Retinal applications of swept source optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA)

The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited.In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.     

Swept-source optical coherence tomography angiography findings in choroidal and retinal tumors

ObjectivesTo report the swept-source optical coherence tomography angiography (SS-OCTA) findings in choroidal and retinal tumors.MethodsA retrospective noncomparative interventional case series of 60 eyes having various choroidal and retinal tumors imaged with SS-OCTA (Topcon DR1 Triton Plus, Tokyo, Japan) between September 2018 and February 2020 was conducted. Inclusion criteria were tumor thickness <4 mm, tumor base diameter <10 mm, and tumor location at the posterior pole.ResultsChoroidal nevi usually demonstrated well-defined borders, hyperreflective internal structure, and no outer retinal involvement on SS-OCTA. Choroidal melanoma, in contrast to nevi, usually had ill-defined borders (p = 0.018), mixed hyperreflective–hyporeflective or hyperreflective internal structure (p = 0.014), and demonstrated outer retinal involvement (p < 0.001). Circumscribed choroidal hemangioma usually presented with well-defined borders, a hyperreflective internal tumor structure with multiple dilated interconnected tumor vessels intermixed with signal void areas representing connective tissue. Optic disc melanocytomas showed a hyporeflective plexus related to blocking of signal by the pigment and an intact radial peripapillary capillary network. There was flow on the surface and slightly deeper within the lesion on B-scan angiography overlay. Retinal astrocytic hamartomas had well-defined borders and a hyperreflective vascular plexus in the superficial and deep retina. Outer retina and choriocapillaris showed hyporeflective change due to shadowing/masking from calcium or high blood flow in the lesion.ConclusionsEach of the different retinal and choroidal tumors studied in this series presented with different SS-OCTA features to aid in the differential diagnosis of these conditions. Good quality images are obtained in patients with good fixation and tumors <3 mm in thickness located at the posterior pole.Subject terms: Outcomes research, Eye cancer     

急性Vogt-小柳-原田综合征黄斑相干光断层扫描观察

目的观察急性Vogt-小柳-原田综合征(VKH综合征)的相干光断层扫描(OCT)图像特征以及与临床的关联。探讨新型频域OCT在急性VKH综合征结构特征和定量分析中的临床价值。方法回顾分析临床确诊的急性VKH综合征21例(42眼)的OCT检查资料。所有患者接受最佳矫正视力(BCVA)、直接或间接检眼镜、裂隙灯显微镜+前置镜检查和荧光素眼底血管造影(FFA)检查。5线扫描(5 line Raster)模式下通过中心凹的水平+垂直两条扫描线的分析,对黄斑区视网膜各层结构变化的细微结构进行观察,用软件自带cliaper功能模块手工测量黄斑中心小凹厚度(FT)、神经上皮脱离高度(SRD)、神经上皮厚度(SRT)。在立方体(Cube)扫描模式下,采用软件自带的功能模块对黄斑中心厚度(CFT)、黄斑中心凹体积(V)、平均厚度(AT)进行测量。回顾分析时,重点分析黄斑区视网膜各层结构变化的细微结构,以及OCT图像特征与视力的相互关系。结果所有急性VKH综合征患者均可见后极部浆液性视网膜脱离。FT(r=0.2,P=0.00),SRD(r=0.83,P=0.00),CFT(r=0.81,P=0.000),AT(r=0.59,P=0.0001)和V(r=0.58,P=0.0001)值与初始视力呈负相关。视网膜色素上皮(RPE)上存在膜结构的35眼,平均视力为0.86±0.40logMAR,差于无膜结构的7眼(P=0.0074)。结论频域OCT可对急性VKH综合征特征性的黄斑改变进行定性及定量的观察,具有一定的诊断与鉴别诊断价值。VKH综合征的OCT图像特征性表现为:治疗前的渗出性视网膜脱离,"膜样"、"隔状"结构和RPE皱折,以及激素治疗后的"颗粒样"结构。存在"膜样"结构视力更差,FT和神经上皮脱离高度可能可反映脉络膜炎症的程度和疾病的严重程度。     

脉络膜肿瘤的OCT及OCTA表现

相干光断层扫描（optical coherence tomography,OCT）技术可用于脉络膜肿瘤（脉络膜黑色素瘤、脉络膜转移癌、脉络膜血管瘤、脉络膜骨瘤等）的观察和诊断,其对肿瘤表面形态、视网膜水肿程度、视网膜下液、光感受器层改变、视网膜结构的完整性、脉络膜厚度、异常反射结构等做定性及定量描述。相干光断层扫描血管成像（OCT angiography,OCTA）可对瘤体及其周围组织的视网膜脉络膜血流特点进行观察,并在一定程度上指导脉络膜肿瘤的治疗。（国际眼科纵览,2021, 45： 499-505）     

光学相干断层扫描血管成像中伪影的研究进展

光学相干断层扫描血管成像（OCTA）近年来在眼科得到广泛应用,其图像中存在伪影的问题也日益受到关注。伪影会影响OCTA的图像质量,引起临床上的误诊和错误的疗效判断。OCTA伪影的产生原理、分类、评价标准、伪影消除等问题的研究已取得初步进展,但仍需在未来的临床实践中进一步探索。     

Evaluation of optical coherence tomography angiography findings in patients with multiple sclerosis

Purpose:To evaluate optical coherence tomography angiography findings in patients with multiple sclerosis (MS).Methods:This prospective noninterventional study was conducted on 30 eyes of relapsing-remitting MS patients. Group (1) included 10 eyes with a history of optic neuritis (ON), group (2) included 10 eyes without any history of optic neuritis (MS-ON), and group (3) included 10 eyes of normal age/sex/refraction matched participants. Optical coherence tomography (OCT) and OCT-A (ZEISS Cirrus™ HD-OCT Model 4000 (Carl Zeiss-Meditec, Dublin, CA) of the optic disc were done for all patients.Results:The best-corrected visual acuity was diminished in MS cases, especially in patients with ON with P value <0.001. The retinal nerve fiber layer (RNFL) thickness showed a significant decrease in the average thickness and in all quadrants, notably the temporal quadrant in group 1 (P < 0.001). Ganglion cell layer thickness was diminished in average thickness and in all quadrants in both groups of MS, but only the first group showed statistical significance with P value <0.001). In respect to optic disc perfusion, Average, superficial, and deep vascular density index (AVDI, VDI 1, VDI 2) were statistically significantly lower in groups 1, 2 with (P-value < 0.001).Conclusion:Decreased vascular perfusion of the optic nerve in MS patients, especially in those with ON is strongly correlated with the damage of RNFL and ganglion cell layer detected by OCT.     

Retinal imaging by spectral optical coherence tomography

PURPOSE: To demonstrate applicability of high speed spectral optical coherence tomography (SOCT) method for imaging retinal pathologies in clinical conditions. METHODS: SOCT was performed in 67 eyes with different macular diseases. Examinations were carried out with the prototype SOCT instrument constructed in the Institute of Physics, Nicolaus Copernicus University, Toruń, Poland. A broadband superluminescent diode was used as a light source. RESULTS: The disturbances of retinal layer structure concerning mainly outer segments of photoreceptors were observed in case of central serous chorioretinopathy and choroidal neovascularization in age-related macular degeneration. Large drusen were often related to significant changes of outer nuclear layer thickness and reflectivity. CONCLUSIONS: SOCT detects small disturbances of the retinal structure and helps to precisely determine layers involved in different pathologies.     

Comparison of anterior segment optical coherence tomography angiography and fluorescein angiography for iris vasculature analysis

Graefe's Archive for Clinical and Experimental Ophthalmology - The aim of this study is to perform imaging of irises of different colors using spectral domain anterior segment optical coherence...