy (UBM) has been used for untouched evaluation of anterior chamber (AC) angle. Recently, anterior-segment swept-source optical coherence tomography (AS-SS-OCT) has become available for the same purpose. Compared with UBM, AS-SS-OCT can evaluate wider region of the AC in a shorter time with higher resolution. The aim of this study was to compare AS-SS-OCT with UBM for the evaluation of iridotrabecular contact (ITC), which consists of both peripheral anterior synechia (PAS) and appositional (functional) angle closure, in narrow angle eyes.
Methods: :
In 34 right eyes of 34 consecutive patients with shallow peripheral AC (2 or less with the van Herick method), gonioscopy and imagings of AC angle using AS-SS-OCT (SS-1000 CASIA, Tomey) with 128 radial scans centered on the corneal center and UBM (UD-6010, Tomey) with 4 line scans at the 12-, 3-, 6- and 9-o’clock positions were performed under dark and light conditions.
Results: :
When using UBM, in PAS-negative quadrants, prevalence of ITC was highest in superiorly, then inferiorly, then nasally, and then temporally; and in total, ITC was found in 19 (16.1%) and 47 (39.8%) of the 118 PAS-negative quadrants under light and dark conditions, respectively. In PAS-positive quadrants, though the numbers were small, the prevalence of ITC did not differ among the four quadrants; and in total, ITC was found in 12 (66.7%) and 14 (77.8%) of the 18 PAS-positive quadrants under light and dark conditions, respectively. When using AS-SS-OCT, ITC was found in 110 (93.2%) of 118 PAS-negative quadrants under light condition and in all (100%) quadrants under dark condition. In PAS-positive quadrants, ITC was found in all (100%) quadrants under both light and dark conditions.
Conclusions: :
In narrow angle eyes, ITC was found in less than 40% of the PAS-negative quadrants with UBM, while in almost all quadrants with AS-SS-OCT, suggesting a superior performance of AS-SS-OCT for untouched evaluation of peripheral AC configurations.
Keywords: anterior chamber • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)