Optical Coherence Tomography Analysis Research Articles

Between-eye correlation of ocular parameters

ObjectiveIt is accepted that ocular parameters are more correlated with the fellow eye. This poses a challenge in ophthalmic research. There is a relative scarcity of data concerning the extent of correlation. The aim of this study was to analyze and quantify the correlation of different ocular parameters. DesignHistorical registry analysis. ParticipantsAll patients examined in a 10-year period (2011–2021) in one academic tertiary medical centre in central Israel. MethodsData from optical coherence tomography examinations and biometry of a single examination of both eyes taken at the same time from each patient was included. Pearson's r values were calculated to estimate the extent of correlation. ResultsA total of 17,212 patients were included. Mean age was 73 ± 12.7 years, and 54.5% were female. All examined parameters were highly statistically significantly correlated between eyes (all with p < 0.1 × 10–36), whereas the strength of correlation differed. Very weak correlation was seen in central macular thickness (r = 0.189), and a weak correlation was seen in anterior-chamber depth (r = 0.379) and retinal nerve fibre layer thickness (r = 0.479). A strong correlation was seen in central corneal thickness (r = 0.754), and a very strong correlation was seen in axial length (r = 0.900). ConclusionsIn a retrospective analysis of optical coherence tomography and biometry measurements of >10,000 patients, all examined parameters were highly statistically significantly correlated. Correlation magnitude varied, with structural characteristics more correlated than functional ones. Including both eyes in an outcome analysis likely will introduce bias. We recommend adjusting for inter-eye correlation in all studies assessing ocular outcome measures.

LHON spectrum disorder: Phenotype and genes

Leber hereditary optic neuropathy (LHON) is an inherited optic neuropathy primarily affecting young male with subacute bilateral visual loss. Clinically it is characterized by central scotoma, discromatopsia, and usually permanent central visual loss.This disease has a typical optic disc appearance at fundus examination of pseudoedema and microangiopathy which characterize the asymptomatic and subacute phases of the disease. Optic disc atrophy follows in the chronic phase.When the disease manifests, the preferential involvement of papillomacular fibres and macular retinal ganglion cell (RGC) damage are evident. These clinical features combined with the ophthalmoscopic pattern create the framework that make the disease unique.Primary point mutations of mitochondrial DNA (mtDNA) have been described as the genetic cause of the disease in about 90% of cases. Recently, new autosomal recessive DNA mutations have been reported in patients affected by subacute visual loss associated with a clinical picture resembling LHON.We herein describe the phenotype of 6 patients in which whole‐exome sequencing identified variants in the MECR gene in 2 probands of the same pedigree, in the NDUFAF4 gene in one patient, and mutation in the nuclear gene DNAJC30 in 3 patients. The 3 male probands with DNAJC30 mutation presented the typical LHON clinical picture with subacute loss of vision at an adult age in 2 cases and at a childhood age in one case. The pattern of visual loss with central scotoma and discromatopsia was associated with pseudoedema and microangiopathy at fundus appearance. Optical coherence tomography (OCT) analysis showed in both acute and asymptomatic family members the swelling of fibres while in the dynamic and chronic stages a progressive thinning of fibres. Visual recovery was detected in the younger patient and, partially, in one of adult patient.The 3 other patients carrying the MECR and NDUFAF4 gene variants showed a particular course of the disease characterized by a childhood onset of visual loss followed by a recurrence of visual loss at an adult age. The childhood onset was insidious in one case and subacute in the other 2 cases (about 6 years of age).OCT analysis demonstrated in the insidious case the temporal thinning of fibres and the macular RGC atrophy followed by swelling of fibres during the recurrence.In the differential diagnosis of inherited optic neuropathies with clinical presentation resembling LHON we should take into consideration the recessive form with mutations in the DNAJC30 gene which appears to overlap the mtDNA LHON disease. Moreover, clinical patterns resembling LHON with recurrence of visual loss represent another form of LHON with unique clinical presentation associated with variants in the MECR and the NDUFAF4 genes. These new clinical and genetic patterns enlarge the spectrum of LHON disease.

Drug-Coated Balloon for de-novo Coronary Artery Lesions Exceeding 2.5 mm in Diameter: Optical Coherence Tomography Analysis and Clinical Follow-Up.

To investigate the precise changes in the lumen and lesions, and clinical outcomes after DCB treatment for de-novo coronary lesions exceeding 2.5 mm in diameter through a detailed analysis of OCT. This is a prospective study including 53 consecutive patients with 55 de-novo coronary lesions, who underwent DCB angioplasty-only between January 2021 and April 2022. Quantitative coronary angiography (QCA) and OCT were performed before percutaneous coronary interventions (PCI), immediately after PCI, and at 6-9 months follow-up after PCI. Target lesion failure (TLF) was the primary endpoint of the present study. Multivariate logistic regression analysis was performed to identify the predictors or risks for late lumen enlargement (LLE). A total of 52 patients were successfully treated with DCB. The median follow-up was 7 months, and the incidence of TLF was 7.5%. After the DCB procedure, 43 patients had their scheduled angiographic and OCT examination. QCA demonstrated that the late lumen loss was -0.79 ± 0.28 mm. OCT demonstrated LLE in 79.1% and dissection healing in 65.1% of lesions. After multivariable logistic analysis, type B dissection (odds ratio [OR] 2.92, 95% confidence interval [CI] 1.34-7.41, p = 0.037) was found to be a predictor of LLE, but lipid plaque (OR 0.09, 95% CI 0.01-0.63, p = 0.015) was a risk of LLE. This is the first and largest prospective study to assess the outcomes of DCB treatment for de-novo coronary lesions exceeding 2.5 mm in diameter and the detection of significant vessel enlargement and dissection healing guide by OCT. DCB could be a novel, safe and effective treatment for de-novo coronary lesions exceeding 2.5 mm in diameter through a detailed analysis of OCT.

Reviving the Role of Optical Coherence Tomography and Visual Field Analysis as Investigative Tools for Diagnosis of Primary Open-Angle Glaucoma in Rural Tertiary Care Centre

Background: Glaucoma is the second most common cause of blindness globally and is characterised by raised intraocular pressure, optic disc cupping, and visual field defects. However, advanced imaging modalities such as optical coherence tomography (OCT) can pick up early changes. Our study aims to examine the role of OCT for the early diagnosis of primary open-angle glaucoma (POAG), its correlation with standard automated perimetry, and the diagnostic efficiency of both in POAG patients at a rural tertiary care centre in the Chengelpet District. Materials and Methods: This was a prospective observational study comparing the quantitative measurement of RNFL using OCT with functional loss analysed using the Automated Perimetry Humphrey Visual Field Analyzer in patients with POAG visiting the tertiary health centre in the Chengelpet district in Tamil Nadu. The study was conducted in 92 eyes of 50 patients diagnosed with POAG for 15 months from March 2022 to May 2023. Results: Of the 92 eyes of 50 patients, 26 were male patients and 24 were female patients. In total, 21 eyes had no demonstrable visual field defect, 49 eyes had single hemifield defect and 22 eyes had both hemifield defect. The area under the receiver operator characteristic curve for OCT RNFL layer measurement in patients diagnosed with visually confirmed ONH changes was 1.00, which was highly significant (P value = 0.01) and correlated well with the type of visual field defect with Humphrey's automated perimetry, suggesting significant correlation between the two. OCT-RNFL measurements are better diagnostic tests than standard automated perimetry for the early detection of glaucoma. Conclusion: Both OCT RNFL and Humphrey's automated visual field analysis play a most crucial role as an investigative modality for early diagnosis of POAG; however, OCT has an added advantage of detecting early glaucoma changes even without visible field changes and hence useful for very early detection of POAG in a tertiary care centre.

An Analysis of Optic Disc Parameters in Patients with Peripheral Retinal Tears Following Acute Posterior Vitreous Detachment: A Cross-Sectional Study.

To investigate association between optic disc parameters analyzed by optical coherence tomography (OCT) and occurrence of peripheral retinal tears in patients with symptomatic posterior vitreous detachment (PVD). This cross-sectional study enrolled 75 patients with symptoms of acute PVD, who were allocated into two groups based on whether a peripheral retinal tear occurred or not. When comparing the average retinal nerve fiber layer (RNFL) thickness (μm) between retinal tear and control groups, it was shown that patients with a retinal tear have a significantly higher (87.18 [95% confidence interval (CI), 84.47 to 89.9] vs 81.14 [95% CI, 77.81 to 84.46], P = 0.005) average RNFL thickness. Furthermore, we observed a significant difference (0.13, 0.06 to 0.22 vs 0.07, 0.04 to 0.1, P = 0.036, Mann-Whitney U-test) in the size of cup volume (mm3) between the tear and control groups, respectively. Linear regression showed a significant decrease (P = 0.029) in average RNFL thickness with increasing age, but without a significant difference between the two groups. There was no statistically significant difference between the tear and control groups in terms of rim area, disc area, and average cup-to-disc ratio. Patients with a higher average RNFL thickness and larger cup volume measured by OCT were more prone to develop a peripheral retinal tear. Increased peripapillary average RNFL thickness due to trauma and subsequent inflammation, possibly related to the more adherent posterior hyaloid membrane to the retina, may also indicate strengthened adhesions in the areas of the peripheral retina where retinal tears occur. OCT analysis of the optic nerve head may be used in everyday clinical practice as a predictor of the development of peripheral retinal tears in patients with symptomatic PVD.

A review of retinal analysis by OCT in murine models Alzheimer's disease

Aims/Purpose: The use of murine models of Alzheimer's disease (AD) in the study of its pathophysiology is essential. In addition to a histological study of the retina, optical coherence tomography (OCT) allows a cost‐effective in vivo analysis of the retina. However, there is no standardization in the use of OCT in murine models of AD, leading to significant variations in study results. A review of the literature on murine models of AD analysed by OCT has been carried out. The characteristics of the animal model, the types of OCT, the retinal sectors analysed, the segmentation layers and the software used for segmentation were examined.Methods: We performed a literature search up to April 2023 using “MESH” terms in PubMed. The terms used were: “Alzheimer's mouse model”, “Optical Coherence Tomography”, “retinal optical coherence tomography” … as well as their combinations. We filter the articles by author criteria: the terms had to be in the title, in the abstract or in the article and they should be written in English or Spanish. Finally, 76 articles were used to the manuscript.Results: In comparison to studies using OCT in AD patients, only fourteen studies have utilized this technique to examine the retinas of murine AD models. Six different models, both first and second generation, were analysed, with most featuring presenilin mutations. There is no consensus regarding the measuring instrument, retinal area analysed, segmentation techniques, or software employed for analysis. Although some authors used the same OCT device, variations in other parameters hinder direct result comparison.Conclusions: It is essential to establish a unified criteria for OCT analysis of the retina in murine models of AD. This would allow the comparison of results and the establishment of measurement protocols. The use of OCT to understand the pathophysiology of AD would facilitate the longitudinal analysis of the disease and the possible identification of biomarkers.

Intraocular pressure increase after Nd:YAG laser capsulotomy and anterior segment optical coherence tomography analysis.

This study is to determine whether post-procedure intraocular pressure (IOP) increase is associated with the anterior chamber angle in cases of Neodymium: yttrium-aluminum garnet (Nd: YAG) laser capsulotomy. The study included 51 eyes with posterior capsule opacification. Initial IOP values of the patients were compared with IOP values without intraocular pressure-lowering administration at the end of the 1st hour, 1st day, 3rd day, and 7th day after Nd:YAG laser capsulotomy. The anterior segment angle configuration was evaluated using anterior segment optical coherence tomography analysis without dilatation before the procedure. The anterior chamber angle (ACA) and angle opening distances of 500 and 750 μm (AOD500 and AOD750) in the nasal and temporal quadrants were examined. The mean pre-laser IOP value only increased significantly at 1st hour post-laser (13.02 ± 3.02 mmHg vs 14.16 ± 4.07 mmHg, p = 0.016). In eyes with ACA below 40° in both the nasal and temporal quadrants, mean IOP increased significantly at 1st hour post-laser (p = 0.025 and p = 0.032, respectively), while it was not significant in eyes with ACA above 40° (p > 0.05). No correlation was found between ACA, AOD500, and AOD750 values and IOP changes at the first hour (p > 0.05). Except for the first hour after Nd:YAG laser capsulotomy, no significant increase in IOP was observed. This elevation was higher in eyes with ACA less than 40°. In patients with a narrow ACA, first-hour follow-up may be beneficial in terms of susceptibility to increased IOP.

Comparison of Patterns of Structural Progression in Primary Open Angle Glaucoma and Pseudoexfoliation Glaucoma.

Primary open angle glaucoma and pseudoexfoliation glaucoma showed different progression patterns of the retinal nerve fiber layer and ganglion cell-inner plexiform layer thinning in OCT-guided progression analysis. To compare the patterns of progression of retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thinning by guided progression analysis (GPA) of optical coherence tomography (OCT) in primary open angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG). The progression of RNFL and GCIPL thinning was assessed by the GPA of Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). By overlaying the acquired images of the RNFL and GCIPL thickness-change maps, the topographic patterns of progressive RNFL and GCIPL thinning were evaluated. The rates of progression of RNFL and GCIPL thinning were analyzed and compared between patients with POAG and those with PXG. Of the 248 eyes of 248 patients with POAG (175 eyes of 175 patients) or PXG (73 eyes of 73 patients) enrolled, 156 POAG eyes and 48 PXG eyes were included. Progressive RNFL thinning was significantly more common in PXG than in POAG ( P =0.005). According to the RNFL progression-frequency maps, progression appeared mainly in the superotemporal and inferotemporal areas in POAG, whereas it had invaded more into the temporal area in PXG. According to the GCIPL maps, progression was most common in the inferotemporal area in both POAG and PXG. The average progression rate of GCIPL thinning was faster in PXG than in POAG ( P =0.013), and when analyzed in 2 halves (superior/inferior), the progression rate of the inferior half was faster in PXG than in POAG ( P =0.011). OCT GPA showed progression patterns of RNFL and GCIPL thinning in POAG and PXG. Understanding the specific patterns of progressive RNFL and GCIPL thinning according to glaucoma type may prove helpful to glaucoma-patient treatment and monitoring.

A new convolutional neural network based on combination of circlets and wavelets for macular OCT classification

Artificial intelligence (AI) algorithms, encompassing machine learning and deep learning, can assist ophthalmologists in early detection of various ocular abnormalities through the analysis of retinal optical coherence tomography (OCT) images. Despite considerable progress in these algorithms, several limitations persist in medical imaging fields, where a lack of data is a common issue. Accordingly, specific image processing techniques, such as time–frequency transforms, can be employed in conjunction with AI algorithms to enhance diagnostic accuracy. This research investigates the influence of non-data-adaptive time–frequency transforms, specifically X-lets, on the classification of OCT B-scans. For this purpose, each B-scan was transformed using every considered X-let individually, and all the sub-bands were utilized as the input for a designed 2D Convolutional Neural Network (CNN) to extract optimal features, which were subsequently fed to the classifiers. Evaluating per-class accuracy shows that the use of the 2D Discrete Wavelet Transform (2D-DWT) yields superior outcomes for normal cases, whereas the circlet transform outperforms other X-lets for abnormal cases characterized by circles in their retinal structure (due to the accumulation of fluid). As a result, we propose a novel transform named CircWave by concatenating all sub-bands from the 2D-DWT and the circlet transform. The objective is to enhance the per-class accuracy of both normal and abnormal cases simultaneously. Our findings show that classification results based on the CircWave transform outperform those derived from original images or any individual transform. Furthermore, Grad-CAM class activation visualization for B-scans reconstructed from CircWave sub-bands highlights a greater emphasis on circular formations in abnormal cases and straight lines in normal cases, in contrast to the focus on irrelevant regions in original B-scans. To assess the generalizability of our method, we applied it to another dataset obtained from a different imaging system. We achieved promising accuracies of 94.5% and 90% for the first and second datasets, respectively, which are comparable with results from previous studies. The proposed CNN based on CircWave sub-bands (i.e. CircWaveNet) not only produces superior outcomes but also offers more interpretable results with a heightened focus on features crucial for ophthalmologists.

Stripping of the Posterior Hyaloid for the Treatment of Vitreomacular Traction.

To describe and evaluate the effectiveness of stripping the posterior hyaloid as vitreomacular traction treatment. This prospective, consecutive, interventional study examined 10 eyes of 10 patients who underwent vitrectomy for vitreomacular traction. The best-corrected visual acuity improved from 20/63 (0.5 ± 0.18 logMAR) preoperatively to 20/36 (0.25 ± 0.15 logMAR) 3 months after the surgeries. Optical coherence tomography analysis showed a reduction of the mean foveal thickness from 462 ± 82 µ to 372 ± 28 µ at 3-month follow-up in all the eyes. No postoperative complications were reported. Stripping of the posterior hyaloid for the treatment of vitreomacular traction could improve the symptoms and visual acuity of patients, alleviating the traction on the macula and avoiding secondary retinal damage as macular hole formation.

Detection and agreement of event-based OCT and OCTA analysis for glaucoma progression.

To examine event-based glaucoma progression using optical coherence tomography (OCT) and OCT angiography (OCTA). In this retrospective study, glaucoma eyes with ≥2-year and 4-visits of OCT/OCTA imaging were included. Peripapillary capillary density (CD) and retinal nerve fibre layer thickness (RNFL) were obtained from 4.5 mm × 4.5 mm optic nerve head (ONH) scans. Event-based OCT/OCTA progression was defined as decreases in ONH measurements exceeding test-retest variability on ≥2 consecutive visits. Visual field (VF) progression was defined as significant VF mean deviation worsening rates on ≥2 consecutive visits. Inter-instrument agreement on progression detection was compared using kappa(κ) statistics. Among 147 eyes (89 participants), OCTA and OCT identified 33(22%) and 25(17%) progressors, respectively. They showed slight agreement (κ = 0.06), with 7(5%) eyes categorized as progressors by both. When incorporating both instruments, the rate of progressors identified increased to 34%. Similar agreement was observed in diagnosis- and severity-stratified analyses (κ < 0.10). Compared to progressors identified only by OCT, progressors identified only by OCTA tended to have thinner baseline RNFL and worse baseline VF. VF progression was identified in 11(7%) eyes. OCT and VF showed fair agreement (κ = 0.26), with 6(4%) eyes categorized as progressors by both. OCTA and VF showed slight agreement (κ = 0.08), with 4(3%) eyes categorized as progressors by both. OCT and OCTA showed limited agreement on event-based progression detection, with OCT showing better agreement with VF. Both OCT and OCTA detected more progressors than VF. OCT and OCTA may provide valuable, yet different and complementary, information about glaucoma progression.

Non-flow limiting non-culprit plaque characteristics in patients presenting with STEMI versus NSTEMI

Abstract Background Non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) are often considered distinct clinical entities. Although differences in culprit plaque characteristics have been described extensively, less is known about differences in non-culprit (NC) plaque characteristics. Purpose To compare plaque characteristics of fractional flow reserve (FFR)-negative NC lesions as assessed by optical coherence tomography (OCT) in STEMI and NSTEMI patients. Methods PECTUS-obs is a prospective, observational study in which 438 patients presenting with STEMI or NSTEMI underwent OCT of any intermediate FFR-negative NC lesion (defined as a FFR &amp;gt;0.80) after treatment of the infarct related artery. Quantitative and qualitative OCT analyses were performed by an independent core laboratory. A high risk plaque (HRP) was defined as the presence of ≥2 of the following prespecified criteria: 1) a lipid arc ≥90°, 2) a minimal fibrous cap thickness &amp;lt;65 µm, or 3) either cap rupture or thrombus presence. In the present sub-analysis, lesion-level plaque characteristics were compared between patients presenting with STEMI versus NSTEMI while accounting for within-patient clustering and correcting for prespecified clinical variables (age, history of myocardial infarction, diabetes, and estimated glomerular filtration rate (eGFR)). Results Among 420 patients with at least one analyzable OCT, 217 (51.7%) presented with STEMI and 203 (48.3%) with NSTEMI. Patients with STEMI were younger (mean age 62±10 vs 65±11 years, p=0.004) and less frequently had diabetes (11.1% vs 18.2%, p=0.037) and hypercholesterolemia (31.8% vs 41.6%, p=0.038). Baseline mean eGFR (84±19 vs 75±19 ml/min, p&amp;lt;0.001) and low density lipoprotein-cholesterol levels (3.2±1.2 vs 2.9±1.2, p=0.010) were higher in STEMI patients with fewer of these patients using lipid lowering therapy (18.9% vs 33.0%, p&amp;lt;0.001) before enrollment. A total of 494 NC lesions were analyzed, which were equally distributed in number and location between groups. The mean fractional flow reserve was 0.89±0.05 and was comparable between groups (p=0.26). Patients with STEMI had a smaller minimal lumen area (2.56±1.48 vs 2.84±1.58 mm2, p=0.031) and minimal lumen diameter (1.47±0.44 vs 1.55±0.45 mm, p=0.026) with a subsequent larger percentage area stenosis (64±15 vs 61±17%, p=0.022). Lipid plaques were more common in STEMI patients (81.7% vs 70.7%, p=0.006) and the maximal lipid arc more frequently was ≥90º (79.0% vs 69.0%, p=0.018). There was no difference in the presence of plaque ruptures (8.3% vs 11.2%, p=0.31) or HRP (32.9% vs 29.3%, p=0.40), whereas macrophage accumulation was more prevalent in STEMI patients (27.8% vs 18.2%, p=0.040). Conclusions FFR-negative NC lesions in patients with STEMI have smaller luminal dimensions, and more frequently harbor lipid plaques and macrophage accumulation. No difference was observed in the prevalence of HRP or plaque rupture.

Twelve-months vessel healing profile following the novel resorbable magnesium scaffold implantation: an intravascular OCT analysis of the BIOMAG-I trial

Abstract Background The first-in-human trial of the latest resorbable magnesium scaffold (RMS), DREAMS 3G, showed favorable clinical and angiographic outcomes up to 6-months. An intravascular optical coherence tomography (OCT) assessment of the vascular healing profile at 6 months and 12 months follow-up may serve as additional supportive evidence for device safety and efficacy. Purpose The aim of this study was to evaluate the vessel healing process by quantifying the presence of strut protrusion (SP) and strut degradation following DREAMS 3G implantation as per intravascular OCT imaging. Methods Patients from the BIOMAG-I trial who underwent OCT imaging at both 6- and 12-months were deemed eligible. This resulted in the inclusion of a total of 51 patients and 52 lesions in the current analysis. The acquired intravascular imaging data were evaluated every 1 mm to visualize and quantify the SP and the number of visible struts at 6- and 12-months. In addition, we investigated the potential impact of SP on mean and minimum lumen area (mm2) at both time point. Results At 12 months, the mean SP area was significantly smaller in comparison to 6 months follow-up (1.87±2.22 mm2 at 6 months vs. 0.99±1.27 mm2 at 12 months, p&amp;lt;0.001). There was a positive correlation between SP area and mean lumen area at both 6 months (p&amp;lt;0.001) and 12 months (p=0.014) follow-up. Similarly, a positive correlation was observed between SP area and minimum lumen area up to 6 months (p=0.006 at 6 months, p=0.323 at 12 months). The number of visible struts was 6.44±7.59 at 6 months and 1.79±0.85 at 12 months (p&amp;lt;0.001). Conclusion The SP area was larger in lesions with greater lumen area following the implantation of the novel RMS. The observed SP area was significantly smaller at 12 months in comparison to 6 months follow-up. These results suggest that the presence of SP is part of a favorable vascular healing process following the treatment with the latest resorbable magnesium scaffold.

Simultaneous alignment and surface regression using hybrid 2D–3D networks for 3D coherent layer segmentation of retinal OCT images with full and sparse annotations

Layer segmentation is important to quantitative analysis of retinal optical coherence tomography (OCT). Recently, deep learning based methods have been developed to automate this task and yield remarkable performance. However, due to the large spatial gap and potential mismatch between the B-scans of an OCT volume, all of them were based on 2D segmentation of individual B-scans, which may lose the continuity and diagnostic information of the retinal layers in 3D space. Besides, most of these methods required dense annotation of the OCT volumes, which is labor-intensive and expertise-demanding. This work presents a novel framework based on hybrid 2D–3D convolutional neural networks (CNNs) to obtain continuous 3D retinal layer surfaces from OCT volumes, which works well with both full and sparse annotations. The 2D features of individual B-scans are extracted by an encoder consisting of 2D convolutions. These 2D features are then used to produce the alignment displacement vectors and layer segmentation by two 3D decoders coupled via a spatial transformer module. Two losses are proposed to utilize the retinal layers’ natural property of being smooth for B-scan alignment and layer segmentation, respectively, and are the key to the semi-supervised learning with sparse annotation. The entire framework is trained end-to-end. To the best of our knowledge, this is the first work that attempts 3D retinal layer segmentation in volumetric OCT images based on CNNs. Experiments on a synthetic dataset and three public clinical datasets show that our framework can effectively align the B-scans for potential motion correction, and achieves superior performance to state-of-the-art 2D deep learning methods in terms of both layer segmentation accuracy and cross-B-scan 3D continuity in both fully and semi-supervised settings, thus offering more clinical values than previous works.

Retinal Findings and Cardiovascular Risk: Prognostic Conditions, Novel Biomarkers, and Emerging Image Analysis Techniques.

Many retinal diseases and imaging findings have pathophysiologic underpinnings in the function of the cardiovascular system. Myriad retinal conditions, new imaging biomarkers, and novel image analysis techniques have been investigated for their association with future cardiovascular risk or utility in cardiovascular risk prognostication. An intensive literature search was performed to identify relevant articles indexed in PubMed, Scopus, and Google Scholar for a targeted narrative review. This review investigates the literature on specific retinal disease states, such as retinal arterial and venous occlusions and cotton wool spots, that portend significantly increased risk of future cardiovascular events, such as stroke or myocardial infarction, and the implications for personalized patient counseling. Furthermore, conditions diagnosed primarily through retinal bioimaging, such as paracentral acute middle maculopathy and the newly discovered entity known as a retinal ischemic perivascular lesion, may be associated with future incident cardiovascular morbidity and are also discussed. As ever-more-sophisticated imaging biomarkers and analysis techniques are developed, the review concludes with a focused analysis of optical coherence tomography and optical coherence tomography angiography biomarkers under investigation for potential value in prognostication and personalized therapy in cardiovascular disease.

Retinal changes in generalized anxiety disorder patients.

Optical coherence tomography (OCT) is a method that allows high-resolution cross-sectional imaging of biological tissues. It was suggested that changes in the cranial structure or functions would be reflected in the retina. OCT has been an important method in the diagnosis and follow-up of diseases via morphometric or quantitative retinal measurements. Free radicals, inflammatory processes, and neurotransmission disorders play a role in the etiology of generalized anxiety disorder (GAD). The study aimed to demonstrate the retinal changes in GAD patients due to neurodegeneration based on the comparison of the OCT data of the GAD patients and controls, and the differences between OCT findings of GAD patients and those of controls. The study group included 21 GAD patients. The control group included 21 individuals without any known psychiatric or organic disease, including eye diseases. There was a statistically significant difference between the macular volumes (MV) of the GAD and control groups, the macular volume was lower in the GAD group. There were positive correlations between BDI scores and MV, GCLT, RNFLT-i, RNFLT-n, between BAE scores and (RNFLT-n), and between the CGI severity scale scores and MV, RNFLT-n, and RNFLT-t. OCT analysis of the GAD patients demonstrated that MV values were lower when compared to the control group. Patients with GAD should be screened for these retinal changes. OCT, a simple, non-invasive, and relatively inexpensive method could be employed as a supplementary method in the follow-up of GAD patients.

Diurnal variation of optical coherence tomography–based macular fluid in exudative age-related macular degeneration

BackgroundSignificant diurnal fluctuation of optical coherence tomography (OCT)-based macular fluid occurs in patients with several macular conditions including diabetic macular edema (DME) and cystoid macular edema due to retinal venous occlusion (RVO). OCT imaging and analysis of macular fluid status plays a central role in clinical management of exudative age-related macular degeneration (eAMD), however diurnal variation of eAMD OCT findings has not yet been formally studied. Herein, we investigate whether clinically meaningful fluctuation of OCT-based macular fluid occurs in patients with eAMD.MethodsProspective observational study. Patients with eAMD and intra- and/or sub-retinal fluid on early AM OCT were enrolled to receive two consecutive OCT scans at least four hours later. Retinal layers were manually segmented on all OCT rasters and AM-to-PM and PM-to-PM image pairs were analyzed for total retinal and neurosensory retinal volume changes within the central 1 and 3 mm ETDRS subfields. Finally, two masked retinal specialists analyzed all OCT image pairs for qualitative differences that may impact clinical management.Results21 patients with eAMD and fluid on OCT were recruited between January 2020 and November 2021. There was no mean difference between AM and PM central 3 mm total retinal volume (p = 0.56), central 3 mm neurosensory retinal volume (p = 0.25), central 1 mm total retinal mean thickness (p = 0.96), or central 1 mm neurosensory retinal mean thickness (p = 0.63), nor were any differences identified in PM-to-PM control comparisons. Qualitative analysis by two masked experts identified no clinically significant differences between any AM-to-PM OCT image pairs.ConclusionsNo significant diurnal variation in OCT-based macular fluid or thickness was identified in patients with eAMD, either quantitatively or qualitatively.

Spectroscopic optical coherence tomography at 1200nm for lipid detection.

Spectroscopic analysis of optical coherence tomography (OCT) data can yield added information about the sample's chemical composition, along with high-resolution images. Typical commercial OCT systems operate at wavelengths that may not be optimal for identifying lipid-containing samples based on absorption features. The main aim of this study was to develop a 1200nm spectroscopic OCT (SOCT) for the classification of lipid-based and water-based samples by extracting the lipid absorption peak at 1210nm from the OCT data. We developed a 1200nm OCT system and implemented a signal processing algorithm that simultaneously retrieves spectroscopic and structural information from the sample. In this study, we validated the performance of our OCT system by imaging weakly scattering phantoms with and without lipid absorption features. An orthogonal projections to latent structures-discriminant analysis (OPLS-DA) model was developed and applied to classify weakly scattering samples based on their absorption features. The OCT system achieved an axial resolution of and a sensitivity of 95dB. The calibrated OPLS-DA model on weakly scattering samples with lipid and water-based absorption features correctly classified 19/20 validation samples. The 1200nm SOCT system can discriminate the lipid-containing weakly scattering samples from water-based weakly scattering samples with good predictive ability.

Calcium Channel Blocker Use and Associated Glaucoma and Related Traits Among UK Biobank Participants

Calcium channel blocker (CCB) use has been associated with an increased risk of glaucoma in exploratory studies. To examine the association of systemic CCB use with glaucoma and related traits among UK Biobank participants. This population-based cross-sectional study included UK Biobank participants with complete data (2006-2010) for analysis of glaucoma status, intraocular pressure (IOP), and optical coherence tomography (OCT)-derived inner retinal layer thicknesses. Data analysis was conducted in January 2023. Calcium channel blocker use was assessed in a baseline touchscreen questionnaire and confirmed during an interview led by a trained nurse. The primary outcome measures included glaucoma status, corneal-compensated IOP, and 2 OCT-derived inner retinal thickness parameters (macular retinal nerve fiber layer [mRNFL] and macular ganglion cell-inner plexiform layer [mGCIPL] thicknesses). We performed logistic regression and linear regression analyses to test for associations with glaucoma status and IOP and OCT-derived inner retinal thickness parameters, respectively. This study included 427 480 adults. Their median age was 58 (IQR, 50-63) years, and more than half (54.1%) were women. There were 33 175 CCB users (7.8%). Participants who had complete data for glaucoma status (n = 427 480), IOP (n = 97 100), and OCT-derived inner retinal layer thicknesses (n = 41 023) were eligible for respective analyses. After adjustment for key sociodemographic, medical, anthropometric, and lifestyle factors, use of CCBs (but not other antihypertensive agents) was associated with greater odds of glaucoma (odds ratio [OR], 1.39 [95% CI, 1.14 to 1.69]; P = .001). Calcium channel blocker use was also associated with thinner mGCIPL (-0.34 μm [95% CI, -0.54 to -0.15 μm]; P = .001) and mRNFL (-0.16 μm [95% CI, -0.30 to -0.02 μm]; P = .03) thicknesses but not IOP (-0.01 mm Hg [95% CI, -0.09 to 0.07 mm Hg]; P = .84). In this study, an adverse association between CCB use and glaucoma was observed, with CCB users having, on average, 39% higher odds of glaucoma. Calcium channel blocker use was also associated with thinner mGCIPL and mRNFL thicknesses, providing a structural basis that supports the association with glaucoma. The lack of association of CCB use with IOP suggests that an IOP-independent mechanism of glaucomatous neurodegeneration may be involved. Although a causal relationship has not been established, CCB replacement or withdrawal may be considered should glaucoma progress despite optimal care.

Discrimination of multiple sclerosis using OCT images from two different centers.

Multiple sclerosis (MS) is one of the most prevalent chronic inflammatory diseases caused by demyelination and axonal damage in the central nervous system. Structural retinal imaging via optical coherence tomography (OCT) shows promise as a noninvasive biomarker for monitoring of MS. There are successful reports regarding the application of Artificial Intelligence (AI) in the analysis of cross-sectional OCTs in ophthalmologic diseases. However, the alteration of thicknesses of various retinal layers in MS is noticeably subtle compared to other ophthalmologic diseases. Therefore, raw cross-sectional OCTs are replaced with multilayer segmented OCTs for discrimination of MS and healthy controls (HCs). To conform to the principles of trustworthy AI, interpretability is provided by visualizing the regional layer contribution to classification performance with the proposed occlusion sensitivity approach. The robustness of the classification is also guaranteed by showing the effectiveness of the algorithm while being tested on the new independent dataset. The most discriminative features from different topologies of the multilayer segmented OCTs are selected by the dimension reduction method. Support vector machine (SVM), random forest (RF), and artificial neural network (ANN) are used for classification. Patient-wise cross-validation (CV) is utilized to evaluate the performance of the algorithm, where the training and test folds contain records from different subjects. The most discriminative topology is determined to square with a size of 40 pixels and the most influential layers are the ganglion cell and inner plexiform layer (GCIPL) and inner nuclear layer (INL). Linear SVM resulted in 88% Accuracy (with standard deviation (std)=0.49 in 10 times of execution to indicate the repeatability), 78% precision (std=1.48), and 63% recall (std=1.35) in the discrimination of MS and HCs using macular multilayer segmented OCTs. The proposed classification algorithm is expected to help neurologists in the early diagnosis of MS. This paper distinguishes itself from other studies by employing two distinct datasets, which enhances the robustness of its findings in comparison with previous studies with lack of external validation. This study aims to circumvent the utilization of deep learning methods due to the limited quantity of the available data and convincingly demonstrates that favorable outcomes can be achieved without relying on deep learning techniques.