OCT-A Artifacts in Glaucoma Patients Increase with Disease Severity

Since glaucoma severity can substantially affect image quality and test-retest reliability when obtaining an OCT scan, it is essential to understand the prevalence of artifacts across the full spectrum of glaucoma, including advanced and severe stages. In a recent study conducted at National Taiwan University Hospital, researchers investigated the prevalence and types of artifacts in OCT angiography (OCT-A) among patients with different glaucoma severities. They found that peripapillary scans were more affected by artifacts, with defocus and eye movement increasing as mean deviation (MD) worsened. Defocus was the most common OCT-A artifact. The findings were reported in Ophthalmology Science. These images from the study show a variety of OCT-A artifacts: (A) Eye movement artifact, seen as horizontal and vertical disruptions in the microvasculature that appear as narrow white or stretched lines on the en face angiogram. (B) Blink artifact, a black horizontal line caused by blinking during image acquisition. (C) Z-offset, loss of image data due to B-scans falling outside the capture window. (D) Stretch (red box) and quilt (arrow) artifacts, resulting from imperfect software correction of eye motion. (E) Shadow artifact, in which a Weiss ring obstructs visualization of the underlying microvasculature. (F) Decentration, displacement of the macular center from the center of the image. (G) Defocus artifact, indicated by the arrow, characterized by decreased visibility of the microvasculature. In addition, reduced capillary density corresponding to a retinal nerve fiber layer defect is indicated by the arrowhead. (H) Vessel doubling, duplication of vessels caused by software correction of eye motion. (I–L) Defocus artifacts affected both the en face angiogram and vessel density measurements. In the images with defocus (I–J), the scan quality index was 6 and macular vessel densities were decreased, whereas in the images without defocus (K–L), the scan quality index was 8 and macular vessel densities were higher than in the defocused images. Photo: Hsia Y, et al. Ophthalmol Sci. September 26, 2025. Click image to enlarge. From January to December 2022, 188 patients with open-angle glaucoma were categorized into mild, moderate, advanced and severe groups based on MD values obtained by 24-2 visual field testing.AngioVue OCT-A was performed three times within a single visit to obtain superficial and deep macular vessel density (VD) with 3x3mm macular scans and peripapillary VD with 4.5x4.5mm scans centered on the optic disc. The variability between imaging sessions was assessed by the coefficient of variation (CoV). Different types of image artifacts were identified.The authors found that peripapillary OCT-A scans were more susceptible to artifacts than macular scans, with the proportion of certain artifact types increasing in tandem with glaucoma severity. Defocus was the most common artifact (26%) and increased with worsening MD, contributing to greater CoV of superficial and deep macular VD and reduced macular scan quality index (SQI), which rates image quality on a scale of 1 to 10, based on factors such as signal strength, motion artifacts and focus.They also found that artifacts are highly prevalent in OCT-A imaging, particularly in advanced stages of glaucoma, and significantly impact the reliability of measurements. Specifically, among OCT-A images with acceptable quality (SQI ≥ 7), artifacts were present in one-fourth of patients with mild glaucoma, rising to half of the patients with severe glaucoma. In contrast, for OCT-A images of poor quality, the proportion of artifacts remained consistently high across all stages of glaucoma.The artifacts being more prevalent in peripapillary scans than in macular scans may be attributed to differences in fixation, the researchers explained in their paper. During macular scans, patients focus on a central target, whereas peripapillary scans require fixation on an eccentric target.“For glaucoma patients, the central VF is relatively preserved, while the peripheral VF is often compromised,” the authors wrote. “As a result, fixation on an eccentric target can be more challenging, particularly in more advanced stages of glaucoma.” This aligns with the findings of this study, where eye movement artifacts of peripapillary scans increased with glaucoma severity, as defined by the MD of the VF.“Since eye movement was more likely to occur due to fixation difficulties during disc image acquisition, this artifact negatively impacts the repeatability of peripapillary VD measurements,” the authors wrote in their paper.It should be noted that patient-related factors such as older age, longer axial length, a higher number of glaucoma medications and worse MD were significantly associated with artifact occurrence.These findings underscore the importance of careful attention to correct image acquisition, particularly in patients with advanced glaucoma, as artifacts may still be present even when the SQI appears to indicate acceptable image quality. “Meticulous image acquisition techniques and comprehensive quality assessments are essential to ensure accurate interpretation of OCT-A data,” the authors concluded in their paper. “Given the existing challenges in image quality, further studies are needed to validate the application of OCT-A in clinical decision-making and to explore strategies for improving image reliability.” Click here for the journal source. Hsia Y, Chang H-L, Wang T-H, et al. The artifacts in macular and peripapillary optical coherence tomography angiography in patients with different severities of glaucoma. Ophthalmol Sci. September 26, 2025. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.