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IVOCT Has a Bright Future in the Identification of Vulnerable Plaques
摘要： Using intravascular imaging to identify the impact of statins on vulnerable plaques has a long and rich history. Intravascular ultrasound (IVUS) imaging of coronary arteries first provided a more comprehensive assessment of atherosclerotic plaques in vivo than coronary angiography. Subsequent advances in tissue characterization of gray-scale IVUS allowed observers to visually identify the composition of plaques as lipid cores, fibrous tissue, and even thick fibrous caps. Early IVUS trials demonstrated a slowing or halting of progression and even regression of atherosclerosis during statin treatment. The advent of three-dimensional (3D) IVUS image reconstructions allowed more precise characterization of a reduction in lipid volume and increases in fibrous volume as a result of high-dose statin therapy. Following the introduction of virtual histology-intravascular ultrasound (VH-IVUS), with its ability to detect various types of plaques in an automated fashion, statin therapy studies indicated a reduced external elastic membrane area and calcium volume but, surprisingly, decreased fibrous plaque volume and had no effect on necrotic core volume. An obvious question is why this meta-analysis of 9 VH-IVUS trials did not demonstrate the anticipated beneficial effects of statins. Furthermore, the major limitation with IVUS in those studies was the inability to identify changes in thin-cap fibroatheroma(s) (TCFA) thickness due to limited spatial resolution of approximately 100 mm. TCFAs are the lesions most likely to rupture and are strongly predictive of major adverse cardiovascular events.
关键词： optical coherence tomography,atherosclerosis,statin,myocardial infarction
更新于2025-09-09 09:28:46
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Large axial range frequency-domain optical low coherence interferometry
摘要： In this paper, we propose a new experimental setup to extend the measurement range of frequency-domain low coherence interferometry (FD-LCI) from 3 mm to 2 cm. The FD-LCI can be extended to the technique of frequency domain optical coherence tomography (FD-OCT) by performing additional lateral scanning. This new and simple arrangement just attaches an extra interferometer before the spectrometer in a typical FD-LCI setup. With this configuration, it is possible to overcome the dynamic range limitation of the conventional technique. This allows us to measure the optical path difference of the sample of interest, which is outside the detection range of the spectrometer, using an extra interferometer as a tuner system. In addition, this tuning allows significant minimization of the effects produced by the fall-off. The accuracy of the new system is obtained by adding the FD-LCI and the tuning micrometric translator accuracies. In our experimental setup, this value is 20 μm.
关键词： FD-LCI,interferometry,large axial range,optical coherence tomography,FD-OCT
更新于2025-09-09 09:28:46
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Caveats to Obtaining Retinal Topography With Optical Coherence Tomography
摘要： We read with great interest the article by Oh et al.1 on the assessment of retinal topography in myopic eyes using spectral domain optical coherence tomography (SD-OCT). In their article, the investigators described different characteristics of retinal topography to indicate variations in ocular shape in myopia (such as a retina sloped nasally versus temporally). Like similar prior studies using magnetic resonance imaging (MRI) to measure posterior eye shape in myopia, we agree this work in retinal topography provides important insight into classifying and risk stratifying myopic eyes. However, we would like to highlight a misconception regarding the use of posterior segment SD-OCT images for absolute retinal topography measurements. In the Discussion section, it is stated that 'The rainbow pseudo-colors in the topographic (RPE) layer image represent height from the coronal plane of the eye, with blue indicating low height and red indicating high height.' In OCT, the reference plane is not the coronal plane or any plane within the eye. Instead, the reference plane is a reference delay path length in the OCT device itself.2 Axial distance (height) within an OCT image represents sample distances relative to that reference delay in optical path length. Therefore, because the reference is in the OCT device and not in the eye itself, how the eye is positioned relative to the OCT device affects the eye’s appearance in the OCT image. For example, all three distinct subtypes of retinal sloping described in the article (nasal, middle, and temporal) can be produced from the same eye simply by moving the OCT scan beam position in the pupil slightly relative to the pupil center (see Figure). The same effect also would occur if, conversely, the subject’s eye moved relative to the OCT device. Further, OCT images of the posterior eye are distorted by scan geometry and optical artifacts as our group and others have described previously.3–5 The cumulative effect is that an OCT image of the posterior eye is not an exact spatial replica or digital 'cast' of the eye itself. Hence, when using OCT to measure the absolute topography of the posterior eye, these imaging effects must be considered to separate them from actual topographic differences present in these myopic eyes.
关键词： retinal topography,posterior eye shape,myopia,optical coherence tomography,imaging artifacts
更新于2025-09-09 09:28:46
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Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral-Domain Optical Coherence Tomography
摘要： PURPOSE. To report the retinal nerve ?ber layer (RNFL) defect volume deviation according to structural RNFL loss in RNFL thickness maps. METHODS. Retinal nerve ?ber layer defect is de?ned in RNFL thickness maps by the degree of RNFL loss. A 20% to 70% degree of RNFL loss was set with a 1% interval as the reference level for determining the boundary of RNFL defects. Each individual RNFL thickness map was compared with a normative database map and the region below the reference level was identi?ed as an RNFL defect. The RNFL defect volume was calculated by summing the volumes of each pixel inside RNFL defect. The RNFL defect volume deviation was calculated by summing the differences between the normative database and the subject’s RNFL measurements. To evaluate the glaucoma diagnostic ability, the areas under the receiver operating characteristics curves (AUCs) were calculated. RESULTS. Retinal nerve ?ber layer defect volume and RNFL defect volume deviation (0.984 and 0.986, respectively) had signi?cantly greater AUCs than all circumpapillary RNFL thickness parameters (all P < 0.001). In the early stage of RNFL loss (under 31% loss of RNFL), RNFL defect volume deviation showed better diagnostic performance than the RNFL defect volume. In multivariate analysis, RNFL defect volume and RNFL defect volume deviation were signi?cantly associated with the mean deviation in visual ?eld tests. CONCLUSIONS. Retinal nerve ?ber layer defect volume deviation is a useful tool for diagnosing glaucoma and monitoring RNFL change. In early stage of RNFL loss, RNFL defect volume deviation is more sensitive for detecting glaucoma than the RNFL defect volume measurements.
关键词： retinal nerve ?ber defect,spectral-domain optical coherence tomography,lost and remaining volume,glaucoma
更新于2025-09-09 09:28:46
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Phenotype Characteristics of Fellow Eyes in Patients With Early Onset of Neovascular Age-Related Macular Degeneration
摘要： PURPOSE. To investigate phenotype characteristics of fellow eyes in patients with early onset of neovascular age-related macular degeneration (NVAMD). METHODS. Patients with new-onset unilateral NVAMD between 50 and 65 years (n ? 57, early-onset choroidal neovascularization [CNV] group) or >80 years (n ? 47, late-onset CNV group) or with nonneovascular AMD (n ? 98, no-CNV group) were included. Fellow eyes in both CNV groups and the eyes with the more severe AMD staging in the no-CNV group were used to evaluate number and size of macular drusen, extramacular drusen (EMD), pigmentary abnormalities, and retinal pigment epithelium (RPE) atrophy on color photographs and hyperre?ective dots (HRD) and reticular pseudodrusen (RPD) on spectral-domain optical coherence tomography (SDOCT) scans. Regression analysis was used to compare groups. RESULTS. Occurrence of >20 macular drusen was more frequent in the early-onset CNV group than the late-onset CNV group (odds ratio [OR] 2.93; P ? 0.01) or the no-CNV group (OR 2.17; P ? 0.02). Retinal pigment epithelium atrophy, RPD, and HRD appeared less frequently in the early-onset CNV group than in the late-onset CNV group (RPE atrophy: OR 0.11; P ? 0.005; RPD: OR 0.04; P ? 9.38 3 10(cid:2)10, HRD: OR 0.30; P ? 0.004) and no-CNV group (RPE atrophy: OR 0.12; P ? 0.005; RPD: OR 0.40, P ? 0.03, HRD: not signi?cant). No differences were detected regarding presence of large drusen, pigmentary abnormalities, and EMD. CONCLUSIONS. A large number of macular drusen in the fellow eye appeared to be characteristic for early onset of NVAMD, whereas RPE atrophy, HRD, and RPD were more frequently present in AMD patients > 80 years. Prospective trials with patients converting to NVAMD are required to further analyze morphologic characteristics for early versus late development of advanced AMD.
关键词： reticular pseudodrusen,fellow eye,spectral-domain optical coherence tomography,neovascular age-related macular degeneration
更新于2025-09-09 09:28:46
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Retinal Neurodegeneration in Diabetic Patients Without Diabetic Retinopathy
摘要： PURPOSE. To compare the thickness of all retinal layers between a nondiabetic group and diabetic patients without diabetic retinopathy (DR). METHODS. Cross-sectional study, in which all subjects underwent an ophthalmic examination including optical coherence tomography. After automatic retinal segmentation, each retinal layer thickness (eight separate layers and overall thickness) was calculated in all nine Early Treatment Diabetic Retinopathy Study (ETDRS) areas. The choroidal thickness (CT) also was measured at five locations. Generalized additive regression models were used to analyze the data. RESULTS. A total of 175 patients were recruited, 50 nondiabetic subjects and 125 diabetic patients without DR, stratified into three groups according to diabetes duration: group I (<5 years, n = 55), group II (5–10 years, n = 39), and group III (>10 years, n = 31). Overall, groups I and III of diabetic patients had a decrease in the photoreceptor layer (PR) thickness, when compared with the nondiabetic subjects in six ETDRS areas (P < 0.0007). Patients with more recent diagnosis (group I) had thinner PR than those with moderate duration (group II). Interestingly, patients with longer known disease (group III) had the thinnest PR values. There were no overall differences in the remaining retinal parameters. CONCLUSIONS. Retinal thickness profile is not linear throughout disease duration. Even in the absence of funduscopic disease, PR layer in diabetic patients seems to differ from nondiabetic subjects, thus suggesting that some form of neurodegeneration may take place before clinical signs of vascular problems arise.
关键词： neurodegeneration,retinal layers,diabetic retinopathy,optical coherence tomography
更新于2025-09-09 09:28:46
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Pattern Recognition Analysis of Age-Related Retinal Ganglion Cell Signatures in the Human Eye
摘要： PURPOSE. To characterize macular ganglion cell layer (GCL) changes with age and provide a framework to assess changes in ocular disease. This study used data clustering to analyze macular GCL patterns from optical coherence tomography (OCT) in a large cohort of subjects without ocular disease. METHODS. Single eyes of 201 patients evaluated at the Centre for Eye Health (Sydney, Australia) were retrospectively enrolled (age range, 20–85); 8 3 8 grid locations obtained from Spectralis OCT macular scans were analyzed with unsupervised classi?cation into statistically separable classes sharing common GCL thickness and change with age. The resulting classes and gridwise data were ?tted with linear and segmented linear regression curves. Additionally, normalized data were analyzed to determine regression as a percentage. Accuracy of each model was examined through comparison of predicted 50-year-old equivalent macular GCL thickness for the entire cohort to a true 50-year-old reference cohort. RESULTS. Pattern recognition clustered GCL thickness across the macula into ?ve to eight spatially concentric classes. F-test demonstrated segmented linear regression to be the most appropriate model for macular GCL change. The pattern recognition–derived and normalized model revealed less difference between the predicted macular GCL thickness and the reference cohort (average 6 SD 0.19 6 0.92 and (cid:2)0.30 6 0.61 lm) than a gridwise model (average 6 SD 0.62 6 1.43 lm). CONCLUSIONS. Pattern recognition successfully identi?ed statistically separable macular areas that undergo a segmented linear reduction with age. This regression model better predicted macular GCL thickness. The various unique spatial patterns revealed by pattern recognition combined with core GCL thickness data provide a framework to analyze GCL loss in ocular disease.
关键词： pattern recognition,aging,optical coherence tomography,ganglion cells,image analysis (clinical)
更新于2025-09-09 09:28:46
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Optical Coherence Tomography Angiography in Familial Exudative Vitreoretinopathy: Clinical Features and Phenotype-Genotype Correlation
摘要： PURPOSE. To evaluate the microstructure of the fovea in patients with familial exudative vitreoretinopathy (FEVR) compared to healthy controls using optical coherence tomography angiography (OCTA). METHODS. In this consecutive, cross-sectional, observational case series, 41 eyes of 41 patients diagnosed as FEVR and 37 eyes in 37 control subjects were studied. OCTA was utilized to automatically measure the foveal avascular zone (FAZ) and the vessel density (VD). Inner retinal thicknesses (IRT) and central retinal thickness (CRT) were measured with the instrument caliper. Targeted next-generation sequencing was performed, and phenotype-genotype association was analyzed. RESULTS. Small FAZ was found in 31.70% (13/41) FEVR eyes but not in controls. Greater CRT and lower super?cial foveal VD were noted in FEVR patients. FAZ is negatively correlated with IRT. Persistence of the inner retinal layer (IRL) in fovea was present in 48.78% (20/41) FEVR eyes but not found in controls. Zero percent (0/10) of patients with the low-density lipoprotein receptor-related protein 5 (LRP5) mutation, 50% (1/2) with the frizzled-4 (FZD4) mutation, and 66.67% (3/4) with the tetraspanin-12 (TSPAN12) mutation had preserved foveal IRL and small FAZ. CONCLUSIONS. Our data indicate FEVR status is associated with a signi?cantly smaller FAZ, decreased vascular density in both the super?cial and deep layers of parafoveal area, a thicker fovea, and an abnormally preserved IRL in fovea. In addition, patients with the LRP5 mutation had a milder phenotype than those with the FDZ4 or TSPAN12 mutations. These novel ?ndings could provide insight into the understanding of the pathogenesis of FEVR.
关键词： phenotype-genotype correlation,optical coherence tomography angiography,familial exudative vitreoretinopathy
更新于2025-09-09 09:28:46
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Longitudinal Assessment of Retinal Structure in Achromatopsia Patients With Long-Term Follow-up
摘要： To longitudinally characterize structural retinal changes in achromatopsia (ACHM) over extended follow-up. Fifty molecularly confirmed ACHM subjects underwent serial spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) imaging. Foveal structure on SD-OCT was graded and compared for evidence of progression, and foveal total retinal thickness (FTRT) and outer nuclear layer (ONL) thickness were serially measured. FAF patterns were characterized and compared over time. Mean SD-OCT follow-up was 61.6 months (age range at baseline, 6–52 years). Forty-five of the subjects had serial FAF (mean follow-up: 48.5 months). Only 6 (12%) of the subjects demonstrated qualitative change on serial foveal SD-OCT scans. Among the entire cohort, there was no statistically significant change over time in FTRT (P ? 0.2459) or hyporeflective zone (HRZ) diameter (P ? 0.3737). There was a small—but statistically significant—increase in ONL thickness (P ? 0.0084). Three different FAF patterns were observed: centrally increased FAF (13/45), normal FAF (14/45), and well-demarcated reduced FAF (18/45), with the latter group displaying a small gradual increase in the area of reduced FAF of 0.055 mm2 over 43.4 months (P ? 0.0011). This longitudinal study of retinal structure in ACHM represents the largest cohort and longest follow-up period to date. Our findings support the presiding notion that ACHM is essentially a stationary condition regarding retinal structure, and any change over time is likely to be small, slow, and variable across patients. This may potentially afford a wider window for therapeutic intervention.
关键词： gene therapy,achromatopsia,retinal dystrophy,optical coherence tomography
更新于2025-09-09 09:28:46
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An update on inflammatory choroidal neovascularization: epidemiology, multimodal imaging, and management
摘要： Inflammatory choroidal neovascular membranes are challenging to diagnose and manage. A number of uveitic entities may be complicated by the development of choroidal neovascularization leading to a decrease in central visual acuity. In conditions such as punctate inner choroidopathy, development of choroidal neovascularization is extremely common and must be suspected in all cases. On the other hand, in patients with conditions such as serpiginous choroiditis, and multifocal choroiditis, it may be difficult to differentiate between inflammatory choroiditis lesions and choroidal neovascularization. Multimodal imaging analysis, including the recently introduced technology of optical coherence tomography angiography, greatly aid in the diagnosis and management of inflammatory choroidal neovascularization. Management of these neovascular membranes consists of anti-vascular growth factor agents, with or without concomitant anti-inflammatory and/or corticosteroid therapy.
关键词： Posterior uveitis,angiography,Choroiditis,Uveitis,Fluorescein angiography,Optical coherence tomography angiography,EDI-OCT,Indocyanine green,Inflammatory choroidal neovascularization
更新于2025-09-09 09:28:46