The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

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Present and Future of Surface-Enhanced Raman Scattering

The study group.

Objective: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. Design: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Settings Research laboratory. Participants: Convenience sample of normal human subjects. Main Outcome Measures: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. Results: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10- μm depth resolution. Conclusion: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Optical Coherence Tomography of the Human Retina

Importance The retinal vasculature is involved in many ocular diseases that cause visual loss. Although fluorescein angiography is the criterion standard for evaluating the retina vasculature, it has risks of adverse effects and known defects in imaging all the layers of the retinal vasculature. Optical coherence tomography (OCT) angiography can image vessels based on flow characteristics and may provide improved information. Objective To investigate the ability of OCT angiography to image the vascular layers within the retina compared with conventional fluorescein angiography. Design, Setting, and Participants In this study, performed from March 14, 2014, through June 24, 2014, a total of 5 consecutive, overlapping B-scan OCT angiography images composed of 216 A-scans were obtained at 216 discrete positions within a region of interest, typically a 2 × 2-mm area of the retina. The flow imaging was based on split-spectrum amplitude decorrelation angiography (SSADA), which can dissect layers of vessels in the retina. These distinct layers were compared with the fluorescein angiograms in 12 healthy eyes from patients at a private practice retina clinic to evaluate the ability to visualize the radial peripapillary capillary network. The proportion of the inner vs outer retinal vascular layers was estimated by 3 masked readers and compared with conventional fluorescein angiograms of the same eyes. Main Outcomes and Measures Outcome measures were visualization of the radial peripapillary capillary network in the fluorescein and SSADA scans and the proportion of the inner retinal vascular plexus vs the outer retinal capillary plexus as seen in SSADA scans that would match the fluorescein angiogram. Results In none of the 12 eyes could the radial peripapillary capillary network be visualized completely around the nerve head by fluorescein angiography, whereas the network was readily visualized in the SSADA scans. The fluorescein angiograms were matched, with a mean proportion of the inner vascular plexus being 95.3% (95% CI, 92.2%-97.8%) vs 4.7% (95% CI, 2.6%-5.7%) for the outer capillary plexus from the SSADA scans. Conclusions and Relevance Fluorescein angiography does not image the radial peripapillary or the deep capillary networks well. However, OCT angiography can image all layers of the retinal vasculature without dye injection. Therefore, OCT angiography, and the findings generated, have the potential to affect clinical evaluation of the retina in healthy patients and patients with disease.

https://jamanetwork.com/journals/jamaophthalmology/articlepdf/1910581/eoi140088.pdf

Retinal Vascular Layers Imaged by Fluorescein Angiography and Optical Coherence Tomography Angiography

The diffraction tomography theorem is adapted to one-dimensional length measurement. The resulting spectral interferometry technique is described and the first length measurements using this technique on a model eye and on a human eye in vivo are presented.

Measurement of intraocular distances by backscattering spectral interferometry

PART I: TECHNOLOGY AND INTERPRETATION Section 1: Methods and Techniques of OCT Angiography Examination * Principles of Optical Coherence Tomography Angiography * Interpretation of Optical Coherence Tomography Angiography * Optical Coherence Tomography Angiography: Terminology * Techniques for Using OCT Angiography for Clinical Examination * Clinical Applications of OCT SSADA Angiography in Everyday Clinical Practice Section 2: OCT Angiography Examination of Structure and Histology * Retinal Normal Vascularization PART II: OCT ANGIOGRAPHY STUDY OF DISEASES AND DISORDERS Section 3: Anterior Segment OCT Angiography Examination * Corneal and Anterior Segment OCT Angiography Section 4: Retina OCT Angiography Examination: Age-related Macular Degenerations * OCT Angiography Examination of Choroidal Neovascular Membrane in Exudative Age-Related Macular Degeneration * OCT Angiography Examination of Choroidal Neovascular Membrane in Other Disorders * OCT Angiography Follow-up of Choroidal Neovascularization After Treatment * Non-Neovascular Age-related Macular Degeneration Section 5: Retina OCT Angiography Examination: Other Macular Diseases * OCT Angiography Findings in Central Serous Chorioretinopathy * OCT Angiography Examination of Type 2 Idiopathic Macular Telangiectasia * OCT Angiography of Vascular Occlusions * Diabetic Retinopathy * OCT Angiography in Diabetic Retinopathy * OCT Angiography Examination of Foveal Avascular Zone Section 6: Myopia and Pathologic Myopia * OCT Angiography Examination in High Myopia Section 7: Choroid * OCT Angiography Examination of Choroidal Nevi and Melanomas Section 8: Glaucoma and Optic Nerve * OCT Angiography Examination in Glaucoma PART III: FUTURE DEVELOPMENTS IN OCT ANGIOGRAPHY Section 9: Future Developments in OCT Angiography Examination * Ultrahigh Speed Swept Source Technology for OCT Angiography Index

Clinical OCT Angiography Atlas

Aim To assess total retinal blood flow (TRBF) in diabetic retinopathy (DR) using multiplane en face Doppler optical coherence tomography (OCT). Methods A 70 kHz spectral-domain OCT system scanned a 2×2 mm area centred at the optic disc of the eyes with DR and healthy participants. The multiplane en face Doppler OCT algorithm generated a three-dimensional volumetric data set consisting of 195 en face planes. The TRBF was calculated from the maximum flow values of each branching retinal vein at an optimised en face plane. DR severity was graded according to the international clinical classification system. The generalised linear model method was used to compare flow values between DR groups and the control group. Results A total of 71 eyes from 71 participants were included. Ten eyes were excluded due to poor image quality. The within-visit repeatability of scans was 4.1% (coefficient of variation). There was no significant difference in the TRBF between the healthy (46.7±10.2 µL/min) and mild/moderate non-proliferative DR (44.9±12.6 µL/min) groups. The TRBF in severe non-proliferative DR (39.1±12.6 µL/min) and proliferative DR (28.9±8.85 µL/min) groups were significantly lower ( p =0.04 and p p Conclusion The novel multiplane en face Doppler OCT method provided reliable measurements of TRBF in DR eyes. This may be a useful tool in understanding the pathophysiology of DR.

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Assessing total retinal blood flow in diabetic retinopathy using multiplane en face Doppler optical coherence tomography.

Methods of applying OCT angiography are disclosed. In particular, methods of detecting, visualizing and measuring the extent of retinal neovascularization are disclosed. Further disclosed are methods measuring retinal nonperfusion area and choriocapillaris defect area.

Optical coherence tomography angiography methods

Methods and systems for detecting a gold nanorod (GNR) contrast agent in an optical coherence tomography (OCT) image of a sample are disclosed. In one example approach, a method comprises separating the OCT image at the location into short and long wavelength halves around a center wavelength of the OCT system, calculating a ratio between the short and long wavelength halves, and indicating a gold nanorod contrast agent at the location based on the ratio. In some examples, spectral fractionation may be employed to further divide the short and long wavelength halves into sub-bands to increase spectral contrast, reduce noise, and increase accuracy in detecting GNR in a sample.

Spectral fractionation detection of gold nanorod contrast agents using optical coherence tomography

Detection of reduced retinal vessel density in eyes with geographic atrophy secondary to age-related macular degeneration using projection-resolved optical coherence tomography angiography

Yali Jia

Papers

Clinical OCT Angiography Atlas

Assessing total retinal blood flow in diabetic retinopathy using multiplane en face Doppler optical coherence tomography.

Optical coherence tomography angiography methods

Spectral fractionation detection of gold nanorod contrast agents using optical coherence tomography

Detection of reduced retinal vessel density in eyes with geographic atrophy secondary to age-related macular degeneration using projection-resolved optical coherence tomography angiography