Abstract
Purpose :
Anterior segment optical coherence tomography (AS-OCT) has the potential to guide diagnosis and management of angle closure glaucoma. The number of images to accurately characterize anatomical variations in angle closure glaucoma eyes is unknown. This study evaluates the number of AS-OCT images required to capture variations in mean and range of parameter measurement values in angle closure eyes.
Methods :
Subjects with gonioscopic angle closure, defined as three or more quadrants in which pigmented trabecular meshwork could not be visualized, were recruited from the Chinese American Eye Study (CHES), a population-based study of Chinese Americans in Los Angeles, CA[BX1] . 32 radial AS-OCT images from one eye per subject were analyzed. Angleopening distance (AOD), angle recess area, trabecular iris space area, iris area, iris curvature, lens vault, anterior chamber width (ACW), and anterior chamber areawere measured. To evaluate the effect of number of images, the mean and range of measurement values from 1, 2, 4, 8, and 16 images were compared to values measured from 32 images.
Results :
40 eyes from 40 subjects were analyzed. Deviation from the 32-image mean was 0.8-18.6% for 1, 0.1-6.1% for 2, 0.0-5.9% for 4, 0.0-3.0% for 8, and 0.0-1.7% for 16 images. Deviation from the 32-image range was 54.7-100% for 1, 17.4-77.6% for 2, 14.0-54.3% for 4, 0.0-38.1% for 8, and 0.0-22.9% for 16 images.
Conclusions :
Analyzing multiple AC-OCT images provides closer estimates of 32-image mean and range of measurements values of various anterior segment parameters among angle closure eyes. Measurements from 2 images are enough to approximate the mean, which is fewer than in open angle eyes. Conversely, measurements from 8 or 16 images are required to capture most of the range, which is more than open angle eyes and likely due to increased noise among AS-OCT measurements in angle closure eyes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.