Abstract
Purpose :
The emerging ASOCT platforms provide non-invasive and quantifiable evaluations in anterior chamber iridocorneal angle (ACA) anatomy. Many ab-interno glaucoma surgeries, as well as, research into intracameral medication delivery are starting to rely on ASOCT. Although tremendous literature has described artifacts in posterior segment OCT, few if any have described in detail the artifacts seen in ASOCT. The purpose of our study was to quantify the types of imaging artifacts that are commonly seen in ACA evaluation of glaucoma patients.
Methods :
The ASOCT images of both eyes of 2541 glaucoma patients were reviewed at Doheny Image Reading Center (DIRC). More than one ASOCT images were obtained using either spectral-domain ASOCT instrument (Zeiss Cirrus, Heidelberg Spectralis and Optovue RTVue) or time-domain ASOCT (Visante). ‘Poor quality’ images reported by the DIRC were independently analyzed by two certified DIRC evaluators. The artifacts that both evaluator agreed on were summarized. Observed causes of poor image quality were classified into 2 major groups: imaging technique flaws and artifacts of the image.
Imaging technique flaws include: scan beyond targeted limbus (1); lack of iridocorneal angle elements such as Iris (2) or Schwalbe’s line (SL) (3); angle (4) or pupil (5) covered by eyelid; touch by imager’s finger (6); artifactual widening of angle (7) or Invisible pupil (8) by poor illumination. Artifacts seen on the images include ghost cornea (9), SL shadowing (10), iris shadowing under SL (11), irregular cornea curvature (12), vague endothelium/TM transitioning to determine SL but not due to shadowing (13), and duplicated iris (14).
Results :
Out of 5082 eyes of 2541 glaucoma patients/visits there were 208 eyes of 107 patients/visits (4.09%) were reported ‘poor quality’ and images were considered non-gradable due to the various artifacts seen.
Conclusions :
ASOCT provided good quality images in 96% of cases when evaluating the ACA anatomy. Our study is the largest to date to identify the most common sources of errors in techniques and artifacts of imaging from the sizeable cohort of patients with glaucoma. This new found knowledge will serve to improve the training even further of ophthalmic imagers who is instrumental in making ASOCT images reproducible and usable for longitudinal analyses.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.