Diagnostic Capability of Three-Dimensional Macular Parameters for Glaucoma Using Optical Coherence Tomography Volume Scans

Abstract

PurposeTo compare the diagnostic capability of three-dimensional (3D) macular parameters against traditional two-dimensional (2D) retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography. To determine if manual correction and interpolation of B-scans improve the ability of 3D macular parameters to diagnose glaucoma.MethodsA total of 101 open angle glaucoma patients (29 with early glaucoma) and 57 healthy subjects had peripapillary 2D RNFL thickness and 3D macular volume scans. Four parameters were calculated for six different-sized annuli: total macular thickness (M-thickness), total macular volume (M-volume), ganglion cell complex (GCC) thickness, and GCC volume of the innermost 3 macular layers (retinal nerve fiber layer + ganglion cell layer + inner plexiform layer). All macular parameters were calculated with and without correction and interpolation of frames with artifacts. The areas under the receiver operating characteristic curves (AUROC) were calculated for all the parameters.ResultsThe 3D macular parameter with the best diagnostic performance was GCC-volume-34, with an inner diameter of 3 mm and an outer of 4 mm. The AUROC for RNFL thickness and GCC-volume-34 were statistically similar for all regions (global: RNFL thickness 0.956, GCC-volume-34 0.939, P value = 0.3827), except for the temporal GCC-volume-34, which was significantly better than temporal RNFL thickness (P value = 0.0067). Correction of artifacts did not significantly change the AUROC of macular parameters (P values between 0.8452 and 1.0000).ConclusionsThe diagnostic performance of best macular parameters (GCC-volume-34 and GCC-thickness-34) were similar to or better than 2D RNFL thickness. Manual correction of artifacts with data interpolation is unnecessary in the clinical setting.

<p>Ganglion Cell Complex Analysis in Glaucoma Patients: What Can It Tell Us?</p>

“…Table 1 summarizes spectral-domain (SD) commercially available OCT protocols used to analyze macular ganglion cells. 18,[38][39][40][41][42][43][44] The RTVue-100 software (Optovue, Inc., Fremont, CA) acquires 26,000 A-scans per second with an axial resolution of 5 μm in the tissue. 18,38 The GCC is defined as the sum of RNFL, GCL and IPL thickness measured from the inner limiting membrane to the IPL boundaries ( Figure 1).…”

“…54 The presence of SD-OCT artifacts caused by segmentation or acquisition errors can limit the diagnostic ability of GCC analysis, and the segmentation artifacts were considered the most frequent in both healthy and glaucoma patients. 39 Other factors might influence the interpretation of GCC results; in particular, the epiretinal membrane can cause errors in segmentation, but also retinal disorders and optic neuropathies can alter the GCC thickness. However, these conditions typically do not exhibit specific patterns of GCC damage, but it is important to consider other potential confounding influencing factors when interpreting GCC maps in glaucomatous eyes.…”

Artifact Rates for 2D Retinal Nerve Fiber Layer Thickness Versus 3D Neuroretinal Rim Thickness Using Spectral-Domain Optical Coherence Tomography

“…Three-dimensional scans may be less susceptible to artifacts than 2D scans because they carry a higher density of information (e.g., 193 B-scans in a raster pattern vs. a single circular B-scan). 29 , 31 If one B-scan contains an artifact, neighboring B-scans can provide sufficient information to correct the affected frame or B-scan. In contrast, the accuracy of 2D peripapillary RNFL thickness relies on a single frame, so there are no neighboring scans to correct for any bad data.…”

“… 19 , 30 , 42 Studies of high-density peripapillary RNFL volume scans and high-density macular volume scans have likewise found that average group RNFL volume and average group macular volume values were similar before and after correction of artifacts and subsequent automated interpolation. 21 , 31 On the other hand, 2D peripapillary RNFL thickness and 2D neuroretinal rim measurements generated along a flat reference plane (e.g., cup-to-disc ratio and rim area) on average undergo significant changes after correction of segmentation errors. 17 , 23 , 24 , 40 , 43 The need to manually fix errors or repeat scans in the clinic requires extra time and attention, and parameters derived from 3D volume scans appear to reduce this need.…”

Three-dimensional Neuroretinal Rim Thickness and Visual Fields in Glaucoma: A Broken-stick Model

“…Recently, it has been shown that harnessing the additional structural information from 3D OCT data provides at least the same, or better, diagnostic capabilities as RNFL thickness measurements in 2D, but with fewer artifacts. 14 – 21 In particular, two candidate 3D neuroretinal rim parameters, namely (1) the Bruch’s membrane opening-minimum rim width (BMO-MRW) and (2) the minimum distance band (MDB) thickness, have been identified to better delineate the ONH geometry through OCT-derived features. 14 , 17 , 20 , 22 The BMO-MRW is defined by the minimum distance between the BMO and the inner limiting membrane (cup) surface and is calculated using a relatively low-density radial scan protocol.…”