Purpose:
To compare the quantitative analysis of the anterior-chamber in images obtained with 2 anterior-segment optical coherence tomography (AS-OCT) devices.
Methods:
Prospective cross-sectional observational study with 101 consecutive subjects over 40 years old recruited from a Singapore hospital. Image acquisition using Visante-OCT (Carl Zeiss Meditec, Dublin/USA) and SL-OCT (SL-OCT, Heidelberg Engineering, Heidelberg/Germany) was performed under the same room lighting conditions by a single operator in the same order. A single masked examiner with glaucoma subspecialty training performed the quantitative analysis on horizontal scans (nasal/temporal angles) using custom-built software included in the SL-OCT device and Zhongshan Angle Analysis Program (ZAAP, Guangzhou, China) for Visante-OCT images. The following parameters were assessed: angle-opening distance (AOD), trabecular-iris space area (TISA), central anterior-chamber depth (ACD), scleral-spur to scleral-spur distance (SpurD) and pupil diameter.
Results:
The scleral-spur was not detectable in 25 (25%) eyes imaged by SL-OCT and in 23 (23%) eyes imaged by Visante-OCT. The mean of differences (bias) was 6µm for ACD, 106µm for SpurD, and ranged from 88~110µm for AOD, and from 30~51µm2 for TISA. AOD and TISA values measured on SL-OCT images were significantly higher than the ones measured by Visante-OCT (p<0.001). The pupil diameter was significantly higher in Visante-OCT images (p<0.001).
Conclusions:
Difficulty in detecting the scleral-spur precluded the quantitative analysis of the anterior-chamber in more than 20% of the images obtained with either AS-OCT devices. When compared to Visante-OCT, SL-OCT tended to measure higher values for AOD and TISA. The use of visible light to aid the proper location of the scanning beam in SL-OCT may help explain these discrepancies.Figure: Quantitative analysis of anterior-segment from the same patient - Visante-OCT image (top), SL-OCT image (bottom)
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior chamber