Intraeye retinal nerve fiber layer and macular thickness asymmetry measurements for the discrimination of primary open-angle glaucoma and normal tension glaucoma

Abstract

PurposeThe aim of this study was to evaluate the diagnostic capability of intraeye retinal nerve fiber layer (RNFL) thickness and macular thickness (MT) asymmetry measurements for the discrimination of normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) using spectral domain optical coherence tomography (SD-OCT).MethodsA total of 90 subjects were enrolled including 30 consecutive healthy subjects, 30 consecutive subjects with POAG, and 30 consecutive subjects with NTG. RNFL thicknesses around the optic disc as well as MT measurements were taken with circular and radial SD-OCT scans. Intraeye retinal and MT asymmetry were calculated as the absolute difference between superior and inferior hemispheres of the eye using posterior pole asymmetry analysis protocol. Analysis of variance was used for comparison and areas under the receiver operating characteristic (AROC) were obtained for different parameters among the three diagnostic groups.ResultsThere was a significant difference in MT asymmetry for all comparison groups (normal-NTG, p < 0.05; normal-POAG, p < 0.001; and NTG-POAG, p < 0.001). Intraeye retinal nerve fiber thickness asymmetry measurements were not different between the groups (normal-NTG, p < 0.187; normal-POAG, p < 0.056; and NTG-POAG, p < 0.837). The area under ROC curves exceeded 0.800 for all the studied parameters, including the MT asymmetry except for intraeye RNFL thickness asymmetry which had the lowest AROC as well as the least sensitivity for identifying subjects with NTG from normal (AROC = 0.626, sensitivity = 30%); POAG from normal (AROC = 0.644, sensitivity = 37%) and NTG from POAG (AROC = 0.533, sensitivity = 13%).ConclusionThe intraeye MT asymmetry holds significant potential as a distinguishing parameter for NTG and POAG.

Comparison of retinal nerve fiber layer and macular thickness for discriminating primary open‐angle glaucoma and normal‐tension glaucoma using optical coherence tomography

“…Furthermore, although a decrease in RNFL and macular thicknesses has been reported in glaucomatous eyes, there is a paucity of data on the discriminating capability of these parameters between NTG and POAG. We have previously established normative data on RNFL thickness in our population and also highlighted the relation between RNFL thickness and visual field sensitivity along with the significant potential of intraeye macular thickness asymmetry for the discrimination of NTG and POAG . In this study, we aimed to establish the distinction in these parameters between NTG and POAG to provide a new dimension to the diagnosis and management of these entities.…”

“…We have previously established normative data on RNFL thickness in our population and also highlighted the relation between RNFL thickness and visual field sensitivity along with the significant potential of intraeye macular thickness asymmetry for the discrimination of NTG and POAG. 16,21,22 In this study, we aimed to establish the distinction in these parameters between NTG and POAG to provide a new dimension to the diagnosis and management of these entities. This could further contribute to early detection, prior to the observance of functional defects on the subjective tests.…”

Macular imaging with optical coherence tomography in glaucoma

“…30 Utility of vertical macular asymmetry for glaucoma detection has been the subject of a number of studies since then. 7,25,72,76,168,186,191,226,227,344,366,386,414,416,418 However, differences in study design including sample size, type of glaucoma, refractive error, ethnicity, disease stage, layer(s) of interest and method of asymmetry analysis should be considered when comparing the results of these studies. Most current SD-OCT devices are able to measure GCC, GCIPL, mRNFL, and FMT that could be used for hemispheric intra-eye or inter-eye asymmetry comparisons.…”

“…Various methods have been used to estimate vertical asymmetry along the temporal raphe or horizontal midline, including thickness difference, 25,76,168,186,191,227,333,335,344,366,386,416 inferior to superior retinal thickness ratio, 30, 186 and the absolute value of the logarithm of superior/inferior retinal thickness. 168,414 Spectralis SD-OCT (Heidelberg Engineering, Germany) was the first OCT device to incorporate a macular asymmetry analysis within its macular imaging algorithm (PPA) (Figure 6).…”

Ability of Macular Inner Retinal Layer Thickness Asymmetry Evaluated by Optical Coherence Tomography to Detect Preperimetric Glaucoma

“…4,5 In normal eyes, the retinal layers seem to be fairly symmetric in terms of the mean thickness in the central parafoveal region between the upper and lower segments as determined by SD-OCT. 6 Asymmetrical differences in the thickness of the inner retinal layer between the upper and lower segments of the macula in PPG eyes were initially investigated using SD-OCT in 2011. 7 Since then, several studies have revealed that asymmetry in the thickness of the retinal layers tends to offer better diagnostic performance than assessment of other thickness parameters, [8][9][10][11][12][13][14] and asymmetry in the thickness of the ganglion cell layer (GCL)/inner plexiform layer (IPL) tends to offer better diagnostic performance than in the RNFL layer in glaucomatous or PPG eyes. 15 However, the degree of difference between the values of the upper and lower segments of the macular inner retinal layers that defines abnormal conditions in the clinical diagnosis of PPG remains to be determined.…”