Standard Optical Coherence Tomography Research Articles

Sensitivity and specificity of SS-OCT for detecting macular pathologies vs SD-OCT.

To evaluate the sensitivity and specificity of swept-source optical coherence tomography (SS-OCT) biometer compared with the gold standard spectral-domain optical coherence tomography (SD-OCT) for detecting macular pathology in patients with cataract. Eye Centers of Tennessee, Crossville, TN. Prospective, cross-sectional, observational, examiner-masked. The study included 132 participants aged 50 years and older, who underwent precataract surgery work-up. All participants underwent fixation check retinal scans using SS-OCT biometer (IOLMaster 700) as well as full macular scans using Cirrus SD-OCT. 3 independent masked examiners evaluated the scans if they were normal or had a suspected pathology. Different measures of diagnostic accuracy were calculated for 3 examiners. True positive rate (sensitivity) ranged from 71.1% (32/45) to 79.2% (42/53), and false negative rate was between 20.8% (11/53) and 28.9% (13/45) for the 3 examiners. True negative rate (specificity) ranged from 86.8% (59/68) to 94.1% (64/68), and false positive rate was between 5.9 (4/68) and 13.2% (9/68). The fitted receiver operating characteristic area ranged from 0.83 to 0.95. Using retinal SS-OCT biometer scans as a replacement of the dedicated macular SD-OCT for screening or diagnosing macular health would not be appropriate because of its low sensitivity. SS-OCT biometer may potentially fail to identify approximately one-fourth of patients who actually have the disease. Therefore, the final decision on macular health should be based on the gold standard SD-OCT scans. When full macular SD-OCT scans are not accessible, the limited retinal scan information from SS-OCT biometer may still provide useful insights into the macular health.

Diagnostic Utility of Swept-Source OCT-Based Biometry and Fundus Photographs Compared to Spectral Domain OCT in Center-Involving Diabetic Macular Edema

ABSTRACT Purpose This study was aimed to evaluate the agreement between the swept-source optical coherence tomography (SS-OCT)-based biometry, fundus photographs, and their combination, in comparison to the gold standard spectral-domain optical coherence tomography (SD-OCT) for the detection of center-involving diabetic macular edema (CI-DME). Methods We conducted a retrospective cross-sectional study involving 55 subjects (78 eyes) diagnosed with diabetic macular edema (DME) detected clinically and on SD-OCT (Carl Zeiss Meditec AG). Post-mydriatic 45-degree color fundus photograph (Crystal-Vue NFC-700), 1 mm macular scan obtained from SS-OCT-based biometry (IOL-Master 700), and macula cube scan obtained from SD-OCT was used to detect and grade DME into CI-DME and NCI-DME. Results Our findings revealed that SS-OCT-based biometry was noted to have a high sensitivity of 1 (0.94–1.00) and a specificity of 0.63 (0.31–0.89) in detecting CI-DME compared to the gold standard (SD-OCT). When combined with data from fundus photographs, specificity decreased to 0.32 (0.15–0.53). Fundus photographs alone exhibited a low sensitivity of 0.52 (0.38–0.64) and a specificity of 0.45 (0.16–0.76) in CI-DME detection. Conclusion In conclusion, SS-OCT-based biometry can be used as an effective tool for the detection of CI-DME in diabetic patients undergoing cataract surgery and can serve as a screening tool in centers without SD-OCT facilities.

Advances in Photoreceptor and Retinal pigment epithelium Quantifications in intermediate AMD: High-Res versus Standard SPECTRALIS OCT

Purpose: In this study we investigated differences in retinal feature visualization of high-resolution optical coherence tomography (OCT) devices with different axial resolutions in quantifications of retinal pigment epithelium (RPE) and photoreceptors (PR) in intermediate age-related macular degeneration (iAMD). Methods: Patients were imaged with standard SPECTRALIS HRA+OCT and the investigational High-Res OCT device (both by Heidelberg Engineering, Heidelberg, Germany). Drusen, RPE and PR layers were segmented using validated AI-based algorithms followed by manual corrections. Thickness- and drusen maps were computed for all patients. Loss and thickness measurements were compared between devices, drusen vs. non-drusen areas and EDTRS subfields using mixed-effects models. Results: Thirty-three eyes from 28 iAMD patients were included. Normalized PR integrity loss was significantly higher with 4.6% for standard OCT compared to 2.5% on High-Res OCT. The central and parafoveal PR integrity loss was larger than perifoveal loss (p<0.05). PR thickness was increased on High-Res OCT and in non-drusen regions (p<0.001). RPE appeared thicker on standard OCT and above drusen (p<0.01). Conclusion: Our study shows that High-Res OCT is able to identify the condition of investigated layers in iAMD with higher precision. This improved in vivo imaging technology might promote our understanding of the pathophysiology and progression of AMD.

Choroidal neovascularization in children: Etiology, diagnosis, and clinical manifestations

Few studies have analyzed choroidal neovascularization (CNV) in children because of the low incidence of this complication in pediatric ophthalmology. However, given the significant effect on visual acuity and diagnostic difficulties in children, the study of this complication is relevant.
 AIM: This study aimed to analyze the etiological structure and clinical features of CNV in children.
 MATERIAL AND METHODS: From 2014 to 2022, 61 eyes of 54 children (26 girls and 28 boys) had CNV. The patients underwent standard ophthalmologic examination and optical coherence tomography (OCT) and OCT angiography (OCTA) of the macular zone and optic disc using the RS-3000 Advance 2 Tomograph (Nidek, Japan).
 RESULTS: At the time of CNV diagnosis, the children were 5–17 years old, with a mean of 11±3 years. In 30 children (55.6%), CNV was caused by inflammatory lesions of the retina and choroid. Of these cases, 11 occurred during remission, whereas 21 occurred alongside pathologies of the retina, choroid, and optic nerve of noninflammatory genesis (8 of which were associated with Best’s disease). In three children, CNV was considered idiopathic. The development time of postinflammatory CNV ranged from 1 month to 12 years, with an average of 7.3±5 months from disease onset. Type 2 CNV was found in most cases (48 eyes, 78.7%).
 CONCLUSION: CNV is a rare complication of various ocular diseases in children. In our cohort, it was most frequently observed in children with inflammatory lesions of the retina and choroid, even during remission. Patients at risk of CNV must be actively monitored because it occurs in various forms.

Which OCT Measure of the Optic Nerve Head Improves Fastest? Towards Optimizing Early Detection of Resolving Papilledema in Children.

Optical coherence tomography (OCT) has been used to monitor papilledema. This study aims to determine which OCT-derived measures of the optic nerve head (ONH) detect resolving papilledema in children faster than standard OCT measures. Children (≤18years of age) with papilledema who completed optic nerve SD-OCT pretreatment and had evidence of treatment response on one or more follow-up OCTs within 4months were included. Standard (mean circumpapillary retinal nerve fiber layer [cpRNFL] thickness), device-derived (per-quadrant cpRNFL) and custom (ONH height, maximum Bruch's membrane displacement [BMD], ONH volume [ONHV], and BMD volume) OCT measures were calculated. Per-eye generalized estimating equations (GEEs) modelled changes in device-derived and custom measures as a function of mean cpRNFL to identify those measures that resolved faster during early (0-2months) follow-up. Mean cpRNFL coefficients of greater than 1 indicated faster resolving papilledema. We included 52 eyes of 29 children (mean age, 12.8years; 72.4% female). In analysis of early follow-up visits (38 eyes from 22 children), nasal cpRNFL and maximum BMD in each quadrant resolved faster than mean cpRNFL (GEE coefficients range, 1.14-3.37). Inferior cpRNFL, superior, nasal, and inferior ONH heights and ONHV resolved slower than mean cpRNFL (GEE coefficients range, 0.67-0.87). Nasal cpRNFL is a promising device-derived OCT measure for the early detection of resolving papilledema in children compared with mean cpRNFL. Maximum BMD, a custom measure, also shows promise, but its calculation has not yet been incorporated into commercial OCT devices. This study guides the optimal use of OCT in capturing resolving papilledema in children.

Coaxial Bright and Dark Field Optical Coherence Tomography.

To improve the signal collection efficiency of Optical Coherence Tomography (OCT) for biomedical applications. A novel coaxial optical design was implemented, utilizing a wavefront-division beam splitter in the sample arm with a 45-degree rod mirror. This design allowed for the simultaneous collection of bright and dark field signals. The bright field signal was detected within its circular aperture in a manner similar to standard OCT, while the dark field signal passed through an annular-shaped aperture and was collected by the same spectrometer via a fiber array. This new configuration improved the signal collection efficiency by ∼3 dB for typical biological tissues. Dark-field OCT images were found to provide higher resolution, contrast and distinct information compared to standard bright-field OCT. By compounding bright and dark field images, speckle noise was suppressed by ∼ √2 . These advantages were validated using Teflon phantoms, chicken breast ex vivo, and human skin in vivo. This new OCT configuration significantly enhances signal collection efficiency and image quality, offering great potential for improving OCT technology with better depth, contrast, resolution, speckles, and signal-to-noise ratio. We believe that the bright and dark field signals will enable more comprehensive tissue characterization with the angled scattered light. This advancement will greatly promote the OCT technology in various clinical and biomedical research applications.

The predictive value of parameters of optic disk in evaluating the progression of myopia

Aims/Purpose: To analyse the parameters of the optic nerve head (ONH) as markers of the progression of myopia with the usage of optical coherence tomography (OCT).Methods: 72 patients (144 eyes) aged 9–57 years with myopia were investigated. The standard OCT parameters of the ONH, the ovality index (OI), the zone of parapapillary atrophy (PPA), location of the lamina cribrosa (LC) of the sclera and the trunk of the central retinal vessels (CRV) were evaluated. Data was statistically approved.Results: A positive correlation between the axial length (AL) and the optic disc cup area, its horizontal and vertical diameters was found. Whilst the volume and the depth of the optic disc cup increased till the AL reached a certain critical value (26.3 mm) with subsequent reduction. An inverse correlation between the AL and the neuroretinal rim area, volume and rim/disc ratio was revealed. These changes in the ONH can be explained by scleral remodelling during elongation of the eye. Formation of γ‐zone PPA and an increase in the β‐zone PPA was accompanied by the tendency of thinning of the retinal nerve fibre layer (RNFL) in the inferior, nasal‐superior and superior sectors of the ONH. In 27.63% cases tilted optic discs were noted, of which 61.90% were vertically and 38.1% ‐ horizontally tilted. The direction of the tilt was determined by the location of the PPA zone with a tendency to thinning of the RNFL in the same sectors. A positive correlation between the AL of eye and the location of the LC of sclera was found. In 29.17% the superficial location of the LC was determined. In 54.17% elongation was accompanied by displacement of the trunk of the CRV on ONH in the nasal ‐ 71.79%, or in the superior‐nasal direction ‐ 28.21%.Conclusions: The revealed changes of optic disc cup, neuroretinal rim and the parapapillary zones; a superficial displacement of LC of sclera and ‘nasalization’ of the trunk of CRV; a decrease in the OI with growth in the AL; relationships of the PPA zone with a tendency to thinning of the RNFL and direction of the tilt can be useful as OCT markers in interpreting normative data in patients with myopia, predicting its progression, and also in differential diagnosis with glaucomatous optic neuropathy.

Accuracy of swept source biometry device in detecting macular diseases compared with swept source OCT

ObjectiveTo assess the diagnostic accuracy of the IOLMaster 700 foveal scans to detect foveal pathology compared with a standard swept-source optical coherence tomography (SS-OCT) device.ResultsOne hundred seventy eye scans of 95 patients were included in the final analyses. Ninety-nine (58.2%) scans were classified as abnormal by SS-OCT. Mean sensitivity of the biometry device was 67.5% (range: 51–84%) and mean specificity was 69.5% (range: 44–95%). Intra-class correlation coefficients were 0.912 and 0.835, for reader 1 and 2, respectively. Area under the curve for receiver operating curve was 0.726. Foveal scans of the IOLMaster 700 can provide clinically useful information. Clinicians should pay attention to the macular scans when reviewing biometry prior to cataract surgery and standard macular OCT should ideally be supplemented in suspicious cases.

Evaluation of a self-imaging OCT for remote diagnosis and monitoring of retinal diseases

ObjectivesTo evaluate the feasibility and accuracy of a portable, self-imaging optical coherence tomography (OCT) for measuring central subfield thickness (CST) and achieving diagnostic concordance for retinal lesions compared with clinic-based...

A new method for in vivo assessment of corneal transparency using spectral-domain OCT.

Corneal transparency is essential to provide a clear view into and out of the eye, yet clinical means to assess such transparency are extremely limited and usually involve a subjective grading of visible opacities by means of slit-lamp biomicroscopy. Here, we describe an automated algorithm allowing extraction of quantitative corneal transparency parameters with standard clinical spectral-domain optical coherence tomography (SD-OCT). Our algorithm employs a novel pre-processing procedure to standardize SD-OCT image analysis and to numerically correct common instrumental artifacts before extracting mean intensity stromal-depth (z) profiles over a 6-mm-wide corneal area. The z-profiles are analyzed using our previously developed objective method that derives quantitative transparency parameters directly related to the physics of light propagation in tissues. Tissular heterogeneity is quantified by the Birge ratio Br and the photon mean-free path (ls) is determined for homogeneous tissues (i.e., Br~1). SD-OCT images of 83 normal corneas (ages 22-50 years) from a standard SD-OCT device (RTVue-XR Avanti, Optovue Inc.) were processed to establish a normative dataset of transparency values. After confirming stromal homogeneity (Br <10), we measured a median ls of 570 μm (interdecile range: 270-2400 μm). By also considering corneal thicknesses, this may be translated into a median fraction of transmitted (coherent) light Tcoh(stroma) of 51% (interdecile range: 22-83%). Excluding images with central saturation artifact raised our median Tcoh(stroma) to 73% (interdecile range: 34-84%). These transparency values are slightly lower than those previously reported, which we attribute to the detection configuration of SD-OCT with a relatively small and selective acceptance angle. No statistically significant correlation between transparency and age or thickness was found. In conclusion, our algorithm provides robust and quantitative measurements of corneal transparency from standard SD-OCT images with sufficient quality (such as 'Line' and 'CrossLine' B-scan modes without central saturation artifact) and addresses the demand for such an objective means in the clinical setting.

Diffuse-illumination holographic optical coherence tomography.

Holographic optical coherence tomography (OCT) is a powerful imaging technique, but its ability to reveal low-reflectivity features is limited. In this study, we performed holographic OCT by incoherently averaging volumes with changing diffuse illumination of numerical aperture (NA) equal to the detection NA. While the reduction of speckle from singly scattered light is only modest, we discovered that speckle from multiply scattered light can be arbitrarily reduced, resulting in substantial improvements in image quality. This technique also offers the advantage of suppressing noises arising from spatial coherence, and can be implemented with a partially spatially incoherent light source for further mitigation of multiple scattering. Finally, we show that although holographic reconstruction capabilities are increasingly lost with decreasing spatial coherence, they can be retained over an axial range sufficient to standard OCT applications.

Ultra-high-resolution optical coherence tomography for the investigation of thin multilayered pharmaceutical coatings

Optical Coherence Tomography (OCT) has recently gained attention as a promising technology for in-line monitoring of pharmaceutical film-coating processes for (single-layered) tablet coatings and end-point detection with commercial systems. An increasing interest in the investigation of multiparticulate dosage forms with mostly multi-layered coatings below 20 µm final film thickness demands advancement in OCT technology for pharmaceutical imaging. We present an ultra-high-resolution (UHR-) OCT and investigate its performance based on three different multiparticulate dosage forms with different layer structures (one single-layered, two multi-layered) with layer thicknesses in a range from 5 to 50 µm. The achieved system resolution of 2.4 µm (axial) and 3.4 µm (lateral, both in air) enables the assessment of defects, film thickness variability and morphological features within the coating, previously unattainable using OCT. Despite the high transverse resolution, the provided depth of field was found sufficient to reach the core region of all dosage forms under test. We further demonstrate an automated segmentation and evaluation of UHR-OCT images for coating thicknesses, where human experts struggle using today’s standard OCT systems.

Новый подход в прогнозировании функционального результата при лечении пациентов со сквозным макулярным разрывом

Aim. To study the relationship of the characteristics of the preservation of the sensorineural retina and retinal pigment epithelium (RPE) obtained by optical coherence tomography (OCT) with functional recovery in the surgical treatment of full thickness macular hole (FTHM). Materials and methods. This study included 89 patients (95 eyes) with an average age of 67.2 ± 9.6 years, having complete postoperative anatomical closure of the FTMH. All patients underwent standard ophthalmological examination and OCT before surgical treatment. On cross-sectional and en face images, the area and reflexivity of the neurosensory retina tissue at the edges of the gap and the reflexivity of the RPE in the projection of the gap were evaluated. 12 months after surgical treatment, the correlation between the initial indicators of retinal tissue preservation and functional recovery was evaluated. Results. The final best-corrected visual acuity showed a statistically significant correlation with baseline best-corrected visual acuity (r = 0.75, p &lt; 0.001), reflectivity of RPE (r = 0.91, p &lt; 0.001), reflectivity of neurosensory retina (r = – 0.85, p &lt; 0.001), and its area (r = 0.83, p &lt; 0.001). Conclusion. Indicators of retinal tissue preservation, such as the area and reflexivity of the neurosensory retina tissue and the reflexivity of the RPE, correlate with functional recovery after FTMH surgery. Keywords: full-thickness macular hole, optical coherence tomography, optical coherence tomography angiography

Prediction of the Functional Result of Surgery for the Full Thickness of the Macular Hole Based on the Analysis of the Safety of Retinal Tissue

Purpose. To study the relationship between baseline optical coherence tomography (OCT) characteristics of preservation of the neurosensory retina and retinal pigment epithelium (RPE) and functional outcome after full thickness macular hole (FTHM) surgery.Materials and methods. Patients with complete postoperative anatomical closure of the FTMH were included in this prospective interventional study. All patients received a standard ophthalmological examination and OCT before surgical treatment. At baseline the area and reflectivity of the neurosensory retina at the edges of the hole was measured on cross-sectional OCT scans. The reflectivity of RPE was evaluated within the hole on structural en face projections of RPE slab. Six months postoperatively, correlation between baseline OCT characteristics and visual outcome was evaluated.Results. Twenty-nine patients (30 eyes, 23 females and 6 males, average age — 66.2 ± 5.2 years) were included in the study. The final best-corrected visual acuity showed a statistically significant correlation with baseline best-corrected visual acuity (r = 0.75, p &lt; 0.001), reflectivity of RPE (r = 0.81, p &lt; 0.001), reflectivity of neurosensory retina (r = –0.88, p &lt; 0.001), and its area (r = 0.41, p = 0.02).Conclusion. OCT-characteristics of retinal tissue preservation, including the area and reflectivity of the neurosensory retina and reflectivity of the RPE within the hole, correlate with functional recovery after FTMH surgery.

FourierNet: Shape-Preserving Network for Henle's Fiber Layer Segmentation in Optical Coherence Tomography Images.

Henle's fiber layer (HFL), a retinal layer located in the outer retina between the outer nuclear and outer plexiform layers (ONL and OPL, respectively), is composed of uniformly linear photoreceptor axons and Müller cell processes. However, in the standard optical coherence tomography (OCT) imaging, this layer is usually included in the ONL since it is difficult to perceive HFL contours on OCT images. Due to its variable reflectivity under an imaging beam, delineating the HFL contours necessitates directional OCT, which requires additional imaging. This paper addresses this issue by introducing a shape-preserving network, FourierNet, which achieves HFL segmentation in standard OCT scans with the target performance obtained when directional OCT is available. FourierNet is a new cascaded network design that puts forward the idea of benefiting the shape prior of the HFL in the network training. This design proposes to represent the shape prior by extracting Fourier descriptors on the HFL contours and defining an additional regression task of learning these descriptors. FourierNet then formulates HFL segmentation as concurrent learning of regression and classification tasks, in which Fourier descriptors are estimated from an input image to encode the shape prior and used together with the input image to construct the HFL segmentation map. Our experiments on 1470 images of 30 OCT scans of healthy-looking macula reveal that quantifying the HFL shape with Fourier descriptors and concurrently learning them with the main segmentation task leads to significantly better results. These findings indicate the effectiveness of designing a shape-preserving network to facilitate HFL segmentation by reducing the need to perform directional OCT imaging.

AI-based clinical assessment of optic nerve head robustness superseding biomechanical testing

Background/aimsTo use artificial intelligence (AI) to: (1) exploit biomechanical knowledge of the optic nerve head (ONH) from a relatively large population; (2) assess ONH robustness (ie, sensitivity of the ONH...

Relationship of the main indicators of systemic COVID-associated endotheliopathy with the morphofunctional state and hemodynamics of the retina and chorioid in the acute period of the disease

BACKGROUND: Nonspecific angio- and retinopathy is one of the clinical manifestations of a new coronavirus infection. The frequency of occurrence of these changes in people with severe COVID-19 does not exceed 55%. The causes, course and consequences of these microcirculatory disorders of the retina are currently not well understood.&#x0D; AIM: To study and compare of retinal morphometric parameters and systemic endothelial dysfunction markers, as well as the main clinical and laboratory parameters in patients with moderate and severe coronavirus infection during convalescence.&#x0D; MATERIALS AND METHODS: The study involved 44 patients (86 eyes) who had COVID-19 during the previous 3 months, who were divided into 2 groups: with moderate and severe disease. The control group consisted of 18 healthy volunteers (36 eyes). All patients underwent a standard ophthalmological examination and optical coherence tomography, which included an assessment of the choroidal thickness (CT) and measurement of the mean diameter of the peripapillary arteries (MAD) and veins (MVD). During hospitalization, all patients underwent a laboratory study of venous blood parameters, as well as an assessment of the microcirculation of the sublingual plexus by examining the density of the endothelial glycocalyx (PBR) using the GlycoCheck.&#x0D; RESULTS: In patients who underwent COVID-19, there was a significant increase in CT relative to the control group, amounting to 308, 344 and 392 m, respectively. The most pronounced difference was observed between MVD in patients with severe infection and the control group (119.1 m vs. 99.2 m). In patients with moderate and severe COVID-19, MAD and MVD were positively correlated with TC, with r = 0.389 and r = 0.584, respectively. MVD also correlated with the level of leukocytes (r = 0.504), the ESR value (r = 0.656). Correlations between MVD and data characterizing the state of the glycocalyx in the sublingual vascular plexus were revealed: the filling of small capillaries with erythrocytes (r = 0.587), as well as the marginal perfusion value in large capillaries 2025 m (r = 0.479) and PBR (r = 0.479). Only significant differences and correlations are shown (p 0.005).&#x0D; CONCLUSIONS: In patients who underwent moderate and severe COVID-19 during the convalescence period (up to 30 days), an increase in the diameter of peripapillary vessels and TC is observed, proportional to the severity of COVID-19, laboratory markers of systemic inflammation and hypercoagulation (the number of leukocytes, the ESR value, D-dimer and prothrombin), which indicates the inflammatory nature of the changes. The severity of postcovid retinal microangiopathy correlates with indicators detecting a decreasing of the endothelial glycocalyx thickness in the sublingual capillary plexus, which indirectly indicates a connection with systemic endotheliopathy.

Microcrystalline diamond film evaluation by spectroscopic optical coherence tomography

This study has focused on the microcrystalline diamond film (MCD) thickness evaluation. For this purpose, optical coherence tomography (OCT) enhanced by spectroscopic analysis has been used as a method of choice. The average thickness of the tested layer was about 1.5 µm, which is below the standard 2-point OCT resolution. In this case, the usefulness of the spectroscopic analysis was confirmed for the evaluation of the thickness changes in the submicrometer range. Full Text: PDF ReferencesM.D. Drory, J.W. Hutchinson, "Diamond Coating of Titanium Alloys", Science, 263 (1994). CrossRef J. Wang, J. Zhou, H.Y. Long, Y.N. Xie, X.W. Zhang, H. Luo, Z.J. Deng, Q. Wei, Z.M. Yu, J. Zhang, Z.G. Tang, "Tribological, anti-corrosive properties and biocompatibility of the micro- and nano-crystalline diamond coated Ti6Al4V", Surf. Coat. Technol., 258 (2014). CrossRef P.A. Nistor, P.W. May, F. Tamagnini, A.D. Randall, M.A. Caldwell, "Long-term culture of pluripotent stem-cell-derived human neurons on diamond – A substrate for neurodegeneration research and therapy", Biomaterials, 61 (2015). CrossRef C.A. Love, R.B. Cook, T.J. Harvey, P.A. Dearnley, R.J.K. Wood, "Diamond like carbon coatings for potential application in biological implants—a review", Tribol. Int., 63 (2013). CrossRef P. Strąkowska, R. Beutner, M. Gnyba, A. Zielinski, D. Scharnweber, "Electrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films — Coating characterization and first cell biological results", Materials Science and Engineering: C, 59 (2016). CrossRef T.S. Ho, P. Yeh, C.C. Tsai, K.Y. Hsu, S.L. Huang., "Spectroscopic measurement of absorptive thin films by Spectral-Domain Optical Coherence Tomography", Opt. Express 22, 5 (2014). CrossRef N. Bosschaart, T.G. van Leeuwen, M.C.G. Aalders, D.J. Faber, "Quantitative comparison of analysis methods for spectroscopic optical coherence tomography", Biomedical Opt. Express 4, 11 (2013). CrossRef F.E Robles, C. Wilson, G. Grant, A. Wax, "Molecular imaging true-colour spectroscopic optical coherence tomography", Nat. Photonics 5, 12 (2011). CrossRef A.F. Fercher, W. Drexler, C.K. Hitzenberger, T. Lasser, "Optical coherence tomography - principles and applications", Rep. Prog. Phys. 66, 239 (2003). CrossRef A.M. Kamińska, M.R. Strąkowski, J. Pluciński, "Spectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurements", Sensors 20, 19, (2020). CrossRef M. Kraszewski, M. Strąkowski, J. Pluciński, B.B. Kosmowski, "Spectral measurement of birefringence using particle swarm optimization analysis", Appl. Opt. 54, 1 (2015). CrossRef

Analysis of the signal measured in spectral-domain optical coherence tomography based on nonlinear interferometers

We analyze and compare the output signals obtained in three different configurations of optical coherence tomography (OCT). After appropriate processing, these signals are used to retrieve an image of the sample under investigation. One of the configurations considered is the common choice in most OCT applications and is based on the use of a Michelson interferometer. For brevity, here we refer to it as standard OCT. The other two configurations are two types of optical coherence tomography based on the use of so-called nonlinear interferometers, interferometers that contain optical parametric amplifiers inside. The goal is to highlight the differences and similarities between the output signals measured in standard OCT and in these two OCT schemes, with the aim of evaluating if retrieval of information about the sample can be better done in one case over the others. We consider schemes where the optical sectioning of the sample is obtained by measuring the output signal spectrum (spectral or Fourier-domain OCT), since it shows better performance in terms of speed and sensitivity than the counterpart time-domain OCT.

WIDEFIELD SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FINDINGS IN WAGNER SYNDROME.

To describe novel clinical and angiographic findings in Wagner syndrome. A retrospective case series of three related patients with Wagner syndrome. Patients underwent standard optical coherence tomography (OCT), B-scan ultrasonography, and fluorescein angiography in addition to wide field swept-source OCT angiography (WF SS-OCTA) (PLEX Elite 9000, Carl Zeiss Meditec Inc). Patients underwent genetic testing for a panel of hereditary vitreoretinopathies. Three related patients with Wagner syndrome were identified. All were found to have prominent vitreous strands, abnormal vitreoretinal adhesions, peripheral retinal holes, and varying degrees of myopia. A mid-peripheral tractional ridge was identified in all six eyes. All patients were positive for a known pathologic intron variant in the VCAN gene (4004-5T-A). Wide field swept-source OCT angiography (12 mm × 12 mm) was performed in two patients and demonstrated perivascular capillary loss in the superficial capillary plexus along the arcades bilaterally. One patient demonstrated associated retinal atrophy within the area of capillary loss. The capillary loss extended beyond the margin of retinal atrophy. The unusual finding of a mid-peripheral tractional ridge of the retina associated with myopia led to a genetic diagnosis of Wagner syndrome. Widefield swept-source OCT angiography demonstrated a novel feature of perivascular loss of the superficial retinal capillary plexus. This result suggests that vitreous traction may cause localized microvasculature dysfunction and subsequent retinal atrophy in Wagner syndrome. This is the first known evaluation of Wagner syndrome using OCT angiography.