Diagnostic ability of inner macular layers to discriminate early glaucomatous eyes using vertical and horizontal B-scan posterior pole protocols

Abstract

PurposeTo evaluate the diagnostic ability of macular ganglion cell (mGCL) and macular retinal nerve fiber (mRNFL) layers, to detect early glaucomatous eyes, using the new segmentation software of Spectralis optical coherence tomography (OCT) device (Heidelberg Engineering).MethodsA total of 83 eyes from 83 subjects were included in this observational, prospective cross-sectional study: 43 healthy controls and 40 early primary open-angle glaucoma (POAG) patients. All participants were examined using the Horizontal and Vertical Posterior Pole protocols, and the peripapillary RNFL (pRNFL) protocol of Spectralis OCT device. The new automated retinal segmentation software was applied to horizontal and vertical macular B-scans to determine mGCL and mRNFL thicknesses in each one of the 9 sectors of the Early Treatment Diagnostic Retinopathy Study circle. Thickness of each layer was compared between groups, and the sectors with better area under the receiver operating characteristic curve (AUC) were identified.ResultsmGCL was significantly thinner in the POAG group, especially in outer and inner temporal sectors (p<0.001); and mRNFL was significantly thinner in the POAG group in the outer inferior and the outer superior sector (p<0.001). Diagnostic accuracy of inner macular layers was good, and in general mGCL was superior to mRNFL. pRNFL obtained the best diagnostic capability (AUC, 0.886). Horizontal and vertical Posterior Pole protocols performed similarly.ConclusionsInner macular layers using either horizontal or vertical B-scans, especially temporal sectors of mGCL, have good diagnostic capability to differentiate early glaucomatous eyes from control eyes; however, pRNFL has the highest diagnostic sensitivity for glaucoma detection.

Modelling normal age-related changes in individual retinal layers using location-specific OCT analysis

“…Note, the preset scan pattern with the highest number of B-scans produces a much lower automatic real time mean function and significantly lower image quality, and hence was not used. The difference in horizontal versus vertical B-scan resolution has been shown not to have a significant impact on thickness outcomes 33 . Scans with significant artefacts or signal strength of lower than 15 dB were excluded.…”

Impact of optical coherence tomography scan direction on the reliability of peripapillary retinal nerve fiber layer measurements

“…Comparing the pRNFL thickness measured with horizontal and vertical scans, the horizontal sectors show better agreement compared to the vertical sectors in both scan setting (1 and 2). Comparison of macular thickness measurements with horizontal and vertical scan directions has been reported previously [ 19 , 27 , 28 ]. To our knowledge, this is the first study that compared the influence of different scan directions on the pRNFL measurements.…”

Macular imaging with optical coherence tomography in glaucoma

“…75,76,344,416 The diagnostic ability of individual or combined layer measurements derived from Spectralis OCT has been explored in recent investigations. The GCL 31,65,90,243,253,295 , GCC, 65,192 and mRNFL 68 thickness were found to be the single best parameter for detection of glaucoma in different studies; however, no consistent difference has been observed between macular outcomes of interest. Inner macular thickness measurements on larger grids 65 or outer sectors 31,68,243,295 have displayed better diagnostic capability for early and preperimetric glaucoma.…”

“…The GCL 31,65,90,243,253,295 , GCC, 65,192 and mRNFL 68 thickness were found to be the single best parameter for detection of glaucoma in different studies; however, no consistent difference has been observed between macular outcomes of interest. Inner macular thickness measurements on larger grids 65 or outer sectors 31,68,243,295 have displayed better diagnostic capability for early and preperimetric glaucoma. Also, temporal 31,295 or temporal and inferior 68,90 macular sectors have generally performed better for this task.…”

“…Inner macular thickness measurements on larger grids 65 or outer sectors 31,68,243,295 have displayed better diagnostic capability for early and preperimetric glaucoma. Also, temporal 31,295 or temporal and inferior 68,90 macular sectors have generally performed better for this task. Segmental macular analysis also showed good diagnostic performance for detection of normal tension glaucoma and congenital glaucoma.…”