Retinal Nerve Fiber Layer Scans Research Articles

Biological and Methodological Variability in Retinal Nerve Fiber Layer OCT: The Framingham Heart Study

ObjectiveTo explore participant-level biological attributes and scan-level methodological attributes associated with retinal nerve fiber layer (RNFL) thickness variability in a population-based sample of elderly United States adults. DesignCross-sectional analysis using data from the Framingham Heart Study. Participants1,347 eyes from 825 participants with at least one optical coherence tomography (OCT) scan and axial length data were included. MethodsThree or more successive RNFL scans of each eye of each participant were obtained in a single session. Multivariable linear mixed models were employed to explore the associations between average RNFL thickness with participant-level biological attributes (age, gender, race, ethnicity, and axial length) and scan-level attributes (signal strength [SS]) as independent variables in the whole population as well as a sub-sample of adults with no self-reported history of glaucoma. Similar analyses were designed to assess methodological variability with average within-eye standard deviation (SD) for repeated scans as the dependent variable. Main Outcomes1) Biological variability: average RNFL thickness, 2) Methodological variability: average within- participant SD across repeated scans. ResultsAge (β= −0.19 microns/year, [95% CI: −0.29, −0.09]), female gender (β= +1.48 microns vs. male, [95% CI: 0.09,2.86]), axial length (β= −1.24 microns/mm of greater length, [95% CI: −1.80, −0.67]), and SS (β= +1.62 microns/1 unit greater SS, [95% CI: 1.16,2.09]) were significantly associated with RNFL thickness, while race and ethnicity were not (p>0.05). In analyses designed to assess methodological variability, higher RNFL thickness (β= +0.02 per micron increase, [95% CI: 0.01,0.03]), and lower SS (β= +0.19 per 1 unit lower SS, [95% CI: 0.10,0.27]) were significantly associated with greater RNFL variability. In adults with no self-reported history of glaucoma (n of eyes = 1165, n of participants = 712), female gender was not associated with RNFL, while African-American race was associated with thicker RNFL (β= +4.65 microns vs. Whites, [95% CI: 1.28,8.03]). ConclusionsRNFL thickness is lower with older age, male gender, greater axial length, lower signal strength, and Whites (as compared to African-Americans) without self-reported glaucoma. Measurement variability (SD) is higher with greater RNFL thickness and lower SS. Understanding these biological and methodological variations is important to aid in OCT interpretation.

Visual Characteristics of Adults with Long-Standing History of Dietary Exposure to Mercury in Grassy Narrows First Nation, Canada.

Since the 1960s, Grassy Narrows First Nation (Ontario, Canada) has been exposed to methyl mercury (Hg) through fish consumption, resulting from industrial pollution of their territorial waters. This cross-sectional study describes the visual characteristics of adults with documented Hg exposure between 1970 and 1997. Oculo-visual examinations of 80 community members included visual acuity, automated visual fields, optical coherence tomography [OCT], color vision and contrast sensitivity. Median age was 57 years (IQR 51-63) and 55% of participants were women. Median visual acuity was 0.1 logMAR (Snellen 6/6.4; IQR 0-0.2). A total of 26% of participants presented a Visual Field Index inferior to 62%, and qualitative losses assessment showed concentric constriction (18%), end-stage concentric loss (18%), and complex defects (24%). On OCT, retinal nerve fiber layer scans showed 74% of participants within normal/green range. For color testing with the Hardy, Rand, and Rittler test, 40% presented at least one type of color defect, and with the Lanthony D-15 test, median color confusion index was 1.59 (IQR 1.33-1.96). Contrast sensitivity showed moderate loss for 83% of participants. These findings demonstrate important loss of visual field, color vision, and contrast sensitivity in older adults in a context of long-term exposure to Hg in Grassy Narrows First Nation.

Evaluation of Retinal Layer Thicknesses in Patients with Keratoconus Using Retinal Layer Segmentation Analysis.

To conduct an evaluation of the effects of irregular astigmatism on the retinal nerve fiber layer (RNFL) and the retinal layers observed using spectral-domain optical coherence tomography (SD-OCT) in patients who had keratoconus (KC). A total of 255 eyes from 255 individuals, comprising 72 eyes of KC patients, 70 eyes of patients with astigmia, and 113 eyes of healthy controls were included in the analysis. RNFL scan maps (comprising global, temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal maps) and macular thickness (MT) maps of a standard from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid were assessed. The measurements were segmented automatically using Spectralis software, and included the RNFL, inner and outer plexiform layers (IPL, OPL), inner and outer nuclear layers (INL, ONL), ganglion cell layer, retinal pigment epithelium (RPE) in the central 6-mm ETDRS subfield. The RNFL thickness in the KC group was lower when compared with the other two groups; however, statistically significant differences were noted in the global, temporal, superotemporal, and inferotemporal sectors (p < 0.05 for all). All of the central MT parameters showed significant variation among the groups, while a statistically significant decrease was noted in the KC group, except in the inferior outer sector (p = 0.741). In the segmentation analysis, the KC group had the significantly lowest IPL, ONL, RPE, and outer retinal layer (ORL) thickness among the groups (p < 0.05 for each). The astigmatic group was similar to the control group with regard to these parameters (p > 0.05 for each). The eyes in the KC group appeared to have a thinner RNFL and MT when compared to those in the astigmatic and control groups. The ORLs, especially the ONL and RPE, were the most affected component of the macula in the KC group.

Spectral domain optical coherence tomography for detecting glaucoma

Purpose: To evaluate the diagnostic ability of macular thickness parameters and peripapillary retinal nerve fiber layer (RNFL) thickness parameters for detecting glaucoma using spectral domain optical coherence tomography (SD–OCT).&#x0D; Methods: 37 eyes of 20 glaucoma patients and 30 eyes of 16 healthy subjects included in this study underwent macular and peripapillary RNFL scans with SD–OCT using standard scanning parameters. The ”Macular Cube 512x128” scan protocol was used to measure the macular thickness. The ”Optic Disc Cube 200x200” scan protocol was used for assessing the peripapillary region. The discrimination power of all parameters for detecting glaucoma was determined by the Area under Receiver Operating Characteristics (AROC) curve and sensitivity at fixed specificity, followed by a comparison of the best macular thickness and peripapillary RNFL thickness parameters.&#x0D; Results: Significant differences between glaucoma patients and healthy subjects were found in all peripapillary RNFL thickness parameters and all macular thickness parameters, except in the fovea (p=0.322). The largest AROC with sensitivity at &gt;90% specificity among the peripapillary RNFL thickness parameters was found for the average peripapillary RNFL thickness (AROC 0.95, sensitivity 76%). The largest AROC with sensitivity at &gt;90% specificity among the macular parameters was found for the inferior inner macular thickness (AROC 0.90, sensitivity 78%). There was no statistically significant difference between the AROCs of these two parameters (p=0.208).&#x0D; Conclusion: To discriminate glaucoma patients from healthy subjects using SD–OCT, macular thickness parameters had high diagnostic ability which was comparable to that of the peripapillary RNFL thickness parameters.

Optical coherence tomography-signal strength index following trifocal and monofocal intraocular lens implantation

PurposeTo evaluate the influence of trifocal and monofocal intraocular lens implantation on the optical coherence tomography-signal strength index values obtained during macular and peripapillary scanning. MethodStudy group included 60 eyes of 60 patients with intraocular lens (Acriva BB UD 613 monofocal in 30 eyes and Acriva Trinova UD trifocal in 30 eyes) implantation after uneventful phacoemulsification. Thirty eyes of 30 healthy subjects without any intraocular surgery were selected as the control group. Eyes with best corrected visual acuity less than 20/20 due to any media opacity, high refractive errors excluded. Macular and retinal nerve fiber layer scans were generated by optical coherence tomography after pupillary dilation. Intergroup comparisons of signal strength index values of the macular and peripapillary scans were performed between eyes implanted with two different intraocular lenses and control group. ResultsThe mean signal strength index of the peripapillary and macular scans obtained in the eyes implanted with both monofocal and trifocal intraocular lenses were statistically less than the control group (p < 0.05, for all). SSI's of macular and peripapillary scans recorded from the eyes implanted with either monofocal or trifocal intraocular lenses were not statistically different from each other (p = 0.957 and p = 0.877, respectively). ConclusionIn the present study despite different intraocular lenses properties, the image quality values were not found to be lower in eyes with trifocal sinusoidal intraocular lenses implantation compared to monofocal intraocular lenses during macular and peripapillary optical coherence tomography scans.

Analysis of imaging biomarkers and retinal nerve fiber layer thickness in RPGR-associated retinitis pigmentosa

PurposeTo investigate multimodal retinal imaging characteristics including the retinal nerve fiber layer (RNFL) thickness in patients with RPGR-associated retinitis pigmentosa (RP).MethodsThis cross-sectional case–control study included 17 consecutive patients (median age, 21 years) with RPGR-associated RP who underwent retinal imaging including optical coherence tomography (OCT), short-wavelength fundus autofluorescence (AF) imaging, and RNFL scans centered on the optic disc. RNFL thickness was manually segmented and compared to clinical and imaging parameters including the transfoveal ellipsoid zone (EZ) width, the horizontal diameter of the macular hyperautofluorescent ring. RNFL thickness was compared to 17 age- and sex-matched controls.ResultsIn patients with RPGR-associated RP, the EZ width (R2 = 0.65), the central hyperautofluorescent ring on AF images (R2 = 0.72), and visual acuity (R2 = 0.68) were negatively correlated with age. In comparison to controls, a significantly (p < 0.0001) increased global RNFL thickness was identified in RPGR-associated RP, which was, however, less pronounced in progressed disease as indicated by the EZ width or the diameter of the central hyperautofluorescent ring.ConclusionsThis study describes retinal characteristics in patients with RPGR-associated RP including a pronounced peripapillary RNFL thickness compared to healthy controls. These results contribute to the knowledge about imaging biomarkers in RP, which might be of interest for therapeutic approaches such as gene replacement therapies.

Evaluation of practices of macular ganglion cell complex scan in early detection of glaucoma.

The purpose of this survey was to evaluate the level of awareness and practices regarding macular ganglion cell complex (GCC) scans for early detection of glaucoma. The study design was descriptive cross-sectional and the sampling technique was non-probability convenient method. Data was collected through an online survey, from 100 practicing ophthalmologists and optometrists of Pakistan in two weeks, from January 20 to February 03 2019. Data were analysed using Microsoft Excel 2016. From the results it is strongly evident that significant number of respondents recorded the retinal nerve fibre layer (RNFL) to be the first layer affected as glaucoma progresses, which depicts lack of knowledge among eye care practitioners. Furthermore, both the groups (ophthalmologists and optometrists), used macular GCC scan the least as compared to the RNFL (optic nerve head) scan and visual field tests for early diagnosis of glaucoma. It demonstrated lack of knowledge and practices of macular GCC scan for glaucoma among eye care practitioners.

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

PurposeTo compare the rates of clinically significant artifacts for two-dimensional peripapillary retinal nerve fiber layer (RNFL) thickness versus three-dimensional (3D) neuroretinal rim thickness using spectral-domain optical coherence tomography (SD-OCT).MethodsOnly one eye per patient was used for analysis of 120 glaucoma patients and 114 normal patients. For RNFL scans and optic nerve scans, 15 artifact types were calculated per B-scan and per eye. Neuroretinal rim tissue was quantified by the minimum distance band (MDB). Global MDB neuroretinal rim thicknesses were calculated before and after manual deletion of B-scans with artifacts and subsequent automated interpolation. A clinically significant artifact was defined as one requiring manual correction or repeat scanning.ResultsAmong glaucomatous eyes, artifact rates per B-scan were significantly more common in RNFL scans (61.7%, 74 of 120) compared to B-scans in neuroretinal rim volume scans (20.9%, 1423 of 6820) (95% confidence interval [CI], 31.6–50.0; P < 0.0001). For clinically significant artifact rates per eye, optic nerve scans had significantly fewer artifacts (15.8% of glaucomatous eyes, 13.2% of normal eyes) compared to RNFL scans (61.7% of glaucomatous eyes, 25.4% of normal eyes) (glaucoma group: 95% CI, 34.1–57.5, P < 0.0001; normal group: 95% CI, 1.3–23.3, P = 0.03).ConclusionsCompared to the most commonly used RNFL thickness scans, optic nerve volume scans less frequently require manual correction or repeat scanning to obtain accurate measurements.Translational RelevanceThis paper illustrates the potential for 3D OCT algorithms to improve in vivo imaging in glaucoma.

Impact of Artifacts From Optical Coherence Tomography Retinal Nerve Fiber Layer and Macula Scans on Detection of Glaucoma Progression

To determine the prevalence of artifacts on segmented spectral-domain optical coherence tomography (SDOCT) images and assess their impact on the interpretation of glaucomatous progression in the retinal nerve fiber layer (RNFL) profile and macular thickness map. Retrospective reliability analysis. Retrospective review of glaucoma and glaucoma suspect eyes imaged with SDOCT during a 1-month period. All cases had at least 4 sets of RNFL and macular images at 6-month intervals. SDOCT raw B-scans were examined to determine true progression and whether artifacts impacted the original interpretation of progression based on auto-segmented change maps. The co-prevalence of artifacts in the RNFL and macula was assessed, as well as the association of clinical factors with the likelihood of artifacts. A total of 190 eyes with 760 sets of OCT RNFL and macular scans were included. Fifty percent (96/190) of eyes had artifacts, either in the circumpapillary RNFL (83/190; 43.68%) or the macula (57/190; 30.0%). Epiretinal membrane and vitreomacular traction were the most common artifacts. True progression was present on 39.5% (75/190) of scans overall. Among scans with artifacts, 23.9% (23/96) of artifacts masked true progression (ie, false-negative), 36.5% (35/96) led to an interpretation of false progression (ie, false-positive), and 39.6% (38/96) had no effect on the interpretation of progression. The presence of true progression on the RNFL scan was significantly associated with the presence of true progression on the macular scan (P < .001). Similarly, the presence of artifacts on the RNFL scan was significantly associated with artifacts on the macular scan (P < .001). In multivariable analysis, severe glaucoma, hypertension, and age were significantly associated with the presence of artifacts on RNFL (P< .05). Artifacts are highly prevalent on both circumpapillary RNFL and macular scans on SDOCT images acquired in a glaucoma clinic. Artifacts can lead to false-positive and false-negative interpretation of progression when using only the auto-segmentation change maps. Thus, careful examination of the raw B-scan images of both the RNFL and macula is critical to identify artifacts and true glaucoma progression.

Comparison between time-domain and spectral-domain OCT in the detection of retinal nerve fiber layer defects in glaucoma patients

AIM: To compare, using the instruments’ built-in normative databases, the sensitivities of time-domain optical coherence tomography (Stratus OCT) and spectral-domain OCT (Spectralis OCT) in the detection of retinal nerve fiber layer (RNFL) defects in patients with glaucoma. METHODS: Fifty-two eyes of 35 patients with open angle glaucoma were included. A total of 69 hemiretinas with photographically identified RFNL defects were analyzed using the fast RNFL scan of Stratus OCT and the circle scan in Spectralis OCT. The OCT parameters were evaluated at 5% and 1% abnormality levels using the instruments’ built-in normative databases. The diagnostic sensitivity of each parameter was compared between the two devices. RESULTS: The Spectralis OCT detected RNFL defects within each quadrant more frequently than the Stratus OCT at both the 5% (79.7% vs 63.8%, P=0.01) and 1% (56.5% vs 40.6%, P=0.01) abnormality levels. At the 1% abnormality level, the sensitivity was significantly higher in the standard sector of Spectralis OCT than in the clock-hour sector of the Stratus OCT (68.1% vs 39.1%, P&lt;0.01).

The Trajectory of Glaucoma Progression in 2-Dimensional Structural–Functional Space

To present a method that allows visualization of functional and structural change in 2-dimensional space. Retrospective, longitudinal, observational study. Patients from the Stein Eye Institute, UCLA from 1993 through2017. Patients were arranged into 2 cohorts. Cohort 1 was used to create a structural score for the horizontal axis of the structural-functional (S-F) 2-dimensional space. The visual field (VF) index was used for the vertical axis as the functional score. Cohort 2 was used to apply those scores for analysis of S-F progression with a combined vector. The first cohort included eyes with mild glaucoma (abnormal glaucoma hemifield test results, pattern standard deviation <0.05 on 2 examinations, or mean deviation [MD] >-5 dB) and normal control participants. The second cohort included all stages of open-angle glaucoma with ≥5 OCT retinal nerve fiber layer scans, ≥5 reliable visual field (VF) results, and follow-up of ≥4 years. Vectors were created for each eye to represent the trajectory of glaucoma progression over time. Each vector was defined by structural (x-axis) and functional (y-axis) components. The structural component was calculated with a linear model of Heidelberg Retina Tomograph (Heidelberg Engineering, Heidelberg, Germany) scores over time. The functional component was calculated with a linear model of VF measurements over time. The resultant vector and its confidence interval were plotted in 2-dimensional S-F space. Eyes were divided into severity stages based on baseline MD. A mean vector was calculated for each severity stage. We obtained 290 vectors from 290 eyes of 196 patients. The mean ± standard deviation follow-up period was 14.6±3.1 years. Average age was 58.6±8.8 years. Preperimetric, mild, moderate, and severe categories included 41, 89, 97, and 63 eyes, respectively. Mean baseline MDs were 0.8 dB, -0.95 dB, -3.57 dB, and -11.51 dB, respectively, and mean vector slopes for each severity categories were 0.79, 0.95, 1.95, and 2.08, respectively. Cook's distance removed 131 (7.1%) and 137 (7.4%) outliers from the structure and function regressions, respectively. We report a method to visualize the trajectory of a patient's glaucoma progression in a 2-dimensional S-F space. The slope of the trajectory of glaucoma progression is a function of the severity of the disease.

Rates of Glaucomatous Structural and Functional Change From a Large Clinical Population: The Duke Glaucoma Registry Study

To investigate rates of structural and functional change in a large clinical population of glaucoma and glaucoma suspect patients. Retrospective cohort. Twenty-nine thousand five hundred forty-eight spectral-domain optical coherence tomography (OCT) and 19,812 standard automated perimetry (SAP) tests from 6138 eyes of 3669 patients with ≥6months of follow-up, 2 good quality spectral-domain OCT peripapillary retinal nerve fiber layer scans, and 2 reliable SAP tests were included. Data were extracted from the Duke Glaucoma Registry, a large database of electronic health records of patients from the Duke Eye Center and satellite clinics. Rates of change for the 2 metrics were obtained using linear mixed models, categorized according to pre-established cutoffs, and analyzed according to the severity of the disease. Average rates of change were-0.73 ± 0.80μm per year for global retinal nerve fiber layer thickness and-0.09 ± 0.36 dB per year for SAP mean deviation. More than one quarter (26.6%) of eyes were classified as having at least a moderate rate of change by spectral-domain OCT vs 9.1% by SAP (P < .001). In eyes with severe disease, 31.6% were classified as progressing at moderate or faster rates by SAP vs 26.5% by spectral-domain OCT (P= .055). Most eyes classified as fast by spectral-domain OCT were classified as slow by SAP and vice versa. Although most patients under routine care had slow rates of progression, a substantial proportion had rates that could potentially result in major losses if sustained over time. Both structural and functional tests should be used to monitor glaucoma, and spectral-domain OCT still has a relevant role in detecting fast progressors in advanced disease.

Retinal neurodegeneration in patients with end-stage renal disease assessed by spectral-domain optical coherence tomography

Spectral-domain optical coherence tomography (SD-OCT) represents a reliable tool for retinal layer volume and thickness measurement. The aim of this study was to evaluate retinal changes indicating neurodegenerative processes in patients with end-stage renal disease (ESRD) compared to healthy controls. This was a cross-sectional, single-center study comprising 32 ESRD patients and 38 controls. Sectoral retinal nerve fiber layer (RNFL) thickness and retinal layer volumes were obtained by SD-OCT. Age- and gender-adjusted retinal layer volumes such as total retinal volume (p = 0.037), ganglion cell layer volume (GCL, p = 0.003), ganglion cell layer – inner plexiform layer volume (GCL-IPL, p = 0.005) and inner retinal layer volume (IRL, p = 0.042) of the right eye were lower in ESRD patients. Inner plexiform layer volume of both eyes (IPL, right eye: p = 0.017; left eye: 0.044) was reduced, as was RNFL thickness in the temporal superior sector (right eye: p = 0.016). A subgroup analysis excluding patients with diabetes revealed that GCL (p = 0.014) and GCL-IPL volume of the right eye (p = 0.024) and temporal superior sector of the RNFL scan (p = 0.021) in ESRD patients were still significantly thinner. We observed a decrease in several retinal layer volumes and temporal RNFL thickness indicative of retinal neurodegenerative processes in patients with ESRD.

Artifact Rates for 2D Retinal Nerve Fiber Layer Thickness Versus 3D Retinal Nerve Fiber Layer Volume.

PurposeTo compare artifact rates in two-dimensional (2D) versus three-dimensional (3D) retinal nerve fiber layer (RNFL) scans using Spectralis optical coherence tomography (OCT)MethodsThirteen artifact types in 2D and 3D RNFL scans were identified in 106 glaucomatous eyes and 95 normal eyes. Artifact rates were calculated per B-scan and per eye. In 3D volume scans, artifacts were counted only for the 97 B-scans used to calculate RNFL parameters for the 2.5–3.5-mm annulus. 3D RNFL measurements were calculated twice, once before and again after deletion of B-scans with artifacts and subsequent automated interpolation.ResultsFor 2D scans, artifacts were present in 58.5% of B-scans (62 of 106) in glaucomatous eyes. For 3D scans, a mean of 35.4% of B-scans (34.3 of 97 B-scans per volume scan) contained an artifact in 106 glaucomatous eyes. For 3D data of glaucoma patients, mean global RNFL thickness values were similar before and after interpolation (77.0 ± 11.6 µm vs. 75.1 ± 11.2 µm, respectively; P = 0.23). Fewer clinically significant artifacts were noted in 3D RNFL scans, where only 7.5% of glaucomatous eyes (8 of 106) and 0% of normal eyes (0 of 95) had artifacts, compared to 2D RNFL scans, where 58.5% of glaucomatous eyes (62 of 106) and 14.7% of normal eyes (14 of 95) had artifacts.ConclusionsCompared to 2D RNFL scans, 3D RNFL volume scans less often require manual correction to obtain accurate measurements.Translational Relevance3D RNFL volume scans have fewer clinically significant artifacts compared to 2D RNFL thickness scans.

Evaluation of Peripapillary Choroidal Microvasculature to Detect Glaucomatous Damage in Eyes With High Myopia.

Parapapillary choroidal microvasculature dropout (MvD), as observed by optical coherence tomography (OCT) angiography, was useful to detect glaucomatous damage in highly myopic eyes with unreliable OCT results due to segmentation errors. The purpose of this study was to evaluate the usefulness of optical coherence tomography angiography (OCTA) imaging of the peripapillary choroidal microvasculature in detecting glaucomatous damage in highly myopic eyes, in cases where evaluating the thickness of the retinal nerve fiber layer (RNFL) is unreliable due to OCT segmentation errors. Forty-five highly myopic eyes with primary open-angle glaucoma (POAG) with an axial length >26.5 mm, and 15 age-matched and axial length-matched 15 control eyes were included in this cross-sectional observational study. All participants had a segmentation error in OCT circumpapillary RNFL scanning. The peripapillary choroidal microvasculature was evaluated on en-face images obtained using swept-source OCTA. MvD was defined as a focal sectoral capillary dropout with no visible microvascular network identified in the choroidal layer. The topographic correlation between the MvD and a hemifield visual field (VF) defect was assessed using κ statistics. The MvD size was assessed by measuring both its area and circumferential extent. Choroidal MvD was observed in 44 of the 45 (97.8%) POAG eyes with high myopia, while none of the control eyes showed a choroidal MvD. There was an excellent topographic relationship between the choroidal MvD and the hemifield VF defect (κ=0.863, P<0.001). The area (R=0.2619, P=0.0006) and circumferential extent (R=0.3088, P=0.0002) of the MvD have significantly associated with the VF mean deviation. Choroidal MvDs were observed in most of the highly myopic POAG eyes and were topographically correlated with the location of glaucomatous VF defects despite unreliable OCT RNFL thickness measurements. Using OCTA to investigate the choroidal microvasculature may facilitate diagnoses of glaucoma in highly myopic eyes.

New Circumpapillary Retinal Nerve Fiber Layer Thickness and Bruch's Membrane Opening-Minimum Rim Width Assessment in Nonglaucomatous Eyes with Large Discs.

Purpose To compare the new spectral-domain optical coherence tomography (SD-OCT) algorithm for measuring circumpapillary retinal nerve fiber layer (RNFL) thickness centered on Bruch's membrane opening (BMO), RNFLBMO1, with the conventional circumpapillary RNFL thickness measurement centered on the optic disc (RNFLDİ), and assess the BMO-minimum rim width (BMO-MRW) in nonglaucomatous eyes with large discs. Methods This prospective, cross-sectional, observational study included a total of 91 eyes of 91 patients having nonglaucomatous eyes with large discs (Group 1) and 50 eyes of 50 healthy subjects (Group 2). The optic nerve head (ONH) parameters obtained by confocal scanning laser ophthalmoscopy (CSLO), peripapillary RNFL thickness, BMO area, and BMO-MRW were imaged with SD-OCT. Results The mean disc size was 3.06 ± 0.42 mm2 (range, 2.61–4.68) in Group 1 and 1.95 ± 0.23 mm2 (range, 1.6–2.43) in Group 2 (p=0.0001). The mean BMO area was 2.9 ± 0.58 mm2 (range, 1.26–4.62) in Group 1 and 2.05 ± 0.31 mm2 (range, 1.51–2.82) in Group 2 (p=0.0001). The difference between RNFLDİ and RNFLBMO1 measurements in Group 1 was stronger than in Group 2 because it was significant in all sectors in large discs. The mean global BMO-MRW thickness was significantly thinner in large discs; it was 252.95 ± 42.16 µ (range, 170–420) in Group 1 and 326.06 ± 73.39 µ (range, 210–440) in Group 2 (p=0.0001). There was a positive correlation between BMO-MRW thickness measurements and RNFL thickness parameters, both with RNFLDİ and RNFLBMO1, in global and all optic nerve sectors except temporal quadrants with r = 0.257–0.431 (p ≤ 0.001–0.01) in Group 1. But in control group, Group 2, there was a weak correlation or no correlation between BMO-MRW thickness measurements and RNFL thickness parameters with r = −0.256–0.328 (p=0.797–0.02). Conclusion The new circumpapillary RNFL scanning algorithm centered on BMO is better to assess the RNFL thickness and BMO-MRW in large discs for the early diagnosis of glaucoma.

Spectralis OCT1 versus OCT2: Time Efficiency and Image Quality of Retinal Nerve Fiber Layer Thickness and Bruch's Membrane Opening Analysis for Glaucoma Patients.

ABSTRACTPurposeTo compare two generations of Heidelberg SPECTRALIS optical coherence tomography (OCT) technologies (SPECTRALIS OCT1 and OCT2) with regard to time efficiency and image quality of retinal nerve fiber layer (RNFL) thickness and Bruch's membrane opening (BMO) analysis in individuals with glaucoma.Materials and methodsIn this single center, prospective cohort study, 35 consecutive glaucoma patients (70 eyes) were included. RNFL thickness and BMO-MRW analysis was performed in all patients using the Heidelberg SPECTRALIS OCT1 and the Heidelberg SPECTRALIS OCT2 module. Each patient was imaged three times both with the SPECTRALIS-OCT1 and the SPECTRALIS-OCT2 device. All scans were assessed for further analyzability. Acquisition duration, signal-to-noise ratio (SNR), and the displacement between the initially localized and the redetermined BMO center were extracted from the measurement protocols and statistically compared.ResultsMean (cumulative) scan acquisition duration was significantly higher with OCT1 compared with OCT2 (54.80 ± 18.61 seconds vs 20.40 ± 6.61 seconds; p < 0.01). Patient-related comparison showed a lower scan duration with the OCT2 device in all 35 patients. Mean SNR of the OCT1 images was 29.9 dB and 32.3 dB for the OCT2 images. The difference of −2.4 (95% CI: −3.1 to 2) was highly significant (p < 0.001). Mean displacement of the OCT1 images was 42.9 μm and 40.2 μm for the OCT2 images (95% CI: −4.710; p = 0.479).ConclusionWith SPECTRALIS OCT2, acquisition time of BMO and RNFL scans is less than half of the acquisition time of SPECTRALIS OCT1. Image quality of OCT2 module is at least equivalent to the image quality of OCT1.How to cite this articleBosche F, Andresen J, et al. Spectralis OCT1 versus OCT2: Time Efficiency and Image Quality of Retinal Nerve Fiber Layer Thickness and Bruch's Membrane Opening Analysis for Glaucoma Patients. J Curr Glaucoma Pract 2019;13(1):16–20.

Effects of Circumpapillary Retinal Nerve Fiber Layer Segmentation Error Correction on Glaucoma Diagnosis in Myopic Eyes

In a myopic population, we investigated the occurrence of circumpapillary retinal nerve fiber layer (RNFL) segmentation errors that required manual correction in optical coherence tomography (OCT) and its effect on glaucoma diagnostic capability of OCT. Myopic subjects (spherical equivalent refractive error <-3 D) with and without primary open-angle glaucoma were recruited. Three circumpapillary RNFL scans with diameters of 3.45, 4.50, and 6.00 mm were obtained using spectral-domain OCT. RNFL segmentation errors were manually corrected. Receiver operating characteristic curves of retinal nerve fiber layer thickness (RNFLT) were obtained and area under the curves were calculated before and after manual correction. In total, 90 myopic eyes with glaucoma (90 patients; visual field mean deviation, -9.5±7.1 dB) and 58 myopic eyes without glaucoma (58 control subjects) were included. Glaucomatous eyes required manual correction more frequently than control eyes (56% vs. 32% of RNFL OCT scans; P<0.001). After manual correction in the glaucoma group, the global RNFLT decreased significantly from 61.8 to 57.5 µm (P=0.025), 50.8 to 47.2 µm (P=0.019), and 45.5 to 39.6 µm (P=0.006) for the 3.45-, 4.50-, and 6.00-mm scans, respectively. After manual correction of RNFL segmentation errors, the glaucoma diagnostic capability of the global RNFLT improved significantly; the area under the curves increased from 0.827 to 0.886 (P=0.017), 0.829 to 0.880 (P=0.033), and 0.762 to 0.846 (P=0.006) for the 3.45-, 4.50-, and 6.00-mm scans, respectively. A significant proportion of myopic eyes had RNFL segmentation errors in automated spectral-domain OCT analysis, decreasing glaucoma diagnostic capability of OCT RNFLT measurement.

In vivo exploration of retinal nerve fiber layer morphology in Parkinson's disease patients.

Thinning of the retinal nerve fiber layer (RNFL) is a recently discovered feature of Parkinson's disease (PD). Its exact pathological mechanism is yet unknown. We aimed to determine whether morphological changes of the RNFL are limited to RNFL thinning or also comprise an altered internal structure of this layer. Therefore, we investigated RNFL thickness and applied the RNFL attenuation coefficient (RNFL-AC), a novel method derived from optical coherence tomography, in PD patients and healthy controls (HCs). In this pilot study, we included 20 PD patients and 20 HCs matched for age, sex, and ethnicity. An ophthalmologist investigated all participants thoroughly, and we acquired retinal images from both eyes of each participant with a Spectralis optical coherence tomography system. We obtained both the RNFL-AC and RNFL thickness from peripapillary RNFL scans for the entire RNFL, as well as for each quadrant separately. We found no significant differences in the average RNFL-AC or the RNFL-AC of the separate retinal quadrants between PD patients and the HC group. However, compared to the HC group, PD patients had a significantly thinner RNFL in the temporal retinal quadrant. RNFL thinning was found in the temporal quadrant in PD patients without a corresponding change in the RNFL-AC. These findings suggest a reduction in the number of RNFL axons (atrophy) without other major changes in the structural integrity of the remaining RNFL.

Prevalence and Associated Factors of Segmentation Errors in the Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell Complex in Spectral-domain Optical Coherence Tomography Images.

To determine the prevalence of errors in segmentation of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) boundary in spectral-domain optical coherence tomography (SDOCT) images, and to identify factors associated with the errors. Peripapillary RNFL circle scans and macular 3-dimensional scans of consecutive cases imaged with SDOCT (RS-3000 Advance; Nidek, Gamagori, Japan) were retrospectively reviewed by a glaucoma specialist. Images with signal strength index (SSI)<6 were excluded. Threshold for segmentation failure was determined as 15 degrees in the RNFL scans and 1/24 of the scanned area in the GCC scans. Relationships between segmentation failure and clinical factors were statistically evaluated with univariable and multivariable analyses. This retrospective cross-sectional study included 207 eyes of 117 subjects (mean age, 58.5±16.5 y). Segmentation failure was found in 20.7% of the peripapillary RNFL scans, 16.6% of the 9 mm GCC scans, and 6.9% of the 6 mm GCC scans in SDOCT images. In multivariable logistic regression analyses, low SSI, large disc area, and disease type significantly correlated with RNFL segmentation failure, whereas SSI was the only baseline factor that was significantly associated with GCC segmentation failure. Although segmentation failure was common in both RNFL and GCC scans, it was less frequently observed in GCC scans. SSI, disc area, and disease type were significantly associated with segmentation failure. Predictive performance of baseline factors for failure was poor, underlining the importance of reviewing raw OCT images before using OCT parameters.