Characteristics and reproducibility of anterior chamber angle assessment by anterior-segment optical coherence tomography

Abstract

ABSTRACT.Purpose: To evaluate the basic characteristics and reproducibility of anterior chamber angle (ACA) measurements determined by anterior-segment optical coherence tomography (AS-OCT) in open-angle and primary angle closure suspect (PACS) patients. Methods: Thirty-nine open-angle and 18 PACS patients were imaged for ACA by AS-OCT. Subjects underwent imaging of the nasal, temporal and inferior ACA under conditions of constant light, and darkness. For analysis, we used three ACA parameters handled by the Visante OCT software: angle opening distance at 500 lm (AOD 500 ), trabecular-iris space area at 500 lm (TISA 500 ) and angle recess area at 500 lm (ARA 500 ). For determination of inter-session reproducibility, a single well-trained operator (D.Y.K.) scanned all patients at two different visits. For determination of inter-operator variability, a second operator (S.B.P.) acquired another set of images independently. Three sets of images were acquired at least 24 hour apart. Results: All parameters were significantly different when measured both in light and darkness, and in the nasal and temporal quadrants. There were no significant differences between the left and right eyes in the three ACA parameters in all quadrants. The temporal angle was wider than the nasal and inferior angles. All parameters of the nasal, temporal angles had excellent inter-session and inter-operator reproducibility [intra-class correlation coefficient (ICC) 0.796-0.981], but these values were slightly lower for inferior angle measurements in both open-angle and PACS groups. Conclusion: AS-OCT provides quantitative and reproducible assessment of ACA. Reproducibility was lower in the inferior angle compared with the nasal and temporal angles, perhaps because of variable placement of the scleral spur.

Reproducibility of Anterior Segment Angle Metrics Measurements Derived From Cirrus Spectral Domain Optical Coherence Tomography

“…We did not assess the reproducibility of measurements in other quadrants in this analysis. Although our results were comparable to some of the best results from prior studies, 24,25 it should be noted that our metrics were SL-based rather than scleral spur-based. SL has been shown to be easier seen than the Scleral spur on SD-OCT, 22,26,27 being identified in 95% of ACA scans, 17 meaning it may represent a better anatomic landmark for assessing ACA.…”

Anterior Chamber Angle Assessment by Anterior-segment Optical Coherence Tomography After Phacoemulsification With or Without Goniosynechialysis in Patients With Primary Angle Closure Glaucoma

“…12 For each eye, 6 AS-OCT cross-sectional images of the ACA were obtained at the angles of 90 (ACAngle-90) and 270 degrees (ACAngle-270), 60 (ACAngle-60) and 240 degrees (ACAngle-240), 30 (ACAngle-30) and 210 degrees (ACAngle-210), 0 (ACAngle-0) and 180 degrees (ACAngle-180), 330 (ACAngle-330) and 150 degrees (ACAngle-150), and 300 (ACAngle-300) and 120 degrees (ACAngle-120), respectively. After acquisition, the scanned images were to be processed by a customized software ("dewarping" software), [13][14][15] which compensated for index of refraction transition at the air-tear interface and the different group indices in air, cornea, and aqueous humor to correct the physical dimensions of the images.…”

Comparison of the anterior ocular segment measurements using swept-source optical coherent tomography and a scanning peripheral anterior chamber depth analyzer

“…We did not investigate examiner-dependent variability and the reproducibility of measurements, although many previous papers report a high degree of reproducibility [14,21,22,[31][32][33]. SPAC is considered to be operator independent to a large extent [14], but the SS-OCT measurements are not automatic.…”