Patient Characteristics Associated With Artifacts in Spectralis Optical Coherence Tomography Imaging of the Retinal Nerve Fiber Layer in Glaucoma

Abstract

Purpose To determine patient factors and eye conditions associated with artifacts in Spectralis optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) scans. Design Retrospective cross-sectional study. Methods The prevalence of twelve artifact types were described in this review of 2313 eye scans from 1188 patients who underwent a complete eye exam with Spectralis OCT scanning during the period of September 2009 to July 2013. Generalized estimating equations model was utilized to analyze associations between increased artifact prevalence and 10 patient characteristics, which included age, sex, race, visual acuity, refractive error, astigmatism, cataract status, glaucoma staging, visual field reliability, and glaucoma diagnosis. Results A total of 1070 or 46.3% of the 2313 eye scans had at least one artifact. De-centration error was the most common artifact (27.8%), followed by posterior vitreous detachment artifacts (14.4%). Visual acuity of less than 20/40 (p<0.0001), presence of moderate to severe cataracts (p<0.0001), advanced stage of glaucoma (p<0.0001), and a diagnosis of open angle glaucoma (p=0.0003) were associated with increased prevalence of artifacts. Conclusions Clinicians should first assess scans for artifacts before making therapeutic decisions based on RNFL thickness measurements.

Diagnostic Capability of Peripapillary Three-dimensional Retinal Nerve Fiber Layer Volume for Glaucoma Using Optical Coherence Tomography Volume Scans

“…32,45–48 In the current study of 3D RNFL volume, we also found that algorithm failure in segmenting the posterior border of the RNFL was higher in OAG patients (16.9%) compared to normal patients (12.2%), and this is consistent with a previous report from our group. 32 Accurate RNFL thickness measurements are more difficult to obtain in glaucoma patients, because glaucomatous disease causes thinning of the RNFL and also loss of reflectivity of this layer. When there is a decrease in RNFL reflectivity, it is more challenging for automated OCT algorithms to differentiate the posterior RNFL border from the less reflective underlying structures.…”

“…28–31 Decentration artifacts are known to occur in about 27.8% of RNFL thickness circular scans. 32 In contrast, 3D RNFL volume scans are more robust and not subject to these measurement errors, because our algorithm automatically determines the center of the ONH. 33–36 …”

Enhanced Diagnostic Capability for Glaucoma of 3-Dimensional Versus 2-Dimensional Neuroretinal Rim Parameters Using Spectral Domain Optical Coherence Tomography

“…5,7,9,21 However, the lack of a true anatomical landmark as the focal center for circle scans allows for inaccuracies in RNFL measurements due to de-centration, 19,21 which has been reported in even 27.8% of RNFL scans. 43 It has been reported that for mild to advanced glaucoma, 70% to 94% of RNFL defects are diffuse in nature with some patients exhibiting changes only nearer to the RPE/BM complex. 18 As such, measuring at a fixed distance from the disc can lead to misdiagnosis in certain patients, because there are individual as well as ethnic variations in disc size and because the RNFL is normally thicker closer to the RPE/BM complex.…”

Diagnostic Capability of Peripapillary Retinal Volume Measurements in Glaucoma

“…Errors in RNFL thickness measurements have been reported to range from 18.0 to 46.7%. 30, 33–36 Peripapillary 3D RV measurements may have advantages over the traditional 2D RNFL thickness measurements, because RV measurements have lower rates of artifacts (i.e. 7.4% compared to 42.9% in the current study).…”

“…The definitions of these artifacts were previously described. 30 For 3D RV scans, the types of artifacts we detected include misidentification of the anterior and posterior retinal borders, PVD-associated artifacts, missing parts, incomplete segmentation, cut edge, as well as inversion and mirror artifacts, which were not seen in 2D RNFL scans. The definitions of mirror and inversion artifacts were previously described by Han and Jaffe.…”