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AIM: To compare the differences of choroidal neovascularization (CNV) measurements between swept-source and spectral-domain optical coherence tomography angiography (SS-OCTA and SD-OCTA) in neovascular age-related macular degeneration (nAMD) and the imaging reliability of the two devices. METHODS: Prospective comparative study. SS-OCTA and SD-OCTA were used to scan the same eye with the modes of 3×3 and 6×6 mm2 centered on the neovascularization. Only qualified images were chosen and the border of CNV was manually delineated by two graders independently. The area of CNV (ACNV), vascular perfusion density (PD), and vessel length density (VLD) within the delineation were calculated using Image J. The differences of CNV measurements between the two OCTA devices were compared using Bland-Altman analysis. The agreement between the two graders on the measurements of each device was compared using the intraclass correlation coefficient (ICC). RESULTS: A total of 18 patients (22 eyes) with nAMD were included. The measurements of ACNV, PD, and VLD were 7.247±4.586 and 4.901±3.741 mm2, 43.202±9.636 and 34.904±10.489, 6.339±1.228 and 5.908±1.741 mm-1 for SS-OCTA and SD-OCTA, respectively. The differences between the two devices were 2.346±3.030 mm2 (Z= -3.782, P

Medical imaging is the mainstay of clinical diagnosis and management. Optical coherence tomography (OCT) is a non-invasive imaging technology that has revolutionized the field of ophthalmology. Since its introduction, OCT has undergone significant improvements in image quality, speed, and resolution, making it an essential diagnostic tool for various ocular pathologies. OCT has not only improved the diagnosis and management of ocular diseases but has also found applications in other fields of medicine. In this manuscript, we provide a brief overview of the history of OCT, its current uses and diagnostic capabilities to assess the posterior segment of the eye, and the evolution of this technology from time-domain (TD) to spectral-domain (SD) and swept-source (SS). This brief review will also discuss the limitations, advantages, disadvantages, and future perspectives of this technology in the field of ophthalmology. [ABSTRACT FROM AUTHOR]

In the context of exponential demographic growth, the imbalance between human resources and public health problems impels us to envision other solutions to the difficulties faced in the diagnosis, prevention, and large-scale management of the most common diseases. Cardiovascular diseases represent the leading cause of morbidity and mortality worldwide. A large-scale screening program would make it possible to promptly identify patients with high cardiovascular risk in order to manage them adequately. Optical coherence tomography angiography (OCT-A), as a window into the state of the cardiovascular system, is a rapid, reliable, and reproducible imaging examination that enables the prompt identification of at-risk patients through the use of automated classification models. One challenge that limits the development of computer-aided diagnostic programs is the small number of open-source OCT-A acquisitions available. To facilitate the development of such models, we have assembled a set of images of the retinal microvascular system from 499 patients. It consists of 814 angiocubes as well as 2005 en face images. Angiocubes were captured with a swept-source OCT-A device of patients with varying overall cardiovascular risk. To the best of our knowledge, our dataset, Retinal oct-Angiography and cardiovascular STAtus (RASTA), is the only publicly available dataset comprising such a variety of images from healthy and at-risk patients. This dataset will enable the development of generalizable models for screening cardiovascular diseases from OCT-A retinal images. Dataset:  https://rasta.u-bourgogne.fr/ Dataset License: CC-BY 4.0 [ABSTRACT FROM AUTHOR]

Abstract Background To perform a quantitative analysis of retinal microvasculature in patients with early-stage diabetic retinopathy (DR) using wide-field swept-source optical coherence tomography angiography (SS-OCTA). Methods One hundred nineteen eyes of 119 patents (67 eyes with no DR and 52 eyes with mild-moderate nonproliferative diabetic retinopathy (NPDR)) were enrolled in this observational and cross-sectional cohort study, and an age-matched group consisting of 39 eyes of 39 non-diabetic subjects were set as the control. Each participant underwent a full ophthalmic examination, including wide-field SS-OCTA imaging. On OCTA scans (12 mm * 12 mm), the mean perfusion area (PA) and vessel density (VD) were independently measured in all 16 Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. Linear regression analyses were conducted to evaluate the influences of PA. Results In the central ring, there were no significant differences in the average PA and VD among the groups. In the 3 mm radius, the PA and VD of the no DR and mild-moderate NPDR were significantly decreased compared with the control group in superior and inferior quadrants. In the wide-field scans (9 and 12 mm radius), there was no significant difference in average PA and VD between the groups in each sectors (p > 0.05). Regression analysis found that the effect of VD on PA was statistically different (b = 1.311, p

AIM: To investigate the correlation between postoperative lens decentration and tilt and visual quality in eyes implanted with aspherical intraocular lens(IOL)by using a new anterior segment swept-source optical coherence tomography(OCT)CASIA2.METHODS: An observational study. A total of 90 eyes of 62 participants who underwent age-related cataract surgery at 1mo were included. Using CASIA2 by an experienced examiner, IOL tilt and decentration were obtained three consecutive times after mydriasis and the vector mean values were calculated. Double-pass optical quality analysis system(OQAS)and wavefront aberration instrument KR-1W were used for the visual quality measurements, including the total high-order aberration(tHOA), spherical aberration(SA), Coma, objective scatter index(OSI), modulation transfer function cut off frequency(MTF cut off)and Strehl ratio(SR)at 4 and 6mm pupil diameter.RESULTS: IOL decentration was positively correlated with SA(r=0.347, P=0.001)and OSI(r=0.343, P=0.002)at 4mm pupil diameter, and it was negatively correlated with MTF cut off(r=-0.244, P=0.032). There was no significant correlation between IOL decentration and tHOA, Coma and SR. IOL tilt was negatively correlated with MTF cut off(r=0.-345, P=0.002)and SR(r=-0.256, P=0.023)at 4mm pupil diameter, but it was not correlated with tHOA, SA, Coma and OSI. There were no significant correlations between the IOL decentration and tilt and tHOA, SA, Coma, MTF cut off and SR at 6mm pupil diameter.CONCLUSION: After aspherical IOL implantation in age-related cataract patients, IOL decentration was weakly correlated with SA at 4mm pupil diameter, while decentration and tilt were not significantly correlated with other higher-order aberrations. The decentration and tilt were weakly correlated with OSI value and MTF cut off value of the visual quality parameters. The results suggest that clinicians should pay more attention to higher-order aberrations and visual quality during precise cataract surgery.

The choroid is the main part of the uvea, the vascular layer of the eye that lies between the retina and the sclera. The high vascular component of the choroid makes this structure susceptible to inflammation in multisystemic diseases, as well as the most common site of metastasis in the eye. Therefore, the choroid is involved in many pathological conditions, from uveitis to intraocular tumors. Differentiating between inflammatory and neoplastic lesions deforming the choroidal profile can sometimes be challenging. In addition, scleral disorders can also deform the choroidal profile. Choroidal imaging includes ophthalmic ultrasonography, indocyanine green angiography, and optical coherence tomography (OCT). Recent advances in choroidal imaging techniques, such as enhanced depth imaging optical coherence tomography (EDI-OCT) and swept-source optical coherence tomography (SS-OCT), have facilitated an in-depth analysis of the choroid. The purpose of this review article is to report on and highlight the most common OCT findings to help in the differential diagnosis between inflammatory and neoplastic lesions deforming the choroidal profile. [ABSTRACT FROM AUTHOR]

AIM: To perform a quantitative analysis of the peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness changes in patients with early stage of diabetic retinopathy (DR). METHODS: In this case-control study, swept-source optical coherence tomography angiography (SS-OCTA) imaging was used to examine diabetic and age-matched healthy subjects. The optic disc HD 6×6 mm2 blood flow imaging scan mode was selected. Automatic software was used to measure the peripapillary VD, capillary vessel density (CVD), and RNLF in an optic nerve head (ONH) filed based on the Garway-Heath map. In addition, the correlation between peripapillary VD, CVD, and RNFL was further investigated. RESULTS: The cohort consisted of 32 healthy individuals and 72 patients with diabetes (34 eyes with no DR and 38 eyes with mild-moderate NPDR). Peripapillary VD decreased in the mild-moderate NPDR group compared to the control group in most regions (P

Medical imaging is the mainstay of clinical diagnosis and management. Optical coherence tomography (OCT) is a non-invasive imaging technology that has revolutionized the field of ophthalmology. Since its introduction, OCT has undergone significant improvements in image quality, speed, and resolution, making it an essential diagnostic tool for various ocular pathologies. OCT has not only improved the diagnosis and management of ocular diseases but has also found applications in other fields of medicine. In this manuscript, we provide a brief overview of the history of OCT, its current uses and diagnostic capabilities to assess the posterior segment of the eye, and the evolution of this technology from time-domain (TD) to spectral-domain (SD) and swept-source (SS). This brief review will also discuss the limitations, advantages, disadvantages, and future perspectives of this technology in the field of ophthalmology.

Background: To perform a quantitative analysis of retinal microvasculature in patients with early-stage diabetic retinopathy (DR) using wide-field swept-source optical coherence tomography angiography (SS-OCTA). Methods: One hundred nineteen eyes of 119 patents (67 eyes with no DR and 52 eyes with mild-moderate nonproliferative diabetic retinopathy (NPDR)) were enrolled in this observational and cross-sectional cohort study, and an age-matched group consisting of 39 eyes of 39 non-diabetic subjects were set as the control. Each participant underwent a full ophthalmic examination, including wide-field SS-OCTA imaging. On OCTA scans (12 mm * 12 mm), the mean perfusion area (PA) and vessel density (VD) were independently measured in all 16 Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. Linear regression analyses were conducted to evaluate the influences of PA. Results: In the central ring, there were no significant differences in the average PA and VD among the groups. In the 3 mm radius, the PA and VD of the no DR and mild-moderate NPDR were significantly decreased compared with the control group in superior and inferior quadrants. In the wide-field scans (9 and 12 mm radius), there was no significant difference in average PA and VD between the groups in each sectors (p > 0.05). Regression analysis found that the effect of VD on PA was statistically different (b = 1.311, p < 0.001). Conclusion: Wide-field OCTA imaging is useful for evaluating peripheral capillary perfusion in eyes with early-stage DR. Decrease in PA and VD was greater in the S3 and I3 sectors, and reductions in PA and VD were uneven in wide-filed sectors (9 and 12 mm radius). [ABSTRACT FROM AUTHOR]

OBJECTIVE: In order to solve the problem of image real-time processing and correction for high-speed endoscopic sweptsource optical coherence tomography (SS-OCT), we highly optimize a computer-unified device architecture-based platform and use a field-programmable gate array to summarize the application experience. MATERIALS AND METHODS: We use the Half-Sync/Half-Asyn mode to optimize memory in order to build a high-throughput data thread pool for CPU. We use asynchronous streaming architecture to multiplex multiple threads at high speed to accelerate data processing. At the same time, we design a rotary scanning position information encoding feedback module to suppress image drift, which can realize 25ns logic-timing sequence synchronization control through FPGA 40MHz clock. RESULTS: The maximum complete attainable axial-scan-processing rate (including memory transfer and display of B-scan frames) is 3.52 MHz for a 16-bit pixel depth and A-scans/s of 1024 pixels. To our knowledge, this is the fastest processing rate reported to date with a single-chip graphical processing unit for SS-OCT. Finally, the established high-speed SS-OCT is used to image mouse esophagus and human fingers, and the output images are stable. When the image size is 1024 × 1024 pixels, the real-time imaging rate is 200 frames per second. CONCLUSIONS: This paper develops a real-time image processing and reconstruction technology suitable for high-throughput SS-OCT systems, which can have high-density operation and efficient parallelism, while suppressing highspeed image drift. It lays the foundation for the non-destructive, in vivo, non-staining, fast and convenient early tumor diagnosis of high-speed endoscopic SS-OCT. [ABSTRACT FROM AUTHOR]

Deep optic disc drusen (ODD) are located below Bruch's membrane opening (BMO) and may go undetected due to the challenges in imaging them. The purpose of this study is a head-to-head comparison of currently widely used imaging technologies: swept-source optical coherence tomography (SS-OCT; DRI OCT-1 Triton, Topcon) and enhanced depth imaging spectral-domain optical coherence tomography (EDI SD-OCT; Spectralis OCT, Heidelberg Engineering) for the detection of deep ODD and associated imaging features. The eyes included in this study had undergone high-resolution imaging via both EDI SD-OCT and SS-OCT volume scans, which showed at least one deep ODD or a hyperreflective line (HL). Grading was performed by three graders in a masked fashion. The study findings are based on 46 B-scan stacks of 23 eyes including a total of 7981 scans. For scan images with ODD located above or below the level of BMO, no significant difference was found between the two modalities compared in this study. However, for HLs and other features, EDI SD-OCT scan images had better visualization and less artifacts. Although SS-OCT offers deep tissue visualization, it did not appear to offer any advantage in ODD detection over a dense volume scan via EDI SD-OCT with B-scan averaging. [ABSTRACT FROM AUTHOR]

Aim: To compare the differences of choroidal neovascularization (CNV) measurements between swept-source and spectral-domain optical coherence tomography angiography (SS-OCTA and SD-OCTA) in neovascular age-related macular degeneration (nAMD) and the imaging reliability of the two devices., Methods: Prospective comparative study. SS-OCTA and SD-OCTA were used to scan the same eye with the modes of 3×3 and 6×6 mm 2 centered on the neovascularization. Only qualified images were chosen and the border of CNV was manually delineated by two graders independently. The area of CNV (ACNV), vascular perfusion density (PD), and vessel length density (VLD) within the delineation were calculated using Image J. The differences of CNV measurements between the two OCTA devices were compared using Bland-Altman analysis. The agreement between the two graders on the measurements of each device was compared using the intraclass correlation coefficient (ICC)., Results: A total of 18 patients (22 eyes) with nAMD were included. The measurements of ACNV, PD, and VLD were 7.247±4.586 and 4.901±3.741 mm 2 , 43.202±9.636 and 34.904±10.489, 6.339±1.228 and 5.908±1.741 mm -1 for SS-OCTA and SD-OCTA, respectively. The differences between the two devices were 2.346±3.030 mm 2 ( Z =-3.782, P <0.0001), 8.298±14.160 ( Z =-2.419, P =0.016), and 0.431±2.114 mm -1 ( Z =-0.828, P =0.408) for ACNV, PD and VLD, respectively. The ICC between two graders were 0.893 ( P <0.001), 0.902 ( P <0.001), 0.885 ( P <0.001) for ACNV, PD, VLD in SS-OCTA, and 0.971 ( P <0.001), 0.976 ( P <0.001), 0.973 ( P <0.001) in SD-OCTA, respectively., Conclusion: Both OCTA devices have high imaging reliability. Compared with SD-OCTA, SS-OCTA has a larger ACNV measurements, but doesn't show better resolution of internal vessels of CNV and well signal strength., Competing Interests: Conflicts of Interest: Ma JX, None; Zhang ZY, None; Di R, None; Yang JJ, None; Tian SW, None; Qin YZ, None; Zhang WH, None; Lei JQ, None; Liu QP, None; Li JM, None., (International Journal of Ophthalmology Press.)

In the context of exponential demographic growth, the imbalance between human resources and public health problems impels us to envision other solutions to the difficulties faced in the diagnosis, prevention, and large-scale management of the most common diseases. Cardiovascular diseases represent the leading cause of morbidity and mortality worldwide. A large-scale screening program would make it possible to promptly identify patients with high cardiovascular risk in order to manage them adequately. Optical coherence tomography angiography (OCT-A), as a window into the state of the cardiovascular system, is a rapid, reliable, and reproducible imaging examination that enables the prompt identification of at-risk patients through the use of automated classification models. One challenge that limits the development of computer-aided diagnostic programs is the small number of open-source OCT-A acquisitions available. To facilitate the development of such models, we have assembled a set of images of the retinal microvascular system from 499 patients. It consists of 814 angiocubes as well as 2005 en face images. Angiocubes were captured with a swept-source OCT-A device of patients with varying overall cardiovascular risk. To the best of our knowledge, our dataset, Retinal oct-Angiography and cardiovascular STAtus (RASTA), is the only publicly available dataset comprising such a variety of images from healthy and at-risk patients. This dataset will enable the development of generalizable models for screening cardiovascular diseases from OCT-A retinal images.

Purpose: To assess the acquisition rate and agreement of axial length (AL) measurements with the OA-2000, Anterion, and IOLMaster 500 in cataractous patients. Methods: In total, 298 eyes of 191 cataractous patients were enrolled and scanned with the three devices in random order. The success rate of AL measurements per device was calculated and a chi-square test was utilized to identify the differences in acquisition rate between the three devices. Logistic regression analysis was applied to evaluate the association of different cataract types and severity with the AL measurement acquisition rate. Bland–Altman plots were mapped to appraise the agreement of AL values. Results: AL measurements were successfully achieved in 288 eyes (96.64%) with the OA-2000, in 282 eyes (94.30%) with the Anteiron, and in 246 eyes (82.55%) with the IOLMaster 500. Significant differences in the acquisition rate were found between either of the SS-OCT devices and IOLMaster 500 by chi-square analysis (P < 0.001). No significant difference was noted between OA-2000 and Anterion. Increasing severity of posterior subcapsular cataract was associated with a higher failure rate with the IOLMaster 500. Bland–Altman analysis identified good agreement between the three biometers with narrow 95% limits of agreement. Conclusions: The OA-2000 and Anterion showed similarly higher acquisition rate of AL measurements than IOLMaster 500 in cataractous patients. Good agreement for AL values was found between the three biometers in cataractous patients. [ABSTRACT FROM AUTHOR]

Purpose: In the event that any ocular parameter involved in the calculation of intraocular lens power could not be properly measured in one eye, it is important to know whether clinically relevant differences between both eyes can be expected. The aim of this work is to evaluate the symmetry of interocular biometric parameters. Methods: This was a prospective, cross-sectional study involving 4090 subjects. Patients underwent consecutive swept-source optical biometry performed with an IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany). The biometric parameters that were evaluated were: axial length (AL), mean anterior curvature (Rm), anterior chamber depth (ACD), crystalline lens thickness (LT), central corneal thickness (CCT) and white-to-white (WTW). The Chang–Waring chord distance (CWC-D) and the Chang–Waring chord angle (CWC-A) were also evaluated. Results: There is an excellent correlation between both eyes for almost all the biometric parameters under study, with the exception of the CWC. Agreement for AL was better for eyes shorter than 24 mm. The linearity of the OD-vs-OS relationship can be correctly assumed for all parameters (Cusum test: p > 0.05 in all cases). Conclusion: There are no clinically significant interocular differences for the biometric parameters under study, although for all of them, except the LT, statistically significant differences did arise. In the case of AL, moderate differences can be expected in eyes larger than 24 mm. [ABSTRACT FROM AUTHOR]

Abstract Background To investigate swept-source optical coherence tomography angiography (SS-OCTA) for deep choroid visualization and choroidal vascular density (CVD) measurement. Methods Healthy subjects and central serous chorioretinopathy (CSC) patients were recruited for macular SS-OCTA scans. We evaluated OCTA images at various depths to determine an optimal depth for visualizing choroidal vasculatures. We measured CVD with binarized OCTA images at the optimal depth. In healthy subjects, CVD was studied for its correlation with age, axial length (AL), and subfoveal choroidal thickness (SCT). In CSC eyes, CVD was compared with matched controls. Results Ninety-one healthy eyes and 22 CSC eyes were included. SS-OCTA could display deep choroidal vasculatures as dark signals, with 100 μm beneath BM as the optimal depth. In healthy subjects, the CVD at 100 μm beneath BM (56.5 ± 10.9%) was significantly correlated with SCT (P = 0.004) but not with age (P = 0.49) or AL (P = 0.72). In CSC eyes, the CVD at 100 μm beneath BM (62.3 ± 6.6%) was larger than that in 22 matched controls (54.1 ± 8.0%) (P = 0.001). The difference remained statistically significant after adjusting for SCT (P = 0.02). Conclusions SS-OCTA can be used for visualizing deep choroidal vasculatures. CVD measured by OCTA at 100 μm beneath BM is a useful parameter for quantifying choroidal vascular status.

Purpose: To develop an objective intraocular inflammation composite score. Methods: Cross‐sectional study. Non‐invasive image acquisition and processing were conducted from April 2017 to April 2019. Inflammation‐grade stratified eyes from patients with active, inactive uveitis and healthy controls were recruited. After clinical assessment, four anterior and posterior segment image acquisition protocols per eye, using swept‐source optical coherence tomography (SS‐OCT), were performed at inclusion. Eight imaging biomarkers in three domains: anterior, intermediate and posterior were studied. They were ranked and selected by discriminatory power and correlation with clinical scores. A final SS‐OCT‐derived composite uveitis activity score (SS‐UAS) was developed through multiple linear regression. Results: We studied 224 eyes with uveitis (165 active and 59 inactive) from 165 patients (mean age 46.6 SD 15.5 years; 55.3% women) and 38 eyes from 19 healthy controls (mean age 43.6 SD 17.1; 47% women). The selected SS‐OCT‐derived biomarkers to build the final score were anterior chamber hyper‐reflective dots (anterior), high‐definition relative vitreous intensity (intermediate) and the averaged thickened retinal index (posterior). Swept‐source (SS)‐UAS was highly discriminant between active and inactive, and between active and healthy eyes (means 2.06 SD 1.86, 0.93 SD 0.44, and 0.96 SD 0.38, respectively, both p ‐, Mann–Whitney U). Construct validity (Cronbach's alpha = 0.7), internal consistency, criterion validity and reliability (concordance correlation coefficient intra‐rater = 0.99, 95% CI: 0.98–0.99; inter‐rater = 0.98, 95% CI: 0.96–0.99) were favourable. Conclusions: Global intraocular inflammation can potentially be staged and scored objectively, continuously, consistently and in a valid manner through the combined processing of SS‐OCT scans. [ABSTRACT FROM AUTHOR]

Deep optic disc drusen (ODD) are located below Bruch’s membrane opening (BMO) and may go undetected due to the challenges in imaging them. The purpose of this study is a head-to-head comparison of currently widely used imaging technologies: swept-source optical coherence tomography (SS-OCT; DRI OCT-1 Triton, Topcon) and enhanced depth imaging spectral-domain optical coherence tomography (EDI SD-OCT; Spectralis OCT, Heidelberg Engineering) for the detection of deep ODD and associated imaging features. The eyes included in this study had undergone high-resolution imaging via both EDI SD-OCT and SS-OCT volume scans, which showed at least one deep ODD or a hyperreflective line (HL). Grading was performed by three graders in a masked fashion. The study findings are based on 46 B-scan stacks of 23 eyes including a total of 7981 scans. For scan images with ODD located above or below the level of BMO, no significant difference was found between the two modalities compared in this study. However, for HLs and other features, EDI SD-OCT scan images had better visualization and less artifacts. Although SS-OCT offers deep tissue visualization, it did not appear to offer any advantage in ODD detection over a dense volume scan via EDI SD-OCT with B-scan averaging.

Abstract Introduction We compared peripapillary retinal nerve fiber layer and macular thickness measurements in patients with mild cognitive impairment (MCI) and control subjects using swept‐source optical coherence tomography (SS‐OCT). We also assessed the relationship between SS‐OCT measurements and the severity of cognitive impairment. Methods Peripapillary retinal nerve fiber layer and macular thickness were measured in 23 patients and 24 control subjects using SS‐OCT. Cognitive status was assessed using the Mini‐Mental State Examination, the Montreal Cognitive Assessment, and the Pfeffer Questionnaire. Results Most inner retinal layer thickness parameters were significantly smaller in patients with MCI, especially macular ganglion cell complex thickness measurements. Mini‐Mental State Examination and Montreal Cognitive Assessment findings were significantly correlated with most macular thickness parameters. Discussion The SS‐OCT–measured inner retinal layers of patients with MCI displayed thinning, especially in the central macular area. SS‐OCT technology can provide useful information on ocular involvement patterns and holds promise as an ocular biomarker in this patient population.

A 48-year-old female presented with complaints of recent onset diminution of vision of the left eye (OS) for the past 2 months. She was highly myopic and was using glasses for the past 30 years. Ocular examination revealed presence of a myopic fundus with high axial lengths in both the eyes. Fundus examination of the OS revealed a myopic tessellated fundus with prominent choroidal vessels and a blunted foveal reflex. There was a small pale whitish lesion just superior to the foveal center. Optical coherence tomography (OCT) scans (both horizontal and vertical) confirmed presence of dome-shaped maculopathy. There was subretinal fluid in the OS. A vertical OCT scan also revealed a subretinal hyperreflective material, which was confirmed to be due to a small mixed type 1 and type 2 choroidal neovascularization (CNV) on swept-source (SS) OCT angiography in the OS. The patient was given intravitreal injection of ranibizumab (0.5 mg/0.05 mL) in the OS. At 1-month follow-up, the subretinal fluid completely resolved. The CNV lesion regressed significantly on SS-OCT angiography. The best-corrected visual acuity improved from 20/80 to 20/20 in the OS, which was maintained at 3 months of follow-up.

Purpose: To compare the lesion sizes of macular neovascularization (MNV) imaged with spectral‐domain (SD) and swept‐source (SS) optical coherence tomography angiography (OCTA) as well as indocyanine green angiography (ICGA). Methods: In this prospective, observational case series, patients showing a secured diagnosis of MNV on ICGA or Fluorescein Angiography, were imaged by SD‐OCTA and SS‐OCTA on the same day. Lesion size was measured on 3 × 3‐mm2 and 6 × 6‐mm2 scans using the Maestro 2 SD‐OCTA (Topcon Corporation, Tokyo Japan) and the Triton SS‐OCTA device (Topcon Corporation, Tokyo Japan) and compared to ICGA (Spectralis HRA, Heidelberg, Germany). Results: Twenty eyes from 20 patients (11 females, 55%) were enrolled. The neovascularization area measured on 6 × 6‐mm2 SD‐OCTA was lower compared to that outlined on SS‐OCTA, however, not reaching statistical significance (p = 0.094). Regarding 3 × 3‐mm2 measurements, the median lesion sizes between the two OCTA devices were comparable (p = 0.492). Indocyanine green angiography depicted a larger lesion area than both OCTA devices, however, not reaching statistical significance. Conclusion: SD‐OCTA tends to show smaller areas of MNV extension than SS‐OCTA regarding 6 × 6 mm2 scans. The lesion size of MNV can be very well compared between the different devices, emphasizing the use of OCTA for monitoring neovascular area. Lesion measurements on SS‐OCTA correlate better with ICGA than SD‐OCTA. [ABSTRACT FROM AUTHOR]

Chromatic confocal microscopy (CCM) has been intensively developed because it can exhibit effective focal position scanning based on the axial chromatic aberration of broadband light reflected from a target. To improve the imaging speed of three-dimensional (3D) surface profiling, we have proposed the novel concept of swept-source-based CCM (SS-CCM) and investigated the usefulness of the corresponding imaging system. Compared to conventional CCM based on a broadband light source and a spectrometer, a swept-source in the proposed SS-CCM generates light with a narrower linewidth for higher intensity, and a single photodetector employed in the system exhibits a fast and sensitive response by immediately obtaining spectrally encoded depth from a chromatic dispersive lens array. Results of the experiments conducted to test the proposed SS-CCM system indicate that the system exhibits an axial chromatic focal distance range of approximately 360 μ m for the 770–820 nm swept wavelength range. Moreover, high-speed surface profiling images of a cover glass and coin were successfully obtained with a short measurement time of 5 ms at a single position. [ABSTRACT FROM AUTHOR]

Purpose: Previous studies on the association between macular vessel density (VD) and diabetic retinopathy had conflicting conclusions. This study assessed the alterations of macular VD, as well as other factors, in diabetic patients using swept-source optical coherence tomography angiography (SS-OCTA) in a large-scale sample from Chinese communities. Methods: Patients with type 2 diabetes without history of ocular treatment were recruited from 2017 to 2018. The average and quadrant parafoveal vessel density (PVD) were obtained with a commercial SS-OCTA device (Triton, Topcon, Japan). The univariate and multivariate linear regression was used to analyse the correlation of PVD with diabetic retinopathy (DR), diabetic macular edema (DME), HbA1c, and other factors. Results: A total of 919 patients were included in the final statistical analysis. After adjusting for other confounding factors, the DR patients had significantly lower average PVD (β = − 1.062, 95% CI = − 1.424 to − 0.699, P < 0.001) in comparison with those without DR. In addition, the patients with mild DR or vision-threatening diabetic retinopathy (VTDR) also had significantly lower PVD (P < 0.001 for mild DR, and P = 0.008 for VTDR) compared with those without DR. Age and HbA1c were also significantly related to PVD measurements, as shown by multivariable linear regression. Participants with DME had a significantly lower average PVD and temporal PVD than those without DME (P < 0.05). Conclusions: Reduced PVD was independently associated with more severe DR, older age, higher HbA1c level, and the presence of DME. These findings suggested that macular vessel alterations in DR warrant further evaluation in the longitudinal studies. [ABSTRACT FROM AUTHOR]

The dispersion-tuned swept laser (DTSL) is a wavelength-swept source, which can achieve fast sweep without using any mechanical tunable filter. Such fast wavelength-swept sources are highly suitable for swept-source optical coherent tomography (SS-OCT). DTSL-based SS-OCT (DTSL-OCT) can deliver a very fast imaging speed, however, it suffers from a limited imaging depth due to the its limited coherence length. In this article, digital coherent detection techniques are applied to the DTSL-OCT to improve the imaging depth and axial resolution. We show that the two phase-uncertainty-induced impairments, namely, the image degeneracy and the wavelength-sweep-nonlinearity, can be compensated by signal processing on the complex interferometric signals acquired using digital coherent detector. Removal of the mirror images resulting from complex conjugate artifact enables the full-range measurement, and the wavelength-sweep-nonlinearity compensation improves the axial resolution. We experimentally demonstrated that the OPD corresponding to a 6 dB-drop in the point-spread function (PSF) peak level can be improved from 1.4 mm to 7.2 mm. [ABSTRACT FROM AUTHOR]

Background: To investigate swept-source optical coherence tomography angiography (SS-OCTA) for deep choroid visualization and choroidal vascular density (CVD) measurement.Methods: Healthy subjects and central serous chorioretinopathy (CSC) patients were recruited for macular SS-OCTA scans. We evaluated OCTA images at various depths to determine an optimal depth for visualizing choroidal vasculatures. We measured CVD with binarized OCTA images at the optimal depth. In healthy subjects, CVD was studied for its correlation with age, axial length (AL), and subfoveal choroidal thickness (SCT). In CSC eyes, CVD was compared with matched controls.Results: Ninety-one healthy eyes and 22 CSC eyes were included. SS-OCTA could display deep choroidal vasculatures as dark signals, with 100 μm beneath BM as the optimal depth. In healthy subjects, the CVD at 100 μm beneath BM (56.5 ± 10.9%) was significantly correlated with SCT (P = 0.004) but not with age (P = 0.49) or AL (P = 0.72). In CSC eyes, the CVD at 100 μm beneath BM (62.3 ± 6.6%) was larger than that in 22 matched controls (54.1 ± 8.0%) (P = 0.001). The difference remained statistically significant after adjusting for SCT (P = 0.02).Conclusions: SS-OCTA can be used for visualizing deep choroidal vasculatures. CVD measured by OCTA at 100 μm beneath BM is a useful parameter for quantifying choroidal vascular status. [ABSTRACT FROM AUTHOR]

Introduction: Swept-source optical coherence tomography (SS-OCT) imaging has ushered in an era of rapid and high-resolution imaging of the retinochoroid that provides detailed patho-anatomy of various layers. Areas covered: In this detailed review, the technology of swept-source imaging including its principles and working has been discussed. The applications of SS-OCT in various conditions including age-related macular degeneration, diabetic retinopathy, pachychoroid spectrum of diseases, and inflammatory vitreoretinal conditions have been elaborated. For each disease, a brief review of literature along with the utility of SS-OCT and optical coherence tomography angiography has been provided with supporting figures. The advantages of SS-OCT over spectral-domain have been discussed if there is sufficient evidence in the literature. Finally, the review summarizes the technological advantages in this field of retinal imaging. Expert opinion: The introduction of SS-OCT in our clinics has added newer devices in our armamentarium that can provide high-quality images of the deep retina and choroid. These advances in medical devices can help in improving our knowledge relating to the pathophysiology of diseases and their evolution. In the near future, rapid and high-resolution imaging may provide real-time volumetric information of the whole retina and the choroid that can be readily used for patient care. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationship between capsular bend type and posterior capsule opacification (PCO) at a three-dimensional (3D) level using high-speed swept-source optical coherence tomography (SS-OCT). Methods: This was a retrospective study. A total of 99 eyes that underwent standard cataract surgery with phacoemulsification 2 years ago were analyzed. Standard SS-OCT radial scanning was performed in all eyes and the obtained photos were used for morphological observations of the capsular bend-IOL complex, the adhesion of posterior capsule to the IOL optic, and the position of the anterior capsulorhexis. Digital retroillumination photographs were taken of the posterior capsule of each eye to evaluate PCO (scoring and area). Results: In terms of the PCO score and area, there was no statistical difference between eyes with complete and incomplete adhesion of posterior capsule to IOL (both P >.05), whereas the partial overlap group showed a statistical difference greater than the total overlap group (P <.05). There were two types of capsular bends, completed adhesion (CA) and incomplete adhesion (IA). IA was divided into funnel adhesion (IA-F), parallel adhesion (IA-P), and detached adhesion (IA-D). The incomplete adhesion index (IAI) varied between eyes and ranged from 0 to 1. The PCO score and area in the high IAI group (higher than 0.50) were significantly greater than the low IAI group (< 0.50) (P <.05). In addition, the PCO score and area were significantly higher in the cohort with at least one IA-D capsular bend in six districts to the group that did not have IA-D capsular bend (P <.05). Conclusions: Complete or incomplete adhesion of the posterior capsule to the IOL optic may not be necessary for the development of PCO. Our study suggests that capsular bend type may be used as an index to predict PCO. [ABSTRACT FROM AUTHOR]

Optical coherence tomography (OCT) is a widely used imaging technique in the micrometer regime, which gained accelerating interest in medical imaging in the last twenty years. In up-to-date OCT literature, certain simplifying assumptions are made for the reconstructions, but for many applications, a more realistic description of the OCT imaging process is of interest. In mathematical models, for example, the incident angle of light onto the sample is usually neglected or a plane wave description for the light–sample interaction in OCT is used, which ignores almost completely the occurring effects within an OCT measurement process. In this article, we make a first step to a quantitative model by considering the measured intensity as a combination of back-scattered Gaussian beams affected by the system. In contrast to the standard plane wave simplification, the presented model includes system relevant parameters, such as the position of the focus and the spot size of the incident laser beam, which allow a precise prediction of the OCT data. The accuracy of the proposed model—after calibration of all necessary system parameters—is illustrated by simulations and validated by a comparison with experimental data obtained from a 1300 nm swept-source OCT system.

Abstract Background To correlate retina-choroidal anatomy as assessed via swept-source OCT (SS-OCT) with retinal function as determined by best-corrected visual acuity (BCVA) and multifocal electroretinogram (mfERG). Methods Thirty-three eyes from 33 patients including 16 with neovascular AMD (nvAMD) and 17 controls were included. Patients were included in the present study after a complete ophthalmologic examination, including BCVA, slit-lamp study, intraocular pressure measurement, dilated fundus examination after tropicamide instillation, SD-OCT, SS-OCT, fundus photographs and mfERG. Age, sex, BCVA, number of anti-VEGF intravitreal injections in the nvAMD group, were recollected. Outer retinal and choroidal thickness were determined at the fovea and 500 μm temporal, superior, nasal and inferior. First-order response from mfERG was collected. P1 amplitude was recorded in R1, R2 and the average of R1 + R2. The measurements recollected from the SS-OCT, mfERG and BCVA were compared. Results Better BCVA was found with thicker outer retina foveal thickness (r = 0.349; P = 0.047), with thicker subfoveal choroidal thickness (r = 0.443; P = 0.010), and with higher amplitude in P1 at R1 (r = 0.346; P = 0.037). Outer retina foveal thickness did not correlate with P1 amplitude at R1 (r = 0.072; P = 0.692), R2 (r = 0.265; P = 0.137) either with the average P1 amplitude at R1 + R2 (r = 0.253; P = 0.156). A thicker subfoveal choroidal thickness was related with higher amplitude in P1 at R1 (r = 0.383; P = 0.028), R2 (r = 0.409; P = 0.018) and the average of R1 + R2 (r = 0.419; P = 0.015). Conclusions Choroidal thickness demonstrated a positive correlation with retinal function in the sample studied, so a thicker choroid is related to a better retinal function measured with mfERG and BCVA.

A 48-year-old female presented with complaints of recent onset diminution of vision of the left eye (OS) for the past 2 months. She was highly myopic and was using glasses for the past 30 years. Ocular examination revealed presence of a myopic fundus with high axial lengths in both the eyes. Fundus examination of the OS revealed a myopic tessellated fundus with prominent choroidal vessels and a blunted foveal reflex. There was a small pale whitish lesion just superior to the foveal center. Optical coherence tomography (OCT) scans (both horizontal and vertical) confirmed presence of dome-shaped maculopathy. There was subretinal fluid in the OS. A vertical OCT scan also revealed a subretinal hyperreflective material, which was confirmed to be due to a small mixed type 1 and type 2 choroidal neovascularization (CNV) on swept-source (SS) OCT angiography in the OS. The patient was given intravitreal injection of ranibizumab (0.5 mg/0.05 mL) in the OS. At 1-month follow-up, the subretinal fluid completely resolved. The CNV lesion regressed significantly on SS-OCT angiography. The best-corrected visual acuity improved from 20/80 to 20/20 in the OS, which was maintained at 3 months of follow-up. [ABSTRACT FROM AUTHOR]

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Abstract This study reviews the development of Swept-Source interferometers and compares systematically three different Swept-Source interferometer designs for biometric measurements of the eye. Principles characteristics, conveniences and accessibilities of the three developed systems are presented. The main difference between the three Swept-Source systems is the method of tuning the wavelength at the broadband optical amplifier. The implementation of a "quasi-phase-continuous method" (QPC) for wavelength tuning led to longer measuring depth but was more time-consuming. The wavelength tuning using a rotating polygon mirror scanner was faster. The wavelength tuning via Fourier Domain Mode Locking (FDML), where the tuning frequency f t of the filter must be matched to the inverse cavity roundtrip time τ , achieved the widest tuning range combined with a rather better resolution and signal to noise ratio (SNR). The swept sources were compared using a fiber-optic based Michelson interferometer setup. Measurements of a self-made human model eye demonstrate excellent capturing of the biometric data, with all interfaces of eye optical components and their contours being clearly detected. [ABSTRACT FROM AUTHOR]

We report the first use of swept-source microscope-integrated optical coherence tomography (SS-MIOCT) capable of live four-dimensional (4D) (three-dimensional across time) imaging intraoperatively to directly visualize tube shunt placement and trabeculectomy surgeries in two patients with severe open-angle glaucoma and elevated intraocular pressure (IOP) that was not adequately managed by medical intervention or prior surgery. We performed tube shunt placement and trabeculectomy surgery and used SS-MIOCT to visualize and record surgical steps that benefitted from the enhanced visualization. In the case of tube shunt placement, SS-MIOCT successfully visualized the scleral tunneling, tube shunt positioning in the anterior chamber, and tube shunt suturing. For the trabeculectomy, SS-MIOCT successfully visualized the scleral flap creation, sclerotomy, and iridectomy. Postoperatively, both patients did well, with IOPs decreasing to the target goal. We found the benefit of SS-MIOCT was greatest in surgical steps requiring depth-based assessments. This technology has the potential to improve clinical outcomes.

Purpose: Multimodality image analysis of two cases of torpedo maculopathy. Methods: Imaging with fundus photography, autofluorescence (AF), swept-source optical coherence tomography (OCT), en face OCT, and OCT angiography. Results: The basal diameter of the torpedo lesions was 1 mm × 2 mm. One case had a satellite lesion. Autofluorescence indicated variable loss of signal. Swept-source OCT and en face OCT demonstrated fundus excavation, attenuation of nuclear layers and disruption of the outer plexiform layer, loss of photoreceptors and a subretinal cleft. In one case, Sattler layer appeared extended at the cleft. Optical coherence tomography angiography indicated loss of flow in deep retinal vessels and increased flow in choroidal vessels surrounding the cleft. Conclusion: Multimodal imaging findings of torpedo maculopathy include disruption of the deep retinal capillary network, expansion of Sattler layer, and increased signal around the subretinal cleft. [ABSTRACT FROM AUTHOR]

• A new approach based on bandwidth compensation in the dual-sinusoidal signal driving mode of FFP-TF is introduced. • The new general insights into advanced problems associated with bandwidth extension are analyzed in detail. • A wavelength-swept laser source exhibiting a wide FWHM sweep range of 132.96 nm in 1.0 μm band using the new approach are demonstrated. • All of our techniques are general and can be applied to wavelength-swept laser sources as well as SS-OCT, but also more generally to fiber-optic sensing or interferometric applications. The bandwidth of rapidly wavelength-swept laser sources used in optical coherence tomography is a crucial parameter determining axial resolution. A novel driving method of fiber Fabry–Pèrot tunable filter (FFP-TF) using a dual-sinusoidal signal is developed. This new method is illustrated in detail, and the bandwidth of the optical spectrum generated by the sinusoidal signal modulation and bandwidth compensation is quantified. The efficiency of the proposed method is demonstrated by comparison of a sinusoidal signal and a dual-sinusoidal signal in serial configuration with an FFP-TF in contrast to wavelength-swept laser source. An operation of a wavelength-swept laser source with a sweep rate of 20 kHz over a 132.9 nm range at a center wavelength of 1076 nm is demonstrated. The general features of dual-sinusoidal signal are discussed, which is important for the design of future broadband wavelength-swept laser sources. While conventional sinusoidal signal driving yields a limited output bandwidth, an increase in bandwidth may be achieved in wavelength-swept laser sources with a dual-sinusoidal signal. [ABSTRACT FROM AUTHOR]

We report the first use of swept-source microscope-integrated optical coherence tomography (SS-MIOCT) capable of live four-dimensional (4D) (three-dimensional across time) imaging intraoperatively to directly visualize tube shunt placement and trabeculectomy surgeries in two patients with severe open-angle glaucoma and elevated intraocular pressure (IOP) that was not adequately managed by medical intervention or prior surgery. We performed tube shunt placement and trabeculectomy surgery and used SS-MIOCT to visualize and record surgical steps that benefitted from the enhanced visualization. In the case of tube shunt placement, SS-MIOCT successfully visualized the scleral tunneling, tube shunt positioning in the anterior chamber, and tube shunt suturing. For the trabeculectomy, SS-MIOCT successfully visualized the scleral flap creation, sclerotomy, and iridectomy. Postoperatively, both patients did well, with IOPs decreasing to the target goal. We found the benefit of SS-MIOCT was greatest in surgical steps requiring depth-based assessments. This technology has the potential to improve clinical outcomes. [ABSTRACT FROM AUTHOR]