Abstract
Purpose: :
To compare anterior chamber angle width measured by anterior segment optical coherence tomography (AS-OCT) in different resolution modes and ultrasound biomicroscopy (UBM).
Methods: :
Patients in an academic glaucoma clinic who received low resolution AS-OCT (LOCT), high resolution AS-OCT (HOCT) and UBM examination from February to November of 2007, were included in this study. Eyes with completely closed angles for more than 300 degrees were excluded. All of the images were analyzed by the same customized UBM PRO 2000 software and operator. Angle opening distance at 500µm from scleral spur (AOD) and angle recess area at 750µm from the scleral spur (ARA) of temporal and nasal quadrant were assessed to quantify the angle width.
Results: :
Thirty-six eyes of 36 patients met the criteria. The mean value of parameters from UBM, LOCT and HOCT were 117.9±83.6 µm, 140.3±91.0 µm, 169.58±92.3 µm for the temporal AOD; 129.1±76.8 µm, 142.7±91.0 µm, 156.1±87.2 µm for the nasal AOD; 0.070±0.049 mm2, 0.086±0.051 mm2, 0.103±0.058 mm2 for the temporal ARA; 0.079±0.045 mm2, 0.086±0.054 mm2, 0.090±0.050 mm2 for the nasal ARA. Between LOCT and UBM, there was no significant difference for temporal AOD (P=0.12), nasal AOD (P=0.07), and nasal ARA (P=0.34) by pair-wise t-test. HOCT images had significantly larger angle measurement than both LOCT and UBM (P<0.05 for nasal and temporal AOD and temporal ARA). Compared with HOCT, LOCT showed a better correlation with UBM for all the parameters (for LOCT and UBM, r=0.871, 0.926, 0.911, and 0.912 for temporal, nasal AOD and temporal, nasal ARA; for HOCT and UBM, r=0.824, 0.814, 0.812, and 0.810 respectively; P<0.001 for all correlations).
Conclusions: :
LOCT is similar to UBM in angle width measurement for most of the studied parameters. HOCT has a good correlation with both LOCT and UBM, but tends to give a larger angle width measurement.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior chamber • imaging/image analysis: clinical