Spectral-domain Optical Coherence Tomography Instruments Research Articles

Determinants of peripapillary retinal nerve fiber layer\u2019s grayscale value in normal eyes by spectral domain optical coherence tomography

To determine and evaluate the distribution, variation, and determinants of peripapillary retinal nerve fiber layer (pRNFL) grayscale value with spectral-domain optical coherence tomography (SD-OCT) in normal eyes. In this cross-sectional study, three hundred ninety-seven normal eyes from 397 healthy Chinese adults aged 18–80 were consecutively recruited from a tertiary eye care center. An SD-OCT instrument took pRNFL imaging. We used a customized software to measure pRNFL parameters, including thickness and grayscale value. Univariable and multiple linear regression analyses were performed to examine the relationship between pRNFL grayscale value with ocular (e.g., axial length [A.L.], spherical equivalent [S.E.], intraocular pressure [IOP]), and systemic (e.g., age, sex) factors. A total of 397 eyes from 397 healthy subjects were included in the final analysis with mean (± SD) age 44.63 ± 16.43 years (range 18–80 years) and 196 (49.4%) males. The mean average of pRNFL grayscale value and thickness 164.82 ± 5.69 and 106.68 ± 8.89 μm, respectively. pRNFL grayscale value in nasal sectors (163.26 ± 9.31) was significantly lower comparing those in all other five sectors (all with p < 0.001)]. In multivariable analysis, average pRNFL grayscale value was independently correlated to older age (β = − 0.053, p = 0.002), longer axial length (β = − 0.664, p = 0.003), lower RPE grayscale value (β = 0.372, p < 0.001) and lower ImageQ (β = 0.658, p < 0.001). In this study, we provided normative SD-OCT data on the pRNFL grayscale value profile in nonglaucomatous eyes. Lower average pRNFL grayscale value was independently correlated to older age, longer axial length, lower RPE grayscale value, and lower ImageQ. These determinants should be considered when interpreting pRNFL grayscale value in glaucoma assessment.

OCT Variability Prevents Their Use as Robust Biomarkers in Multiple Sclerosis.

ObjectiveTo evaluate the agreement between the peripapillary retinal nerve fiber layer (pRNFL) and foveal thickness (FT) measurements among three different spectral domain-optical coherence tomography (SD-OCT) instruments in a sample of multiple sclerosis (MS) patients and a healthy age-matched control group.MethodsAn observational cross-sectional study with three groups: healthy subjects and MS patients w/w a previous clinical diagnosis of optic neuritis (ON) was conducted. The pRNFL and FT were measured using three different SD-OCT instruments (OCT PRIMUS 200 and OCT CIRRUS 500 SD-OCT [Carl Zeiss Meditec] and OCT 3D 2000 [Topcon]).ResultsTwenty eyes from 10 healthy subjects matched in age with MS patients without a previous history of eye disease and 62 MS eyes from 31 MS patients (29 eyes without history of ON and 33 eyes with history of ON) were enrolled. Healthy subjects and MS patients without ON did not show differences between the pRNFL and FT thickness (P>0.99) with any of the instruments. However, MS eyes with a previous episode of ON showed thinner pRNFL and FT (P<0.01). PRIMUS and CIRRUS OCT showed better agreement of the pRNLF and FT in both healthy and MS eyes. However, 3D OCT showed less agreement in the pRNFL measurement with CIRRUS in both healthy and MS eyes.InterpretationAlthough OCT is a valuable technology to improve MS patient assessment, differences between devices must be taken into account. It is necessary to create an international group that standardizes the measurement conditions and above all that provides reference bases for normal subjects.

Assessment of Retinal Microangiopathy in Chronic Kidney Disease Patients.

Introduction:Optical coherence tomography angiography (OCT-A) is a useful diagnostic tool for assessing eyes’ health in patients with chronic diseases, such as diabetes, hypertension, Parkinson’s disease and chronic kidney disease (CKD).Aim:To detect changes in macular structure and retinal vascular meshwork in the macular area and peripapillary in patients with chronic kidney disease (CKD).Methods:This cross-sectional study included 80 eyes of patients with CKD in stages 2, 3 or 4, who were followed-up in the Nephrology Clinic of University Clinical Center Sarajevo. All patients were categorized according to the stage of CKD. All patients were scanned by a high-speed 840-nm-wavelength spectral-domain optical coherence tomography instrument (RTVue XR Avanti; Optovue, Inc, Fremont, California, USA). Blood flow was detected using a split-spectrum amplitude-decorrelation angiography algorithm. A fully automated microstructural analysis of the foveal avascular zone (FAZ), FAZ perimeter, foveal vessel density in a 300-μm area around the FAZ (FD), nonflow area, flow index in superficial and deep vascular plexus, choriocapillary flow, vascular density, radial peripapillary capillary density was performed.Results:When comparing patients with CKD stage 2 and stage 3 there were no statistically significant changes in microvascular parameters on OCT angiography, as well as when comparing patients with CKD stage 3 and stage 4. But in the comparison between patients with less developed CKD (stage 2) and terminal CKD (stage 4) there was a significant difference between some microvascular parameters such as FAZ area, FAZ perimeter, choriocapillary flow.Conclusion:Many studies demonstrated that evaluation of the microvascular changes in different retinal layers using SS-OCTA may be considered as a key to assessing the systemic perfusion status. Evaluation of retinal microvasculature may ease the management and approach of patients with CKD, having in mind that the retinal and the kidney vascular network are, concerning structure, development and the function, very similar.

Optical Coherence Tomography Angiography Contributions in Classification of Nonproliferative Diabetic Retinopathy.

Introduction:To show the importance of optical coherence tomography (OCT) angiography imaging of superficial and deep capillary network in patients with non-proliferative diabetic retinopathy (NPDR), and to show the correlation between blood glucose level and changes in the foveal microvasculature.Methods:A cross-sectional study was performed on eyes with NPDR and healthy subjects using a highspeed 840-nm-wavelength spectral-domain optical coherence tomography instrument (RTVue XR Avanti; Optovue, Inc, Fremont, California, USA). Blood flow was detected using the split-spectrum amplitude-decorrelation angiography algorithm. A fully automated microstructural analysis of the foveal avascular zone (FAZ) and avascular surfaces was performed. Quantitative values from diabetic patients were compared with those of healthy subjects. Data about blood status in diabetic patients and healthy subjects were taken from patients’ medical history.Results:Size of both, FAZ and vascular dropout are significantly different between healthy patients and patients with NPDR. OCT angiography detected enlargement and distortion of the foveal avascular zone, retinal capillary dropout, and a higher number of vascular loops and microaneurysms. Sizes of FAZ and vascular dropout increase with the duration of disease. Central macular thickness (CMT) is not significantly different between healthy patients and patients with NPDR. A study has proven a positive correlation between the size of FAZ and the size of vascular dropout in superficial vascular plexus in patients that have DM over 10 years.Conclusion:A qualitative and quantitative OCT angiography approach to retinal vascular status can offer objective data on monitoring patients with non-proliferative diabetic retinopathy as well as indicate the progression of the disease.

Reproducibility of Macular Thickness Measurements in Eyes Affected by Dry Age-Related Macular Degeneration From Two Different SD-OCT Instruments.

To compare macular thickness measurement algorithms of two different spectral-domain optical coherence tomography (SD-OCT) devices in eyes affected by dry age-related macular degeneration (AMD). Patients with dry AMD and healthy volunteers from the retina clinic of the Doheny Eye Center - UCLA were imaged using two different SD-OCT devices: the RS-3000 Advance (Nidek, Padova, Italy) and the Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). All patients had been previously diagnosed with drusen or geographic atrophy due to AMD. The commercial instrument software was used to generate the macular retinal thickness measurements, and measurements were compared between devices. Eighty-five diseased eyes from 49 patients and 16 healthy control eyes from eight normal volunteers were included in this study. The macular thickness measurements generated by the two instruments in eyes with AMD differed significantly in mean retinal thickness in the foveal center subfield (257.34 μm ± 51.72 μm using the Nidek OCT vs. 238.20 μm ± 51.89 μm using the Cirrus OCT; P < .001). The mean difference in macular thickness between the two devices was 19.14 μm ± 5.84 μm for diseased eyes and 17.06 μm ± 5.28 μm in normal control eyes, and this was not statistically different between the two groups (P > .05). The macular thickness measurements in diseased eyes, as evaluated by the two different instruments, however, showed excellent correlation (r = 0.99; P < .001), with an intraclass correlation coefficient of 0.99 (95% confidence interval, 0.98-0.99). Post hoc evaluation of cases with larger differences also showed differences in foveal center selection and variabilities in boundary selection with specific pathology. Macular thickness measurements provided by the Nidek and Cirrus OCT instruments in eyes with dry AMD are highly correlated but show a consistent difference, which may allow the use of a standard correction factor to be applied to better interrelate measurements between the devices. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:410-415.].

Comparisons of foveal thickness and slope after macular hole surgery with and without internal limiting membrane peeling.

BackgroundWe have shown that the foveal contour was asymmetrical after idiopathic macular hole (MH) closure by pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling. The purpose of this study was to determine whether these morphological changes differ in eyes after PPV without ILM peeling.MethodsTen eyes of 10 patients that underwent PPV without ILM peeling and 12 eyes of 11 patients with ILM peeling were studied. The MH in all eyes was <400 µm in diameter. Six months after the PPV, the macular thickness and foveal slope around the closed MH were determined by spectral-domain optical coherence tomography. The thickness of the ganglion cell complex was measured by another spectral-domain optical coherence tomography instrument >6 months after the surgery.ResultsThe mean parafoveal retinal thickness in the non-peeled group was 367.1 µm in the nasal (N), 353.0 µm in the temporal (T), 366.9 µm in the superior (S), and 357.3 µm in the inferior (I) sectors. The T, S, and I sectors were significantly thicker than the corresponding sectors in the ILM peeled group (p=0.0008, 0.003, and 0.03, respectively). The mean ganglion cell complex was thicker not only in the N sector but also in the T sector in the non-peeled group. The mean retinal slopes in the non-peeled group (N, 40.2°; T, 37.6°; S, 41.2°; I, 39.5°) were flatter than those in the peeled group (N, 52.3°; T, 43.6°; S, 50.8°; I, 51.9°; p=0.009, 0.09, 0.008, and 0.017, respectively).ConclusionThe symmetrical fovea after MH surgery in the non-ILM peeled eyes indicates that the asymmetrical fovea after ILM peeling was probably due to the ILM peeling.

Optic Disc and Macular Imaging in Blind Eyes from Non-glaucomatous Optic Neuropathy: A Study with Spectral-domain Optical Coherence Tomography

ABSTRACTThe purpose of this study was to determine and compare the optic disc and macular thickness measurements using two spectral-domain optical coherence tomography (SD-OCT) instruments in long-standing blind eyes diagnosed with non-glaucomatous optic neuropathies (NGON). A prospective observational case-series design was used. Twelve eyes from 12 NGON patients with no light perception for at least 6 months underwent optic disc and macular imaging with Cirrus HD-OCT and Spectralis OCT. The correlation between the peripapillary retinal nerve fibre layer (PRNFL) and macular ganglion cell layer and inner plexiform layer (GCL+IPL) thicknesses, and between the duration of no light perception (NLP) and PRNFL/GCL+IPL thicknesses were determined using Spearman’s correlation analysis. The mean average PRNFL thickness was 55.9 ± 4.8 µm for Cirrus HD-OCT, which was significantly thicker than that measured by Spectralis OCT (31.9 ± 7.4 µm; p < 0.001). The mean central macular thickness on Cirrus HD-OCT was normal, but there was global thinning at the other macular areas. The mean average GCL+IPL thickness on Cirrus HD-OCT was 51.8 ± 5.8 µm. There was a good correlation between average PRNFL thickness and GCL+IPL thickness (r = 0.830, p = 0.002); however, there was no significant correlation between the duration of NLP to the average PRNFL thickness (on either instruments) or GCL+IPL thickness on Cirrus HD-OCT (p > 0.7). These results show that there was residual PRNFL thickness in NGON eyes with NLP, which varied significantly between SD-OCT instruments. The values of the residual PRNFL and GCL+IPL thicknesses in blind eyes (the “floor” effect) may be useful for prognostic purposes for patients with partial optic atrophy.

Photobleaching by Spectralis Fixation Target.

The aim of this study is to determine whether the cross-shaped fixation target in a spectral-domain optical coherence tomography instrument (Spectralis; Heidelberg Engineering) could produce a cross-shaped increase fundus autofluorescence artifact on subsequent imaging. Thirty eyes of 15 healthy volunteers (8 women and 7 men; mean [SD] age 24 [3] years) were included in the study, which was conducted between October 2015 and December 2015. In all eyes, a cross-shaped increase in macular autofluorescence with variable intensity occurred after Spectralis spectral-domain optical coherence tomography acquisition. This peculiar pattern was also detected on confocal scanning laser ophthalmoscope infrared reflectance and MultiColor imaging. Interestingly, no changes in macular fundus autofluorescence pattern were evident after optical coherence tomography acquisition with either Cirrus HD-OCT 5000 or RTVue XR Avanti. In an era characterized by extensive use of optical coherence tomography examination in clinical practice, the potential deleterious effects related to photopigments consumption by Spectralis optical coherence tomography fixation point deserve further investigation.

Optical Coherence Tomography Angiography in Diabetic Retinopathy: A Prospective Pilot Study

To evaluate how optical coherence tomography (OCT) angiography depicts clinical fundus findings in patients with diabetic retinopathy (DR). Prospective study evaluating imaging technology. Forty-seven eyes of 25 patients with DR were scanned using a high-speed 840-nm-wavelength spectral-domain optical coherence tomography instrument (RTVue XR Avanti; Optovue, Inc, Fremont, California, USA). Blood flow was detected using the split-spectrum amplitude-decorrelation angiography algorithm. Fluorescein angiography (FA) images were also obtained in all eyes and the ability to visualize microaneurysms, retinal nonperfused areas, and neovascularization was compared with that of the en face OCT angiograms. In 42 eyes, microaneurysms detected by FA near the macula appeared as focally dilated saccular or fusiform capillaries on OCT angiograms of the superficial and/or deep capillary plexus. Retinal nonperfused areas visualized by FA appeared as lesions with no or sparse capillaries on OCT angiograms. Area measurement of retinal nonperfusion near the macula in 7 eyes revealed a difference between the extent of nonperfused areas in superficial and deep plexuses. In 4 eyes, the vascular structures of neovascularization at the optic disc were clearly visualized on OCT angiograms. Decreases and re-increases of flow in new vessels were quantified in an eye treated with anti-vascular endothelial growth factor. OCT angiography can clearly visualize microaneurysms and retinal nonperfused areas and enables closer observation of each layer of the retinal capillaries. Quantitative information on new vessels can also be obtained. OCT angiography may be clinically useful to evaluate the microvascular status and therapeutic effect of treatments for DR.

Quantitative comparison of macular segmentation performance using identical retinal regions across multiple spectral-domain optical coherence tomography instruments

PurposeComparison of optical coherence tomography (OCT) segmentation performance regarding technical accuracy and clinical relevance.Methods29 eyes were imaged prospectively with Spectralis (Sp), Cirrus (Ci), 3D-OCT 2000 (3D) and RS-3000 (RS) OCTs....

Measurement of Deep Optic Nerve Complex Structures with Two Spectral Domain Optical Coherence Tomography Instruments

Purpose: To assess the usefulness of two spectral domain optical coherence tomography (SD-OCT) instruments (Cirrus, Spectralis) for evaluating optic nerve head and peripapillary structures. Methods: Images of optic nerve complex were obtained from 136 eyes of 136 patients using enhanced depth imaging technique of 2 SD-OCT instruments. Optic nerve head and peripapillary structures were investigated for their visibility and morphological features in total eyes and glaucomatous eyes. Effect factors for laminar thickness measurement were evaluated and the reproducibility of the lamina cribrosa thickness measured by the 2 OCT instruments was analyzed. Results: Lamina cribrosa thickness was better identified using Spectralis OCT in total and glaucomatous eyes. Short posterior ciliary artery (in total eyes) and peripapillary choroid (in total and glaucomatous eyes) were also better identified using Spectralis OCT (p < 0.001). A cup-disc ratio ≤ 0.6 was the significant effect factor for laminar thickness measurement (p < 0.05). Interobserver reproducibility was excellent using both OCT instruments. Intraobserver reproducibility was excellent using Spectralis OCT and moderate using Cirrus OCT. Conclusions: Spectralis OCT was better for visualizing optic nerve head and peripapillary structures and showed better reproducibility than Cirrus OCT. Thus, the Spectralis may be helpful for detecting and understanding features of the optic nerve complex. J Korean Ophthalmol Soc 2015;56(3):371-378

Spectral-domain optical coherence tomography evaluation of the cornea, retina, and optic nerve in normal horses.

To determine the feasibility of using a handheld spectral-domain optical coherence tomography (SD-OCT) instrument to characterize normal corneal, retinal, and optic nerve head anatomy in vivo in standing horses. Clinically normal horses under sedation, palpebral nerve blockage, and pharmacologically induced mydriasis were imaged with a SD-OCT instrument (Envisu SD-OCT, Bioptigen, Inc., Morrisville, NC). Radial volumes from the cornea (axial, superior, inferior, nasal, and temporal), and rectangular volumes from the retina (dorsal, ventral, nasal, and temporal) and optic nerve head were acquired. Manual measurements of the corneal layers within the five regions, retinal and nerve fiber layer thickness in the four different regions adjacent to the ONH, and vertical and horizontal axis of the optic nerve head (ONH) and optic cup (OC) were obtained using the same device. Total corneal thickness (mean ± SD) measurements were 800 ± 50, 937 ± 61, 956 ± 61, 912 ± 65, and 884 ± 68 μm for the axial, superior, inferior, nasal, and temporal regions, respectively. The highest total retinal and nerve fiber layer thickness (mean ± SD), at the level of the ONH, was found nasally 459 ± 115 and 377 ± 116 μm, respectively, followed by the temporal, dorsal, and ventral quadrants. The dimensions of the ONH and OC (mean ± SD) were 3.682 ± 0.276 and 2.175 ± 0.502 mm for the horizontal, and 3.012 ± 0.278 and 2.035 ± 0.488 mm for the vertical axis. The SD-OCT instrument employed in this study may be used on sedated horses and allows the acquisition of high-resolution images, and thickness measurements involving the cornea, retina, and optic nerve.

NEW PROFILES OF POSTERIOR POLE RETINAL THICKNESS MAP IN HEALTHY KOREAN EYES MEASURED BY SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY

To analyze posterior pole retinal thickness using the new Spectralis HRA + OCT protocol and compare two commercially available spectral-domain optical coherence tomography instruments (Spectralis HRA + OCT and Cirrus HD-OCT) in young healthy eyes. Retinal thickness in 178 young healthy eyes was measured using the volume scan mode and Posterior Pole Asymmetry Analysis of the Spectralis HRA + OCT and the macular cube 512 × 128 protocol of the Cirrus HD-OCT. Topologic differences in posterior pole retinal thickness between the two spectral-domain optical coherence tomographies were compared, and the relationship between retinal thickness and age or refractive error/axial length was assessed. Mean retinal thickness measurements in all 9 Early Treatment Diabetic Retinopathy Study Report areas were significantly greater with the Spectralis HRA + OCT than with the Cirrus HD-OCT (P < 0.001). Retinal thickness measured with the new Spectralis HRA + OCT protocol positively correlated with refractive error (P < 0.05) and negatively correlated with axial length (P < 0.05), mainly in the temporal areas. As axial length increased and refractive error decreased, retinal thickness decreased significantly at the outer temporal areas compared with the nasal areas (P < 0.05). Foveal thickness measured with the Spectralis HRA + OCT correlated significantly with refractive error (r = -0.151; P = 0.022) and axial length (r = 0.352; P < 0.001). Posterior pole retinal thickness measurements in young healthy eyes should provide more detailed standard values for diagnosing and managing retinal disease.

The Ability of Macular Parameters and Circumpapillary Retinal Nerve Fiber Layer by Three SD-OCT Instruments to Diagnose Highly Myopic Glaucoma

To compare the ability of circumpapillary retinal nerve fiber layer (cpRNFL) thickness and macular parameters obtained by three spectral-domain optical coherence tomography (SD-OCT) instruments to detect highly myopic glaucoma. In this study, 84 glaucomatous eyes, 53 normal eyes with high myopia, and 86 normal eyes (not highly myopic) were enrolled. Each participant was imaged using Cirrus, RTVue, and 3D OCT to evaluate the average and quadrant cpRNFL thicknesses. The macular retinal nerve fiber layer (mRNFL), ganglion cell layer + inner plexiform layer (GCL/IPL), and mRNFL + GCL/IPL (GCC) thicknesses were analyzed. The areas under the receiver operating characteristic curves (AUCs) were compared between the instruments. In addition, the best parameters for the AUC were compared between the cpRNFL parameters and macular parameters in each instrument. These analyses revealed similar AUCs for the average cpRNFL and GCC thicknesses between the instruments. RTVue displayed a significantly higher AUC in the nasal cpRNFL thickness than both Cirrus (P = 0.0004) and 3D OCT (P = 0.0006). 3D OCT showed higher AUCs than Cirrus in the mRNFL parameters. There were no significant differences between the best cpRNFL parameters and macular parameters in each instrument. The average cpRNFL and GCC thicknesses that were measured using these OCT instruments exhibited similar abilities for diagnosing highly myopic glaucoma, and RTVue exhibited better diagnostic abilities than Cirrus and 3D OCT for nasal cpRNFL. 3D OCT had better ability than Cirrus in the mRNFL. Both cpRNFL and GCC in each instrument were comparable, and their measurements offered good ability for diagnosing glaucoma with high myopia. (http://www.umin.ac.jp/ctr/index/htm9, UMIN000006900.).

SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING OF DRUSENOID PIGMENT EPITHELIAL DETACHMENTS

To evaluate drusenoid retinal pigment epithelial detachments (DPED) secondary to age-related macular degeneration (AMD) using spectral-domain optical coherence tomography imaging. In this prospective natural history study, eyes from patients with the diagnosis of nonexudative AMD and DPEDs were followed for at least 6 months. Eyes were scanned using the Cirrus spectral-domain optical coherence tomography instrument and the 200 × 200 A-scan raster pattern. A custom software was used to quantify volumetric changes in DPEDs and to detect the evolution and formation of geographic atrophy and choroidal neovascularization. Changes in DPED area and volume and development of the advanced forms of AMD were the main outcome. Of the 130 patients (186 eyes) with nonadvanced AMD, 11 patients (16 eyes) presented with DPEDs during the study. Mean follow-up was 18.5 months. Most DPEDs had an area exceeding 1 disk area (14 of 16 eyes) based on color fundus images with a mean area of 4.19 mm(2) (SD = 1.35) measured by spectral-domain optical coherence tomography. The mean volume at the time the DPED was diagnosed was 0.48 mm(3) (SD = 0.28). Four different patterns of progression were observed: DPEDs remained unchanged in 8 of 16 eyes (50%), DPEDs tended to increase in volume before progressing to geographic atrophy in 5 eyes (31.25%) and choroidal neovascularization in 2 eyes (12.5%), and a DPED decreased by more than 50% without progressing to geographic atrophy or choroidal neovascularization in 1 eye (6.25%). Spectral-domain optical coherence tomography imaging is able to detect subtle changes in the area and volume of DPEDs. Quantitative spectral-domain optical coherence tomography imaging of DPEDs is useful for identifying the natural history of disease progression and as a clinical tool for monitoring eyes with AMD in clinical trials.

Measurement of macular ganglion cell layer and circumpapillary retinal nerve fiber layer to detect paracentral scotoma in early glaucoma

Glaucoma patients with paracentral scotoma are at higher risk of losing central vision than those without glaucoma. The purpose of this study was to determine whether macular inner retinal layer (MIRL) measurements with spectral-domain optical coherence tomography (SD-OCT) outperform circumpapillary retinal nerve fiber layer (cpRNFL) measurements in discriminating between eyes with and without paracentral scotoma. This retrospective study included 63 early glaucomatous eyes of 63 patients with (PSI group) or without (PSF group) paracentral visual field (VF) defects. MIRL thicknesses, including macular ganglion cell complex (mGCC), macular ganglion cell layer + inner plexiform layer (mGCL+), macular RNFL (mRNFL), and cpRNFL thickness were measured using a SD-OCT instrument (3D OCT-2000). The MIRL and cpRNFL were divided into 50 grid cells and 36 sectors, respectively, which were numbered from center/temporal to periphery/nasal. Discriminating ability of the methods for number of cells/sectors with abnormal thickness (<5% of normal) and average thickness in the hemisphere corresponding to the VF defects (termed hemi-thickness) was compared by area under the receiver operating characteristics curves (AROCs). The number of abnormal nearest sectors of cpRNFL and all MIRL parameters were significantly smaller in the PSI group than in the PSF group (P ≤ 0.001-0.047), whereas no significant differences were found for average or hemi-cpRNFL thickness. The AROCs of the number of abnormal nearest cells for mGCC and mGCL+ and average hemi-thickness for mGCC, mGCL+, and mRNFL were comparable and significantly higher than those of the number of abnormal nearest sectors/cells for cpRNFL (P = 0.0002-0.0063) and mRNFL (P = 0.0003-0.0267) parameters. Regional assessment of MIRL thickness as measured by SD-OCT may potentially be an effective method for predicting central involvement of VF defects in early glaucoma.

Structure–function relationship among three types of spectral‐domain optical coherent tomography instruments in measuring parapapillary retinal nerve fibre layer thickness

To compare the relationships of parapapillary retinal nerve fibre layer (RNFL) thickness among three spectral-domain optical coherence tomography (SD-OCT) instruments with visual field sensitivity (VFS). One hundred and thirteen eyes of 113 Japanese subjects with glaucoma (mean deviation in standard automated perimetry = -8.9 ± 6.7 dB) were imaged by Cirrus, RTVue and 3D OCT. The average hemi-superior and hemi-inferior RNFL thicknesses were obtained. In addition, the structure-function relationship using two retinotopic maps that consisted of six or nine sectors was also evaluated. Decibel (dB) scale and 1/Lamert (1/L) were used to express VFS. RNFL thickness correlation with corresponding VFS in visual field sectors was compared among the three instruments. Background RNFL thickness (non-neuronal tissue) for each instrument was estimated using a linear regression model at 1/L = 0. The correlation between the average hemi-superior and hemi-inferior RNFL thickness in the three SD-OCT instruments with corresponding VFS was similar. In the analysis of retinotopic maps, 3D OCT showed a higher correlation in superotemporal sectors than RTVue, whereas RTVue had a stronger relationship in the nasal sector than Cirrus. The background RNFL thickness extrapolated was approximately 60% that of normal eyes in all the instruments. The three SD-OCT showed similar overall correspondence with VFS with a partially discordant retinotopic relationship. RNFL measured with any SD-OCT devices likely contains non-neuronal tissue, comprising 60% of its thickness.

Comparison of Geographic Atrophy Measurements from the OCT Fundus Image and the Sub-RPE Slab Image

To compare two different approaches to measuring areas of geographic atrophy (GA) using spectral-domain optical coherence tomography (SD-OCT). Fifty eyes with GA were imaged with an SD-OCT instrument. OCT fundus images and sub- retinal pigment epithelium (RPE) slab images were generated. Three graders manually drew the GA boundaries on both en face images. An automated algorithm was used to segment the GA boundaries from the sub-RPE slabs. The agreement between the three manual measurements on both OCT fundus images (ICC = .998) and sub-RPE slabs (ICC = .999) was excellent. Area measurements from OCT fundus images and sub-RPE slabs were highly correlated. The agreement between manual and automated measurements on the sub-RPE slabs was very good (ICC = .795). Both OCT fundus images and sub-RPE slab images proved useful for measuring GA in age-related macular degeneration. The automated algorithm typically provided useful measurements of GA area from the sub-RPE slabs.

Identifying the Boundaries of Retinal Pigment Epithelial Detachments Using Two Spectral-Domain Optical Coherence Tomography Instruments

To compare two spectral-domain optical coherence tomography (SD-OCT) instruments in identifying the boundaries of retinal pigment epithelium detachment (PED). 27 eyes were scanned with Cirrus and Spectralis SD-OCT instruments during a single visit. Two Cirrus scan patterns were used: the 512 × 128 and 200 × 200 covering a 6 × 6 mm (20° × 20°) area. The Spectralis scan pattern consisted of seven B-scans, averaged 51 times, covering a 30° × 5° area. The main outcome measures were the retinal thickness at the foveal center and the number of segmentation failures on the central B-scan. The Spectralis algorithm failed to follow the proper retinal contour in 25 eyes (92.6%), while the segmentation on the Cirrus instrument was successful in every central B-scan. Spectralis yielded greater retinal thickness measurements in all cases, and the average difference between Cirrus and Spectralis was 139 μm (P < .001). The intraclass correlation coefficient between the two Cirrus scan patterns was 0.998, and Cirrus versus Spectralis was 0.21. The Cirrus SD-OCT instrument identifies the appropriate segmentation boundaries in the presence PED. The Spectralis SD-OCT algorithm was unreliable in segmenting PEDs, leading to inaccurate retinal thickness measurements unless manual adjustments were performed.

Automated Detection of the Foveal Center Improves SD-OCT Measurements of Central Retinal Thickness

To investigate the performance of an automated foveal center detection algorithm on spectral-domain optical coherence tomography (SD-OCT). Fifty normal eyes and 50 eyes with early stage dry age-related macular degeneration (AMD) were analyzed. The actual scan center (SC), automatically detected foveal center (AF), and manually identified foveal center (MF) were compared. The mean of the radial distances was 89 ± 120 μm from MF to SC and 54 ± 41 μm from MF to AF for normal eyes and 179 ± 125 μm from SC to MF and 104 ± 62 μm from AF to MF for eyes with AMD. The differences were statistically significant (P < .001). The automated algorithm designed to detect the foveal center was more accurate in detecting the foveal center than relying on the fixation target of the SD-OCT instrument.