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Background/aims: Optical coherence tomography angiography (OCT-A) images are subject to variability, but the extent to which learning impacts OCT-A measurements is unknown. We determined whether there is a learning effect in glaucoma patients and healthy controls imaged with OCT-A., Methods: Ninety-one open-angle glaucoma patients and 54 healthy controls were imaged every 4 months over a period of approximately 1 year in this longitudinal cohort study. We analysed 15°×15° scans, centred on the fovea, in one eye of each participant. Two-dimensional projection images for the superficial, intermediate and deep vascular plexuses were exported and binarised after which perfusion density was calculated. Linear mixed-effects models were used to investigate the association between perfusion density and follow-up time., Results: The mean (SD) age of glaucoma patients and healthy controls was 67.3 (8.1) years and 62.1 (9.0) years, respectively. There was a significant correlation between perfusion density and scan quality in both glaucoma patients (r=0.50 (95% CI 0.42 to 0.58); p<0.05) and healthy controls (r=0.41 (95% CI 0.29 to 0.52); p<0.05). An increase in perfusion density occurred over time and persisted, even after adjustment for scan quality (1.75% per year (95% CI 1.14 to 2.37), p<0.01)., Conclusions: Perfusion density measurements are subject to increasing experience of either the operator or participant, or a combination of both. These findings have implications for the interpretation of longitudinal measurements with OCT-A., Competing Interests: Competing interests: JRV: EadieTech (Consultant); PER: Allergan, Bausch and Lomb (Consultant); LMS: Alcon, Allergan, Basuch and Lomb (Consultant); MTN: Allergan (Consultant and Lecturer), Alcon (Lecturer), Bausch and Lomb (Consultant), Heidelberg Engineering (Equipment Support), Labtican (Consultant), Thea (Consultant); BCC: CenterVue, Heidelberg Engineering, Topcon (Equipment Support), (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To understand the added value of Bruch's membrane opening-minimum rim width (BMO-MRW) measurements to conventional circumpapillary retinal nerve fibre layer (cpRNFL) thickness measurements on optical coherence tomography (OCT) imaging for discriminating between perimetric glaucoma and healthy eyes, evaluated through a qualitative evaluation., Methods: 384 healthy eyes and 188 glaucoma eyes were evaluated, and glaucoma eyes were categorised as perimetric (n=107) based on a history of ≥3 consecutive abnormal 24-2 visual field tests or suspected glaucoma if they did not (n=81). OCT-derived BMO-MRW and cpRNFL reports were qualitatively evaluated by two experienced graders in isolation at first, and then by using both reports combined. The diagnostic performance (sensitivity at 95% specificity, total and partial area under the receiver operating characteristic curve) of detecting perimetric glaucoma with each method were compared., Results: All diagnostic performance measures for detecting perimetric glaucoma eyes were not significantly different when using either the cpRNFL or BMO-MRW reports alone compared with using both reports combined (p≥0.190), nor when comparing the use of each report in isolation (p≥0.500)., Conclusions: Experienced graders exhibited no difference in discriminating between perimetric glaucoma and healthy eyes when using a cpRNFL report alone, the BMO-MRW report alone or the two reports combined. Therefore, either OCT imaging report of the neuroretinal tissue could be used effectively for detecting perimetric glaucoma, but further studies are needed to determine whether there are specific advantages of each method, or the combination of both, when evaluating eyes that have a greater degree of diagnostic uncertainty., Competing Interests: Competing interests: DCH: financial support—Topcon (F, C), Heidelberg Engineering (F, C)., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To determine the frequency with which retinal tissues other than the nerve fibre layer, hereafter referred to as protruded retinal layers (PRL), are a component of optical coherence tomography (OCT) neuroretinal rim measurements., Methods: Ninety healthy (30 White, Black and Japanese, respectively) subjects were included in the study. A radial scan pattern (24 B-scans centred on Bruch's membrane opening [BMO]) was used. For each of the 48 minimum rim width (MRW) measurement points, we determined whether PRL were present, absent or indeterminate. When present, the proportion of PRL within the MRW was quantified., Results: Protruded retinal layers were present in 503 (11.6%), absent in 3805 (88.1%) and indeterminate in 12 (0.3%) measurement points. Overall, 69 (76.6%) subjects had ≥1 points with PRL, with White subjects having the highest frequency and Japanese the lowest (29 [97%] and 18 [60%], respectively; p < 0.01). PRL were present in one-third of points in the temporal sector, but ≤5% in other sectors. When present, the median PRL thickness was 53.0 (interquartile range [IQR]: 33.0 to 78.5) μm, representing 20.6 (IQR: 13.0 to 28.5)% of MRW. Globally, the median PRL thickness comprised 1.3 (IQR: 0.2 to 3.5)% of the MRW; however, in the temporal sector, it exceeded 30% of MRW in some subjects., Conclusions: Protruded retinal layers are a component of MRW measurements in most normal subjects, occurring in almost 12% of all measurement points analysed. There were racial variations in the presence of PRL and a significantly higher frequency of PRL in the temporal sector., (© 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Purpose: To investigate the reproducibility of Bruch's membrane opening minimum rim width (BMO-MRW) and retinal nerve fibre layer thickness (RNFLT) measurements using spectral domain optical coherence tomography (SD-OCT). Additionally, to investigate the reproducibility of BMO area measurements and fovea to BMO centre (FoBMO) angle., Methods: Participants were healthy subjects (n = 30) and patients with glaucoma (n = 26). One eye of each participant was scanned to obtain optic nerve head (24 radial B-scans) and peripapillary (one circular B-scan) images by three independent examiners. Additionally, one examiner imaged each participant three times on the same day. Intra- and interobserver reproducibilities were estimated by within-subject standard deviation (SW) and coefficient of variation (COV). Spearman's rank correlation coefficient was used to test the correlation between the magnitude of the parameter and its standard deviation., Results: The global BMO-MRW COVs (%) in healthy/glaucoma subjects were 0.87/1.34 and 1.28/3.13 for intra- and interobserver analyses, respectively, and the corresponding global RNFLT figures were 1.50/2.10 and 2.04/2.87. Global mean BMO-MRW and RNFLT showed no correlation with their respective standard deviations. The reproducibilities of BMO area and FoBMO angle were excellent and similar between the groups., Conclusion: The reproducibilities of BMO-MRW, BMO area measurements and FoBMO angle were excellent in both healthy subjects and patients with glaucoma. Bruch's membrane opening minimum rim width (BMO-MRW) reproducibility is comparable to that of RNFLT measurements., (© 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Purpose: To compare the visibility of deep optic nerve head (ONH) structures and the visible area of the anterior surface of the lamina cribrosa (ASLC) with spectral-domain optical coherence tomography (SD-OCT) and swept-source OCT (SS-OCT)., Materials and Methods: In total, 33 glaucoma patients were imaged with SD-OCT (Spectralis, 24 radial B-scans centered on the ONH) and SS-OCT (Atlantis, 12 radial and a horizontal and vertical raster scan pattern containing 5 lines each, centered on the ONH). One of the SS-OCT horizontal and vertical scans that was best matching with the horizontal and vertical scan lines with those of SD-OCT was selected. All B-scans were then exported and deidentified. An independent observer determined whether the posterior choroid, border tissue, anterior scleral canal opening, and LC insertion into the sclera were detectable in the matched scan lines. Bruch membrane opening (BMO) and ASLC were segmented manually in radial scans. The segmented points were combined into a single plane and a linear interpolation was used to define BMO and ASLC areas., Results: The posterior choroid, border tissue, and anterior scleral canal opening were detectable in most patients (94% to 100%, 88% to 100%, and 76% to 100%, respectively) and were not different between SD-OCT and SS-OCT. The LC insertion detection rate was nonstatistically higher for SS-OCT compared with SD-OCT (58% to 85% vs. 42% to 73%; P>0.10). The mean (SD) ASLC visible area (percentage of the respective BMO area) was 124 (30%) with SD-OCT and 135 (32%) with SS-OCT (P<0.01)., Conclusion: SD-OCT and SS-OCT had comparable detection rates of deep ONH structures; however, a larger area of ASLC was visible with SS-OCT.

Purpose: To determine whether beta and gamma peripapillary atrophy (PPA) areas measured with optical coherence tomography (OCT) enhances glaucoma diagnosis in myopic subjects., Methods: We included 55 myopic glaucoma patients and 74 myopic nonglaucomatous controls. Beta-PPA comprised the area external to the clinical disc margin, with absence of retinal pigment epithelium and presence of Bruch's membrane. Gamma-PPA comprised the area external to the disc margin, with absence of both RPE and Bruch's membrane. OCT scans colocalized to fundus photographs were used to measure PPA, choroidal thickness, border tissue of Elschnig configuration, optic disc area, and optic disc ovality., Results: Beta-PPA area was larger in glaucoma patients compared with controls (median [interquartile range], 1.0 [0.66-1.53] mm2 and 0.74 [0.50-1.38] mm2, respectively), whereas gamma-PPA was smaller in glaucoma patients compared with controls (0.28 [0.14-0.50] mm2 and 0.42 [0.17-0.74] mm2, respectively). However, the distributions of both beta- and gamma-PPA in the two groups overlapped widely. The areas under the receiver operating characteristic curve of beta- and gamma-PPA areas were 0.60 and 0.59, respectively. Larger beta-PPA area was associated with larger disc area, thinner choroidal thickness, longer axial length, less oblique border tissue configuration, older age, and greater disc ovality. Larger gamma-PPA area was associated with greater disc ovality, more oblique border tissue configuration, and longer axial length., Conclusions: Subclassifying PPA with OCT into beta and gamma zones reveals association with different covariates, but does not enhance the diagnostic performance for glaucoma in a population of predominantly Caucasians myopic subjects.

Purpose: To compare the diagnostic accuracy of conventional sector-based analysis with a method devised to detect the smallest localized neuroretinal rim and retinal nerve fiber layer thickness (RNFLT) damage., Methods: One eye of 151 glaucoma patients and 83 healthy controls (median age and MD, 71.7 and 66.7 years, and -3.6 and -0.3 dB, respectively) was imaged with spectral-domain optical coherence tomography (OCT). Bruch's membrane opening-minimum rim width (BMO-MRW) and RNFLT were determined at 1° intervals and also averaged for each sector. A classification of glaucoma was made with sectoral analysis when the sectoral value was below the 1%, 5%, or 10% normative limit (from an independent normative dataset); and with total analysis when a given number of measurements was below the 1%, 5%, or 10% normative limit., Results: With the 1% normative limit, BMO-MRW sectoral analysis yielded sensitivity of 87% and specificity of 92%; while at the same specificity (92%), total analysis yielded sensitivity of 88%. With RNFLT, sectoral analysis yielded sensitivity of 85% and specificity of 95%; while at the same specificity (95%), total analysis yielded sensitivity of 83%. The results for the 5% and 10% normative limits yielded lower specificity but higher sensitivity. In the whole glaucoma population, none of the sensitivity values of the sectoral and total analysis at the same specificities were statistically different., Conclusions: The diagnostic accuracy of sectoral analysis was equivalent to total analysis. These results indicate that BMO-MRW and RNFLT defects were wide and deep enough for detection by conventional sectoral analysis.