Noninvasive volumetric imaging and morphometry of the rodent retina with high-speed, ultrahigh-resolution optical coherence tomography

PURPOSE: To demonstrate high-speed, ultrahigh-resolution optical coherence tomography (OCT) for noninvasive, in vivo, three-dimensional imaging of the retina in rat and mouse models. METHODS: A high-speed, ultrahigh-resolution OCT system using spectral, or Fourier domain, detection has been developed for small animal retinal imaging. Imaging is performed with a contact lens and postobjective scanning. An axial image resolution of 2.8 mum is achieved with a spectrally broadband superluminescent diode light source with a bandwidth of approximately 150 nm at approximately 900-nm center wavelength. Imaging can be performed at 24,000 axial scans per second, which is approximately 100 times faster than previous ultrahigh-resolution OCT systems. High-definition and three-dimensional retinal imaging is performed in vivo in mouse and rat models. RESULTS: High-speed, ultrahigh-resolution OCT enabled high-definition, high transverse pixel density imaging of the murine retina and visualization of all major intraretinal layers. Raster scan protocols enabled three-dimensional volumetric imagingand comprehensive retinal segmentation algorithms allowed measurement of retinal layers. An OCT fundus image, akin to a fundus photograph was generated by axial summation of three-dimensional OCT data, thus enabling precise registration of OCT measurements to retinal fundus features. CONCLUSIONS: High-speed, ultrahigh-resolution OCT enables imaging of retinal architectural morphology in small animal models. OCT fundus images allow precise registration of OCT images and repeated measurements with respect to retinal fundus features. Three-dimensional OCT imaging enables visualization and quantification of retinal structure, which promises to allow repeated, noninvasive measurements to track disease progression, thereby reducing the need for killing the animal for histology. This capability can accelerate basic research studies in rats and mice and their translation into clinical patient care.     

Spatial correlation of mouse photoreceptor-RPE thickness between SD-OCT and histology

Spectral Domain Optical Coherence Tomography (SD-OCT) applied to the mouse retina has been limited due to inherent movement artifacts and lack of resolution. Recently, SD-OCT scans from a commercially available imaging system have yielded retinal thickness values comparable to histology. However, these measurements are based on single point analysis of images. Here we report that using the Spectralis HRA + OCT Spectral Domain OCT and Fluorescein Angiography system (Heidelberg Engineering, Heidelberg, Germany), retinal thickness of linear expanses from SD-OCT data can be accurately assessed. This is possible by the development of a Spectralis-compatible ImageJ plug-in that imports 8-bit SLO and 32-bit OCT B-scan images, retaining scale and segmentation data and enabling analysis and 3D reconstruction. Moreover, mouse retinal layer thickness values obtained with this plug-in exhibit a high correlation to thickness measurements from histology of the same retinas. Thus, use of this ImageJ plug-in results in reliable quantification of long retinal expanses from in vivo SD-OCT images.     

Monitoring mouse retinal degeneration with high-resolution spectral-domain optical coherence tomography

Progression of retinal degeneration in a mouse model was studied in vivo with high-resolution spectral-domain optical coherence tomography (SD-OCT). Imaging in 3D with high depth resolution (<3 mum), SD-OCT resolved all the major layers of the retina of control C57BL/6J mice. Images of transgenic mice having a null mutation of the rhodopsin gene revealed the anatomical consequences of retinal degeneration: thinning of the outer retina, including the outer plexiform layer (OPL), outer nuclear layer (ONL), and inner and outer segments (IS/OS). We monitored the progression of retinal degeneration in rd1 mice (C3H/HeJ) by periodically imaging the same mice from the time the pups opened their eyes on P13 to P34. SD-OCT images showed that the outer retina (OPL, ONL, IS/OS) had already thinned by 73% (100 to 27 mum) at eye opening. The retina continued to degenerate, and by P20 the outer retina was not resolvable. The thickness of entire retina decreased from 228 mum (control) to 152 mum on P13 and to 98 mum by P34, a 57% reduction with the complete loss in the outer retina. In summary, we show that SD-OCT can monitor the progression of retinal degeneration in transgenic mice.     

A Novel Technique of Adjusting Segmentation Boundary Layers to Achieve Comparability of Retinal Thickness and Volumes between Spectral Domain and Time Domain Optical Coherence Tomography

Purpose. The quantitative assessment of retinal thickness and volume varies according to the optical coherence tomography (OCT) machine used due to differences in segmentation lines. We describe a novel method of adjusting the segmentation lines of spectral-domain OCT (SD-OCT) to enable comparison with time-domain OCT (TD-OCT), and assess factors affecting its accuracy. Methods. In a prospective study, SD-OCT (Spectralis OCT) and TD-OCT (Stratus OCT) were sequentially performed on 200 eyes of 100 healthy individuals. Central retinal thickness (CRT), central point thickness (CPT), and 1-mm volume of the Early Treatment Diabetic Retinopathy Study grid were compared between the two machines. The segmentation lines on SD-OCT were manually adjusted by a trained operator and the parameters compared again with TD-OCT. Results. The mean CRTs of Spectralis and Stratus were significantly different (268.2 μm vs. 193.9 μm, P < 0.001). After adjustment of segmentation lines, the mean adjusted Spectralis CRT was 197.3 μm, with the difference between SD-OCT and TD-OCT measurements decreasing from 74.3 μm to 3.4 μm (P < 0.001). The difference between the adjusted Spectralis and Stratus CRTs was smallest for high myopes (≤ -6.0 diopters [D]) compared with those with moderate and low myopia (1.5 μm vs. 3.5 μm and 4.6 μm, respectively; P < 0.001). Similar trends were obtained for central 1-mm volumes and CPT. Interoperator and intraoperator repeatability for adjustment of the segmentation lines were good, with an intraclass correlation of 0.99 for both. Conclusions. Manual adjustment of SD-OCT segmentation lines reliably achieves retinal thickness and volume measurements that are comparable to that of TD-OCT. This is valuable to allow comparisons in multicenter clinical trials where different OCT machines may be used.     

Biometric measurement of the mouse eye using optical coherence tomography with focal plane advancement

PURPOSE: To demonstrate that high-resolution biometry is possible in mouse eyes in vivo, using real-time OCT with focal plane advancement by a stepper motor. METHODS: OCT images of eyes were taken from nine 29-day-old C57BL/6 mice(18 eyes) on two consecutive days. A custom-built real-time OCT instrument with a stepper motor was used to advance the focal plane from the corneal apex to the retina along the ocular axis. The ocular dimensions were determined by advancement of the stepper motor as it displayed on the OCT scan images. RESULTS: OCT images of the entire eye, including the cornea, anterior chamber, lens, vitreous chamber, and retina, were successfully obtained from both eyes of all mice. The measured average corneal thickness from 18 eyes at the age of 29 days was 90.8+/-4.6microm, anterior chamber depth 707.4+/-21.4microm, lens thickness 1558.7+/-18.0microm, vitreous chamber depth 707.4+/-21.4microm and retinal thickness was 186.9+/-15.1microm. Total axial length (from the corneal apex to the nerve fiber layer of the retina) was 3003.3+/-44.1microm. None of them were significantly different if measured on two consecutive days, and no significant differences were found between measurements in the left and right eyes. CONCLUSION: By focal plane advancement of a real-time OCT instrument through the mouse eye, highly repeatable measurements of the ocular dimensions were obtained. This novel method may be used to study small animal models of normal and abnormal eye development.     

The interpretation of optical coherence tomography images of the retina.

PURPOSE: To determine the relationship between optical coherence tomography (OCT) images of the retina and retinal substructure in vitro and in vivo. METHODS: In vitro, OCT images of human and bovine retina were acquired after sequential excimer laser ablation of the inner retinal layers. Measurements of bands in the OCT images were compared with measurements of retinal layers on histology of the ablated specimens. In vivo, OCT images were acquired of retinal lesions in which there was a displacement of pigmented retinal pigment epithelial (RPE) cells: retinitis pigmentosa and laser photocoagulation (eight eyes each). RESULTS: The mean thickness of human inner OCT bands (131 microm; 95% confidence interval [CI], 122-140 microm) was 7.3 times that of the retinal nerve fiber layer (RNFL). This band persisted despite ablation greater than 140 microm. The inner aspect of the outer OCT band corresponded to the apical RPE, but the mean thickness of this band in human tissue (55 microm; 95% CI, 48-62 microm) was 2.6 times the thickness of the RPE-choriocapillaris complex. OCT measurement of total retinal thickness was accurate (coefficient of variance, 0.05) and precise (coefficient of correlation with light microscopy, 0.98). Hyperpigmented lesions gave rise to high signal, attenuating deeper signal; hypopigmented lesions had the opposite effect on deeper signal. CONCLUSIONS: The inner band is not RNFL specific, partly consisting of a surface-related signal. The location, not thickness, of the outer band corresponds to RPE melanin. Given the additional effect of polarization settings, precise OCT measurement of specific retinal layers is currently precluded.     

Noninvasive imaging by optical coherence tomography to monitor retinal degeneration in the mouse.

PURPOSE: Optical coherence tomography (OCT) is a high-resolution imaging technique that measures the intensity of backscattered light from biological microstructures in living tissue. The objective was to evaluate OCT as a routine, noninvasive technique for quantitative measurements of retinal thickness and detachment in small animal models of retinal degenerative diseases. METHODS: An OCT scanning unit was designed and built to visualize retinal tissue from rodents at high resolution in vivo. Several normal and retinal degeneration (rd) mouse strains with different pigmentation, as well as a transgenic mouse strain that carries a wild-type beta-PDE gene in an rd/rd background, were analyzed at different ages. Retinal detachment was induced by subretinal injection of saline. Retinal function was evaluated by full-field ERG, and then each retina was cross-sectionally scanned by OCT. OCT image analysis and measurements of retinal thickness were performed. Animals were then killed and retinal histology was documented. RESULTS: OCT images of the mouse retina revealed structural landmarks allowing assignment of retinal structures. There was no difference in the OCT pattern between pigmented and nonpigmented mice. Changes in the retinal thickness measured by OCT correlated very well with the loss in function measured by ERG and histology in rd/rd and rd/rd/tg(+) transgenic mice at a variety of ages. In addition, retinal detachment caused by surgery was easily visualized and observed by OCT imaging. CONCLUSIONS: OCT imaging is applicable to the mouse retina. There is excellent agreement between the retinal thickness measured by OCT, ERG amplitude, and retinal histology, thus validating OCT imaging as a sensitive and noninvasive tool for monitoring the structural progression of retinal diseases in rodent models. OCT also appears useful for visualizing retinal detachments in the mouse.     

Quantitative thickness measurement of retinal layers imaged by optical coherence tomography

PURPOSE: To report an image analysis algorithm that was developed to provide quantitative thickness measurement of retinal layers on optical coherence tomography (OCT) images. DESIGN: Prospective cross-sectional study. METHODS: Imaging was performed with an OCT3 commercial instrument in 10 visually normal healthy subjects. A dedicated software algorithm was developed to process the raw OCT images and detect the depth location of peaks from intensity profiles. Quantitative thickness measurements of three retinal layers, in addition to total retinal thickness, were derived. Total retinal thickness measurements obtained by the algorithm were compared with measurements provided by the standard OCT3 software. RESULTS: The total retinal thickness profile demonstrated foveal depression, corresponding to normal anatomy, with a thickness range of 160 to 291 microm. Retinal thickness measured by the algorithm and by the standard OCT3 software were highly correlated (R = 0.98). The inner retinal thickness profile predictably demonstrated a minimum thickness at the fovea, ranging between 58 to 217 microm along the 6-mm scan. The outer retinal thickness profile displayed a maximum thickness at the fovea, ranging between 66 to 107 microm along the 6-mm scan. The photoreceptor outer segment thickness profile was relatively constant along the 6-mm scan through the fovea, ranging between 42 to 50 microm. The intrasubject variabilities of the inner retina, outer retina, and photoreceptor outer segment thickness was 14, 10, and 6 microm, respectively. CONCLUSIONS: Thickness measurements of retinal layers derived from OCT images have potential value for objectively documenting disease-related retinal thickness abnormalities and monitoring progressive changes over time.     

Associations of macular thickness in spectral-domain OCT with ocular and systemic cardiovascular parameters - The MIPH Eye &amp; Health Study

Purpose

Beyond in-vivo histological analysis of retinal tissue, optical coherence tomography (OCT) allows quantitative image analysis. This study evaluates associations of macular retinal thickness measured with spectral-domain OCT (SD-OCT) and ocular and systemic cardiovascular parameters in adult subjects.

Methods

An epidemiological cross-sectional study was performed in the staff of a European high-tech company. Examination of known cardiovascular risk factors including biochemical blood analysis was performed, and ocular parameters such as refraction, tonometry, SD-OCT imaging of the macula and cornea, and fundus photography were evaluated. Retinal thickness measurements were evaluated according to the ETDRS grid. Associations of macular retinal thickness and systemic cardiovascular and ocular parameters were calculated by multivariate analysis using SPSS software.

Results

Four hundred and twenty-four probands were included. Macular thickness measurement were significantly associated with gender and refraction. Female persons had thinner retinal thickness in all zones. Macular thickness decreased with increasing myopia in all perifoveal measurements. Outer perifoveal measurements were associated with keratometry; a flatter corneal radius was linked to a thinner retina. Tonometry and systemic cardiovascular risk factors were not associated with macular retinal thickness in multivariate analysis (p?>?0.05).

Conclusions

Macular retinal thickness is associated with refraction and gender; cardiovascular risk factors or tonometry do not influence macular retinal thickness measurements. Keratometry might influence outer zone measurements. Our findings provide a dataset for quantitative evaluation of SD-OCT, and evaluate influencing factors.

     

Retinal nerve fiber layer assessment using optical coherence tomography with active optic nerve head tracking

PURPOSE: To develop an eye-motion-tracking optical coherence tomographic (OCT) method and assess its effect on image registration and nerve fiber layer (NFL) thickness measurement reproducibility. METHODS: A system capable of tracking common fundus features based on reflectance changes was integrated into a commercial OCT unit (OCT II; Carl Zeiss Meditec, Inc., Dublin, CA) and tested on healthy subjects and patients with glaucoma. Twenty successive peripapillary NFL scans were obtained with tracking and 20 without tracking, for 40 images in each session for each eye. Subjects participated in one session on three different days. Composite OCT scans and composite fundus images were generated for assessment of eye tracking. NFL thickness measurement reproducibility was also assessed. RESULTS: Seven healthy and nine glaucomatous eyes of 16 subjects were recruited. A qualitative assessment of composite OCT scans and composite fundus images showed little motion artifact or blurring along edges and blood vessels during tracking; however, those structures were less clearly defined when tracking was disengaged. There was no significant reproducibility difference with and without tracking in both intra- and intersession NFL measurement SD calculations in any location. The mean retinal pixel SD was significantly smaller with tracking than without (490.9 +/- 19.3 microm vs. 506.4 +/- 31.8 microm, P = 0.005, paired t-test). CONCLUSIONS: A retinal-tracking system was successfully developed and integrated into a commercial OCT unit. Tracking OCT improved the consistency of scan registration, but did not influence NFL thickness measurement reproducibility in this small sample study.     

频域OCT外层视网膜高反射光带的临床研究进展

随着高分辨率频域OCT(SD-OCT)技术在临床上的广泛使用,眼科工作者可对黄斑区外层视网膜成像进行更加详细的解读,表现为外层视网膜可分辨的高反射光带从时域OCT(TD-OCT)的3条到现在清晰可辨的4条,从内向外依次是外界膜(ELM)、光感受器细胞内外节(IS/OS)交界面连接带、视锥细胞外节末梢(COST)和视网膜色素上皮(RPE).从对应的视网膜组织学结构上来看,ELM、IS/OS和COST均在光感受器细胞之内,因此,这3条高反射光带的完整直接关系到光感受器细胞的完整性及其功能状态.利用SD-OCT探讨各类视网膜疾病光感受器细胞的状态与功能、损伤与修复特点的临床研究已成为眼科研究领域的热点之一.本文就近年来对ELM、IS/OS和COST这3条高反射光带在黄斑裂孔、特发性视网膜前膜、孔源性视网膜脱离以及年龄相关性黄斑变性等眼底疾病中的临床研究成果进行综述.     

视觉发育关键期大鼠视网膜频域OCT测量值的变化特征

背景人类和哺乳动物视觉发育关键期内视网膜处于发育阶段,其各个亚层的正确排列以及细胞的准确定位是视觉信息正常传递的基础之一。频域光学相关断层扫描（SD—OCT）可活体测量并连续观察大鼠视网膜厚度的变化。目的了解视觉发育关键期内SD大鼠视网膜厚度的变化规律。方法选择新生SD大鼠30只,其中10只于出生后14、18、21、24、42d进行双眼眼底SD—OCT扫描,对视网膜厚度以及部分亚层包括内界膜（ILM）至内丛状层（IPL）、内核层（INL）、外核层（ONL）至视网膜色素上皮（RPE）层的厚度进行生物测量。另取20只SD大鼠,分别于14、18、21、24、42d各处死4只大鼠并摘除双眼,制作石蜡切片行苏木精一伊红染色,对视网膜厚度以及部分亚层结构进行测量。并对两种方法测量数据的相关性进行评价。结果大鼠视网膜CirrusHD—OCT图像由内向外可显示视网膜IPL、INL、外丛状层（OPL）、ONL、光感受器内节／外节（IS／OS）层以及RPE层等结构。比较各个时间点的视网膜厚度、ILM至IPL厚度、INL厚度以及ONL至RPE层厚度,差异均有统计学意义（F=15．425,P=0．000;F=3．973,P=0．007;F=17．529,P：0．000;F=7．038,P=0．000）。随大鼠日龄的增加,视网膜厚度、INL厚度及ONL至RPE层厚度均呈递减趋势。测量视网膜组织切片各对应层次厚度,并与OCT测量结果进行线性回归分析,结果表明两种方法测量的视网膜厚度、INL厚度以及ONL至RPE层厚度均呈正相关（r=0．794,P=0．000;r=0．784,P=0．000;r=0．681,P=0．000）。结论CirrusHD—OCT可以清晰地显示并测量大鼠视网膜各主要层次,且与组织学测量具有较好的相关性。视觉发育关键期内大鼠视网膜逐渐变薄,OCT测量主要表现为INL厚度和ONL至RPE层厚度减少。     

Megahertz ultra-wide-field swept-source retina optical coherence tomography compared to current existing imaging devices

Background

To investigate the image quality of wide-angle cross-sectional and reconstructed fundus images based on ultra-megahertz swept-source Fourier domain mode locking (FDML) OCT compared to current generation diagnostic devices.

Methods

A 1,050 nm swept-source FDML OCT system was constructed running at 1.68 MHz A-scan rate covering approximately 70° field of view. Twelve normal eyes were imaged with the device applying an isotropically dense sampling protocol (1,900?×?1,900 A-scans) with a fill factor of 100 %. Obtained OCT scan image quality was compared with two commercial OCT systems (Heidelberg Spectralis and Stratus OCT) of the same 12 eyes. Reconstructed en-face fundus images from the same FDML-OCT data set were compared to color fundus, infrared and ultra-wide-field scanning laser images (SLO).

Results

Comparison of cross-sectional scans showed a high overall image quality of the 15× averaged FDML images at 1.68 MHz [overall quality grading score: 8.42?±?0.52, range 0 (bad)—10 (excellent)] comparable to current spectral-domain OCTs (overall quality grading score: 8.83?±?0.39, p?=?0.731). On FDML OCT, a dense 3D data set was obtained covering also the central and mid-peripheral retina. The reconstructed FDML OCT en-face fundus images had high image quality comparable to scanning laser ophthalmoscope (SLO) as judged from retinal structures such as vessels and optic disc. Overall grading score was 8.36?±?0.51 for FDML OCT vs 8.27?±?0.65 for SLO (p?=?0.717).

Conclusions

Ultra-wide-field megahertz 3D FDML OCT at 1.68 MHz is feasible, and provides cross-sectional image quality comparable to current spectral-domain OCT devices. In addition, reconstructed en-face visualization of fundus images result in a wide-field view with high image quality as compared to currently available fundus imaging devices. The improvement of >30× in imaging speed over commercial spectral-domain OCT technology enables high-density scan protocols leading to a data set for high quality cross-sectional and en-face images of the posterior segment.     

Single-shot dimension measurements of the mouse eye using SD-OCT

The authors demonstrate the feasibility and advantage of spectral-domain optical coherence tomography (SD-OCT) for single-shot ocular biometric measurement during the development of the mouse eye. A high-resolution SD-OCT system was built for single-shot imaging of the whole mouse eye in vivo. The axial resolution and imaging depth of the system are 4.5 μm (in tissue) and 5.2 mm, respectively. The system is capable of acquiring a cross-sectional OCT image consisting of 2,048 depth scans in 85 ms. The imaging capability of the SD-OCT system was validated by imaging the normal ocular growth and experimental myopia model using C57BL/6J mice. The biometric dimensions of the mouse eye can be calculated directly from one snapshot of the SD-OCT image. The biometric parameters of the mouse eye including axial length, corneal thickness, anterior chamber depth, lens thickness, vitreous chamber depth, and retinal thickness were successfully measured by the SD-OCT. In the normal ocular growth group, the axial length increased significantly from 28 to 82 days of age (P < .001). The lens thickness increased and the vitreous chamber depth decreased significantly during this period (P < .001 and P = .001, respectively). In the experimental myopia group, there were significant increases in vitreous chamber depth and axial length in comparison to the control eyes (P = .040 and P < .001, respectively). SD-OCT is capable of providing single-shot direct, fast, and high-resolution measurements of the dimensions of young and adult mouse eyes. As a result, SD-OCT is a potentially powerful tool that can be easily applied to research in eye development and myopia using small animal models.     

妊娠高血压综合征患者共焦激光扫描炫彩眼底成像和光相干断层扫描图像特征

目的观察妊娠高血压综合征(PIHS)患者共焦激光扫描炫彩眼底成像(MSLI)和OCT图像特征。方法2016年5月至2017年5月于天津市第一中心医院产科确诊的PIHS患者112例224只眼纳入研究。患者平均年龄(27.00±2.14)岁。平均PIHS病程(15.00±8.27)d。自觉有视物模糊、眼花、视觉疲劳87例174只眼。均行BCVA、直接检眼镜、B型超声、共焦激光扫描检眼镜(cSLO)、频域OCT(SD-OCT)检查。采用德国Heidelberg公司Spectralis HRA+OCT仪行SD-OCT检查,采集断层扫描图像。应用基于cSLO的海德堡炫彩程序,按照标准方法进行操作,1次扫描同时获得基于488 nm的蓝光反射、515 nm绿光反射、820 nm红外反射成像,合成MSLI像。将眼底异常表现分为动脉痉挛期(Ⅰ期)、动脉硬化期(Ⅱ期)、视网膜病变期(Ⅲ期)。根据视网膜形态、厚度等有无异常分为表现正常和异常。结果224只眼中,直接检眼镜检查眼底表现正常68只眼(30.36%);眼底表现异常156只眼(69.64%)。其中,Ⅰ期28只眼(17.95%);Ⅱ期40只眼(25.64%);Ⅲ期88只眼(56.41%)。SD-OCT检查,眼底表现正常36只眼(16.07%);表现异常188只眼(83.93%)。眼底表现异常的188只眼中,视网膜神经上皮层浆液性脱离86只眼(45.74%);RPE层脱离56只眼(29.79%);视盘水肿、隆起及视网膜神经纤维层局部反射增强和(或)厚度增加等46只眼(24.47%)。MSLI像中,眼底表现正常48只眼(21.43%);表现异常176只眼(78.57%)。视网膜水肿、浆液性视网膜神经上皮层和RPE层脱离、视网膜神经纤维层增厚等伴有视网膜局部凸起结构改变在MSLI上以绿色呈现。凸起程度越高,颜色越深。与SD-OCT检查显示的视网膜水肿范围一致。结论PIHS患者MSLI与SD-OCT图像显示的病变高度一致;MSLI可更清晰显示视网膜浅层及深层病变。     

Simultaneous fundus imaging and optical coherence tomography of the mouse retina

PURPOSE: To develop a retinal imaging system suitable for routine examination or screening of mouse models and to demonstrate the feasibility of simultaneously acquiring fundus and optical coherence tomography (OCT) images. METHODS: The imaging system is composed of a photographic slit lamp for biomicroscopic examination of the fundus, an OCT interferometer, an OCT beam delivery system designed for the mouse eye, and a mouse positioning stage. Image acquisition was controlled with software that displays the fundus and OCT images in real time, and allows the user to control the position of the OCT beam spot on the fundus image display. The anesthetized mouse was placed in a cylindrical holder on the positioning stage, and a single operator adjusted the position of mouse. RESULTS: Fundus images and OCT scans were successfully acquired in both eyes of 8 C57BL/6 mice. Once the animal is anesthetized and placed in the holder, a typical imaging experiment takes less than 2 minutes. The retinal vasculature, pigmentation, nerve fiber arrangement, and optic nerve head were clearly visible on the fundus images. The quality of the OCT images was sufficient to allow measurement of the total, inner, and outer retinal thicknesses and to visualize the optic nerve head excavation. CONCLUSIONS: The study demonstrates the feasibility of acquiring simultaneous fundus and OCT images of the mouse retina, by a single operator, in a manner suitable for routine evaluation of mouse models of retinal disease.     

Optical coherent tomography features of malattia leventinese

PURPOSE: Malattia leventinese (ML) is an inherited macular degeneration characterized by the presence of large paracentral and small radial drusen. Our purpose was to describe optical coherent tomography (OCT) features observed in ML. DESIGN: Prospective observational case series. METHODS: Ten eyes from five patients with ML aged 27 to 44 years were prospectively included. Best-corrected visual acuity, fundus color photography of the retina, and OCT were performed in each patient. RESULTS: OCT revealed a hyperreflective thickening of the retinal pigment epithelium-Bruch membrane complex, associated with localized dome-shaped elevations. Retinal thickness above the drusen ranged from 221 to 292 microm (mean 260 microm). Foveal thickness ranged from 72 to 200 microm (mean 144 microm) CONCLUSIONS: The large paracentral drusen presented either as a thickening of the retinal pigment epithelium-Bruch complex or as local limited elevation of retinal pigment epithelium-Bruch complex, both associated with preservation of the neurosensory retina.     

Clinical applications of optical coherence tomography for the diagnosis and management of macular diseases

Optical coherence tomography provides high-resolution cross-sectional images of macular pathology in vivo. Owing to its noninvasive noncontact nature and use of near-infrared illumination of the fundus, it is well tolerated by patients. The images can be obtained without dilation and are highly reproducible,quantifying retinal thickness with an axial resolution of 10 microm. These qualities make OCT a powerful diagnostic tool complementary to fluorescein angiography, photography, and biomicroscopy.Optical coherence tomography has proved to be particularly useful for the clinical evaluation of vitreoretinal interface disorders and alterations of the structural anatomy of the macula, such as from edema, choroidal neovascularization, and detachment of the neurosensory retina or RPE. The information obtained from high-resolution evaluation of retinal anatomy allows the diagnosis of conditions that are difficult to establish with biomicroscopy or angiography and improves the clinician's ability to make the optimal treatment decision. The quantitative assessment of OCT allows an objective means to monitor disease progression and therapeutic response.A logical application of this technology is the evaluation of underlying macular pathology in patients considering cataract extraction. Uncovering vitreomacular traction, epiretinal membranes, occult choroidal neovascular membranes with minimal CME, subretinal fluid accumulation, and RPE detachments greatly impacts the clinical management of cataract patients and the weighing of surgical risks and benefits. OCT is a uniquely powerful means of visualizing retinal morphology and pathology that may not be revealed using current techniques of biomicroscopy, fluorescein angiography, or B-scan ultrasonography, and serves as the newest adjunct in diagnostic technology.     

Optical coherence tomography after photodynamic therapy for patients with pathologic myopia

PURPOSE: To evaluate early changes after photodynamic therapy (PDT) for patients with subfoveal choroidal neovascularization (CNV) due to pathologic myopia by optical coherence tomography (OCT). METHODS: PDT was performed on 10 eyes of 10 patients who presented with subfoveal CNV due to pathologic myopia. OCT was used to evaluate changes 1 day, 3 days, and 7 days after therapy. Changes in intraretinal and subretinal fluid and CNV were examined on the images obtained. The retinal elevation and the height of the neurosensory retinal detachment were calculated. From these two values, the thickness of the neurosensory retina was obtained. The thickness of the neurosensory retina was measured to ascertain the intraretinal fluid change, and the height of the neurosensory retinal detachment was measured to ascertain the subretinal fluid change. RESULTS: The mean pretherapy retinal elevation+/-SD increased from 211+/-28 microm to 230+/-39 microm 1 day after PDT and decreased to 221+/-36 microm 3 days after therapy. At 7 days after therapy, the mean retinal elevation+/-SD was 211+/-22 microm. The retinal elevation was due to a subretinal fluid accumulation, whereas the thickness of the neurosensory retina increased only to a minor extent (range, 0-22 microm) and the foveal architecture remained unchanged. The mean pretherapy height+/-SD of the neurosensory retinal detachment was 6+/-11 microm. It was 18+/-20 microm, 12+/-12 microm, and 3+/-6 microm 1 day, 3 days, and 7 days after therapy, respectively. No change in CNV was observed during follow-up. CONCLUSION: The results of our study indicate that the acute infiltration observed in patients with pathologic myopia after PDT occurs in the first day and regresses during the first week. Yet, it should be noted that, unlike in patients with age-related macular degeneration, the acute infiltration phase can be observed by OCT only to a limited extent.     

Quantification of photoreceptor layer thickness in normal eyes using optical coherence tomography

OBJECTIVE: To demonstrate the ability to segment and analyze individual intraretinal layers, including the outer retinal complex (ORC; outer nuclear layer and inner and outer segments of the photoreceptor cells), in healthy eyes using images acquired from the latest commercially available optical coherence tomography (OCT) system (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA) and from the ultrahigh resolution OCT (UHR-OCT) prototype. METHODS: Thirty-seven eyes from 37 healthy subjects underwent complete ophthalmologic examination using StratusOCT and UHR-OCT. ORC was identified and measured using a segmentation algorithm. RESULTS: For StratusOCT, mean weighted ORC thickness +/- SD was 91.1 +/- 7.9 microm, and mean weighted total retinal thickness +/- SD was determined to be 258.9 +/- 10.1 microm. For UHR-OCT, mean weighted ORC thickness +/- SD was 96.4 +/- 6.3 microm, and mean weighted total retinal thickness +/- SD was determined to be 263.4 +/- 9.2 mum. There was a higher rate of algorithm failure with UHR-OCT images. CONCLUSIONS: Photoreceptor layer thickness can be calculated by measuring ORC on OCT images using a macular segmentation algorithm. ORC values may serve as a useful objective parameter in determining the efficacy of various therapeutic modalities that target the photoreceptor layer in various diseases.