State-of-the-art retinal optical coherence tomography

OCT functions as a type of optical biopsy, providing information on retinal pathology in situ and in real time, with resolutions approaching that of excisional biopsy and histopathology. The development of ultrabroad-bandwidth and tunable light sources, as well as high-speed Fourier detection techniques, has enabled a significant improvement in ophthalmic optical coherence tomography (OCT) imaging performance. Three-dimensional, ultrahigh-resolution OCT (UHR OCT) can provide information on intraretinal morphology that is not available from any other non-invasive diagnostic. High-speed imaging facilitates the acquisition of three-dimensional data sets (3D-OCT), thus enabling volumetric rendering and the generation of OCT fundus images that precisely and reproducibly register OCT images to fundus features. The development of broadband light sources emitting at new wavelengths, e.g., approximately 1050 nm, has enabled not only 3D-OCT imaging with enhanced choroidal visualization, but also reduced scattering losses and improved OCT performance in cataract patients. Adaptive optics using high-stroke, deformable mirror technology to correct higher order aberrations in the human eye, in combination with specially designed optics to compensate chromatic aberration along with three-dimensional UHR OCT, has recently enabled in vivo cellular-resolution retinal imaging. In addition, extensions of OCT have been developed to enhance image contrast and to enable non-invasive depth-resolved functional imaging of the retina, thus providing blood flow, spectroscopic, polarization-sensitive and physiological information. Functional OCT promises to enable the differentiation of retinal pathologies via localized, functional retinal response or metabolic properties. These advances promise to have a powerful impact on fundamental as well as clinical studies.     

Detecting the inner and outer borders of the retinal nerve fiber layer using optical coherence tomography

BACKGROUND: The purpose of this study was to develop a new algorithm to detect the inner and outer borders of the retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT).METHODS: A program featuring a new algorithm was developed using a commercially available software development environment. The algorithm searches for peaks on each sampling line instead of applying conventional thresholding techniques. All circular peripapillary OCT images obtained at the New York Eye and Ear Infirmary from October 1996 to December 2000 were analyzed using the new and the commercially available algorithms.RESULTS: Four hundred one images of 98 patients were analyzed. The detection error rate (defined as number of scans with five consecutive sampling lines with disrupted RNFL borders) was significantly lower with the new algorithm (25/401 images, 6.2%) than with the commercially available algorithm (70/401 images, 17.5%) (P=0.018, chi-square).CONCLUSION: The new algorithm improved the ability of OCT to detect the borders of the RNFL.     

应用光学相干断层扫描血管成像（OCTA）评估糖尿病患者早期黄斑区视网膜微循环

目的　应用光学相干断层扫描血管成像（optical coherence tomography angiography,OCTA）观察糖尿病患者早期黄斑中心凹无血管区（foveal avascular zone,FAZ）面积和黄斑区血流密度（macular vascular density,MVD）的改变及其临床意义。方法　回顾性病例研究。收集33例46眼糖尿病患者纳入研究,依据糖尿病视网膜病变国际临床分期标准将患眼分为两组,其中无糖尿病视网膜病变（no-diabetic retinopathy,NDR）组13例20眼和非增生期糖尿病视网膜病变（nonproliferative diabetic retinopathy,NPDR）组20例26眼。另选取年龄相匹配的26人（40眼）健康者作为对照组。所有受试者均接受OCTA对黄斑区视网膜行3 mm×3 mm 范围的模式扫描,获得4个层面黄斑血流密度图,同时测量FAZ面积和MVD。结果　NDR组和NPDR组FAZ面积分别为（0.392±0.028）mm²、（0.410±0.019）mm²,与对照组（0.314±0.025）mm²相比差异均有统计学意义（均为P=0.000）;NDR组和NPDR组之间的FAZ面积比较,差异有统计学意义（P=0.010）。NDR组和NPDR组的表层视网膜、深层视网膜、外层视网膜及脉络膜毛细血管层的MVD分别是0.500±0.012、0.553±0.007、0.393±0.005、0.651±0.006和0.484±0.012、0.522±0.007、0.397±0.007、0.642±0.007,与对照组（0.518±0.014、0.572±0.008、0.385±0.005、0.666±0.007）比较,差异均有统计学意义（均为P=0.000）;NDR组和NPDR组表层视网膜、深层视网膜及脉络膜毛细血管层MVD比较,差异均有统计学意义（均为P=0.000）,但两组外层视网膜MVD比较,差异无统计学意义（P=0.065）。结论　应用OCTA检查提示糖尿病患者早期黄斑区视网膜的微循环障碍,且随着病情的进展而变化。     

Longitudinal analysis of retinal changes after branch retinal artery occlusion using optical coherence tomography.

BACKGROUND: Branch retinal artery occlusion (BRAO) causes inner retinal ischemia leading to permanent inner retinal dysfunction and visual field loss in affected retinal sectors. Optical coherence tomography (OCT) offers a novel way to evaluate in vivo retinal morphologic changes in BRAO in both acute and longitudinal phases. This case report describes OCT findings in BRAO at acute presentation and at follow-up, including the longitudinal evaluation of retinal and peripapillary retinal nerve fiber layer (RNFL) thickness. CASE REPORT: A 58-year-old white man with an acute branch retinal artery occlusion was examined by OCT at initial presentation and at 2, 4, and 8 months. At initial presentation, OCT line scan showed thickening and hyper-reflectivity of the inner retina with shadowing of photoreceptor and retinal pigment epithelial layers. At 2 months, hyper-reflectivity and thickening were reduced. At 4 months, the inner retina showed no hyper-reflectivity and was attenuated. Peripapillary RNFL thickness was reduced in corresponding sectors. Findings at the 8-month follow-up were unchanged from the 4-month visit. CONCLUSIONS: OCT provides useful information regarding the evolution of inner retinal attenuation in BRAO. Differential diagnosis of sectoral peripapillary RNFL thinning should include previous BRAO.     

POAG患者视网膜各层厚度的OCT分析

目的利用RTVue OCT对POAG患者黄斑区视网膜各层厚度进行分析,尤其是视神经节细胞层,探讨其在原发性开角型青光眼诊断中的价值。方法前瞻性对照研究。临床诊断为POAG的病例76例（91眼）纳入本研究,分为早期30例（30眼）,中期25例（29眼）,晚期21例（32眼）;选择32例（32眼）年龄、性别构成相匹配的健康体检者作为正常对照组。采用RTVue OCT对受检眼黄斑区视网膜进行扫描,用自编程序图像处理软件将视网膜结构分为9层,早、中、晚期POAG与正常对照组黄斑区视网膜各层厚度比较采用LSD-t检验。结果早期POAG组视网膜神经纤维层（RNFL）、节细胞层（GCL）平均厚度分别为（31.6±9.2）μm、（33.9±5.0）μm,较对照组薄（P＜0.05）,中期POAG组RNFL、GCL平均厚度分别为（31.2±3.4）μm、（34.1±3.9）μm,较正常组薄（P＜0.05）;晚期POAG组RNFL、GCL、内丛状层（IPL）、锥杆细胞内节（IS）、全视网膜（TR）平均厚度分别为（18.8±7.6）μm、（24.2±7.9）μm、（38.0±6.4）μm、（22.8±4.4）μm、（299.5±15.1）μm,均较正常组薄（均P＜0.05）;INL平均厚度（39.1±6.6）μm,较正常组厚（P＜0.05）。结论POAG患者黄斑区视网膜厚度明显变薄,早期POAG对GCL的影响尤为突出,结合临床有助于POAG的早期诊断。     

Analysis of retinal findings of acute retinal necrosis using optical coherence tomography

PURPOSE: To analyze the retinal findings in patients with ARN, optical coherence tomography (OCT) was performed. METHODS: Seven patients (7 eyes) with ARN were studied using OCT. RESULTS: OCT images depicted highly reflective areas in the inner layers of the retina in all seven cases, corresponding with the yellowish-white lesions of the retina in the acute phase. Disorganization of the retinal structure was also observed in these retinal lesions, especially in cases with severe inflammation. Subretinal changes including retinal exudate and/or fluid were observed in only one case. After regression of the yellowish-white lesions in the retina, a significant reduction in retinal thickness was observed on OCT. CONCLUSIONS: OCT permits the detection of full-thickness retinal necrosis in the acute phase and complete absence of retinal structure in the resolution phase, corresponding with the yellowish-white lesions seen in patients with ARN.     

Optical coherence tomography analysis of the inner retinal layers in children

Objective

The aim of this study was to determine a correlation between the optic nerve head (ONH) area, the peripapillary retinal nerve fibre layer (pRNFL), and the ganglion cell inner plexiform layer (GCIPL) thicknesses, measured by optical coherence tomography (OCT) in children.

Congenital retinal macrovessel: atypical presentation using optical coherence tomography

To describe a congenital retinal macrovessel with macular thickening. This case was investigated using fundus photography, fluorescein angiography, Spectralis optical coherence tomography and a 10–2 visual field test. A 23-year-old man was referred to our clinic with decreased vision in the right eye. Fundus examination of the right eye revealed a congenital retinal macrovessel that originated inferior to the superotemporal branch of the central retinal vein. Using fluorescein angiography, early filling and delayed emptying of the aberrant vein were observed. Spectralis optical coherence tomography demonstrated macular thickening and was supported by a 10–2 visual field test that revealed a relative scotoma corresponding to the same location. At the 18-month follow-up, visual acuity remained stable. Although rare, this case demonstrated that macular thickening can cause decreased visual acuity in the presence of a congenital retinal macrovessel.     

光学相干断层扫描血管成像量化分析糖尿病患者黄斑区毛细血管参数

目的：应用光学相干断层扫描血管成像技术(OCTA)量化2型糖尿病患者黄斑区毛细血管的早期变化。方法：回顾性病例研究。分别纳入49名健康受试者、52例无视网膜病变的2型糖尿病患者(noDR)和43例轻度非增殖性糖尿病视网膜病变(mNPDR)患者，并得到在黄斑区3 mm×3 mm浅层毛细血管丛和深层毛细血管丛的OCTA图像。去除大血管后分别计算毛细血管灌注密度、血管长度密度(VLD)和平均血管直径(AVD)并进行比较。应用受试者工作特征曲线评估该参数监测2型糖尿病患者视网膜微血管早期改变的能力。结果：比较三组间VLD和AVD，差异均有统计学意义(P<0.001)。与健康受试者相比，noDR组的AVD均显著增加(P<0.05)。mNPDR组患者深层及浅层的VLD较noDR组显著下降(均P<0.01)。深层AVD鉴别noDR组与健康受试者的曲线下面积(AUC)为0.796，鉴别mNPDR组和健康受试者的AUC最高为0.920，其次为深层VLD(AUC=0.899)，显著高于其他参数。结论：在糖尿病视网膜病变的临床前阶段，2型糖尿病患者的深层及浅层AVD均显著高于健康人，VLD均显著高于mNPDR患者。与健康人相比，深度AVD较其他参数更能检出noDR患者早期视网膜毛细血管的变化。     

Objective analysis of retinal function in HIV-positive children without retinitis using optical coherence tomography

PURPOSE: To assess the retinal nerve fiber layer thickness in children with human immunodeficiency virus disease without cytomegalovirus retinitis or visual symptoms. METHODS: Thirty-eight eyes of 19 human immunodeficiency virus-positive children (group A) with visual acuity of 20/20 or better, normal color vision testing and no ophthalmoscopically detectable disorders were prospectively examined. All subjects of group A had no history of cytomegalovirus retinitis and CD4 counts consistently above 100. Patients in group B (40 eyes of 21 patients) were human immunodeficiency virus-negative age-matched control subjects. Thickness of retinal nerve fiber layer along a 3.4-mm-diameter circle centered on the optic nerve head was evaluated using third-generation optical coherence tomography. CD8 T-lymphocyte count, presence of systemic infection, hemoglobin, hematocrit and serum beta-microglobulin levels were also recorded. RESULTS: The mean overall retinal nerve fiber layer thickness in groups A and B were 89.2 +/- 24.01 microm and 102.82 +/- 29.168 microm (SD) respectively. The difference was considered extremely significant (P < 0.0001). Group A had significantly thinner average nerve fiber layer in temporal, nasal, superior and inferior retinal areas. CONCLUSIONS: Significant retinal nerve fiber layer thinning occurs in human immunodeficiency virus-positive children with no visual impairment or ophthalmologic evidence or retinitis.     

Analysis of retinal flecks in fundus flavimaculatus using optical coherence tomography

BACKGROUND/AIM: Retinal flecks are commonly observed in both Stargardt disease and fundus flavimaculatus (FFM). The aim was to determine the precise localisation of these flecks within the retinal layers using Stratus optical coherence tomography (OCT). METHODS: A prospective observational case series. A complete ophthalmological examination, including autofluorescence, fluorescein angiography (FA), and Stratus OCT (Carl Zeiss) was performed in 49 eyes of 26 consecutive patients with FFM. Six to 12 Stratus OCT linear scans focused on the retinal flecks were performed in each eye. RESULTS: The age at presentation ranged from 23 years to 71 years and visual acuity ranged from 20/20 to 20/400. Hyper-reflective deposits classified into two types were observed on Stratus OCT: type 1 lesions (94% of eyes) presented as dome-shaped deposits located in the inner part of the retinal pigment epithelium (RPE) layer and type 2 lesions (86% of eyes) presented as small linear deposits located at the level of the outer nuclear layer and clearly separated from the RPE layer. CONCLUSIONS: Stratus OCT is a non-invasive instrument that provides new information on the location of flecks in FFM. The location of type 2 lesions is quite unusual among macular dystrophies; OCT may therefore be useful in the diagnosis of retinal flecks in some cases of FFM.     

Differentiation of degenerative retinoschisis from retinal detachment using optical coherence tomography

OBJECTIVE: To assess the potential of optical coherence tomography (OCT) to differentiate retinoschisis from retinal detachment. Optical coherence tomography is a noninvasive, noncontact imaging method that produces high-resolution, cross-sectional images of ocular tissue. DESIGN: Retrospective case series. PARTICIPANTS: Thirteen eyes of 12 patients with the differential diagnosis of retinoschisis versus retinal detachment. METHODS: Differentiation between retinoschisis and retinal detachment was established from both ophthalmoscopic and OCT examinations. MAIN OUTCOME MEASURE: Ability of OCT to differentiate retinoschisis from retinal detachment was measured. RESULTS: Thirteen eyes of 12 patients with retinal elevation were examined with OCT. The cross-sectional view produced by OCT was effective in distinguishing retinoschisis from retinal detachment. Optical coherence tomography images of retinoschisis show a splitting of the neurosensory retina. The OCT images of retinal detachment show separation of full-thickness neurosensory retina from the retinal pigment epithelium band. The OCT images correlated with the clinical impression in all 13 cases. CONCLUSIONS: Based on this series of cases, OCT is a potentially useful new test that may be used to distinguish retinoschisis from rhegmatogenous retinal detachment.     

糖尿病患者视网膜神经纤维层OCT测量的形态学观察

背景 传统的观点认为,糖尿病视网膜病变（DR）的主要病理机制是视网膜的微血管病变,但近年来发现糖尿病患者的视功能改变发生于DR的微血管病变发生之前,传统的观点无法解释糖尿病患者在出现可辨认的血管改变之前已有视功能改变的现象. 目的 应用频域光学相干断层扫描（OCT）观察无视网膜血管改变的糖尿病患者、非增生性糖尿病视网膜病变（NPDR）患者视网膜神经纤维层（RNFL）厚度的改变,分析糖尿病患者RNFL厚度与DR的关系. 方法 收集2012年10月至2013年9月于山西省眼科医院就诊且确诊的2型糖尿病患者56例60眼,按DR国际临床分型标准分为非糖尿病视网膜病变（NDR）组26例30眼和NPDR组（轻中度NPDR）30例30眼,同期纳入年龄和性别匹配的健康志愿者30人30眼作为对照.应用OCT对受试者行RNFL厚度测量,包括视盘周围及中心凹周围视网膜360°平均RNFL厚度及鼻上、颞上、颞侧、颞下、鼻下、鼻侧区域的RNFL厚度,比较各组患者RNFL厚度的变化. 结果 NDR组、NPDR组和正常对照组受试者视盘周围平均RNFL厚度分别为（97.46±8.65）、（100.69±16.35）和（109.22±8.69）μm,其中NDR组、NPDR组受试者视盘周围平均RNFL厚度值均低于正常对照组,差异均有统计学意义（P=0.001、0.006）;NDR组视盘周围各象限RNFL厚度均较正常对照组变薄,颞上、颞侧、颞下和鼻下象限RNFL厚度的差异均有统计学意义（P=0.001、0.001、0.001、0.010）;NPDR组视盘周围各象限RNFL厚度均较正常对照组变薄,其中颞上、鼻侧区域RNFL厚度的差异均有统计学意义（P=0.001、0.046）.NDR组、NPDR组和正常对照组平均黄斑区RNFL厚度分别为（33.47±3.39）、（36.81±3.21）、（38.18±2.16）μm,NDR组、NPDR组受试者黄斑区平均RNFL厚度值均低于正常对照组,其中NDR组与正常对照组比较差异有统计学意义（P=0.001）;NDR组黄斑区各区域RNFL厚度较正常     

Quantification of retinal microvascular parameters by severity of diabetic retinopathy using wide-field swept-source optical coherence tomography angiography

Graefe's Archive for Clinical and Experimental Ophthalmology - To investigate the diagnostic utility of microvascular parameters for grading the severity of diabetic retinopathy (DR) with a...