High-resolution Optical Coherence Tomography Research Articles

Design and optimization of a spectrometer for high-resolution SD-OCT

We report the design of a high-efficiency spectrometer for high-resolution spectral-domain optical coherence tomography (SD-OCT). The advantages of the proposed spectrometer are two-fold: first, we use a concave mirror instead of a camera lens (as typically used) as the focusing optics to both improve the transmission efficiency and eliminate chromatic aberrations; second, the efficiency of the proposed spectrometer is approximately 1.23 times that of a refractive optics-based spectrometer for an SD-OCT system, with comparable ranging depth and axial resolution. Both theoretical analyses and imaging experiments were conducted to characterize and validate the performance of the proposed spectrometer.

Evaluation of outer retinal tubulations in diabetic macular edema underwent anti-VEGF treatment.

To investigate the incidence and subsequent changes of outer retinal tubulations (ORTs) in diabetic macular edema (DME) underwent anti-vascular endothelial growth factor (VEGF) therapy, and to assess the possibility of ORT as a biomarker of DME severity or response to anti-VEGF therapy. This retrospective and descriptive study included a total of 228 patients (435 eyes) with DME and treated with intravitreal anti-VEGF agents between March 2016 and January 2018. Patients were divided into 2 groups according to the presence of ORTs. High-resolution spectral-domain optical coherence tomography (SD-OCT) images acquired by vertical and horizontal scans and over consecutive visits were analyzed. The evolution of ORT over time, type of fluid and subfoveal photoreceptor integrity on OCT imaging was also assessed. ORTs were identified in 108 eyes of 435 eyes with an overall incidence rate of 24.83% at baseline. ORTs were prone to locate adjacent to the lesions of exudation and/or cystoid edema and possibly situated in outer nuclear layer (ONL), outer plexiform layer (OPL) and/or inner nuclear layer (INL) in eyes with DME. The formation process of ORT led to focal downward displacement of OPL and INL toward RPE near the lesion. During the follow up, 45 eyes had steady ORTs and 63 eyes had dynamic variants in ORTs, including disappearance, reappearance, collapse, diminution, and enlargement. There were higher proportion of closed ORTs and fewer proportion of forming ORTs in eyes with steady ORTs, which showed a statistically significance when compared with eyes with variant ORTs (P=0.006, P=0.017, respectively). The eyes without ORTs had significantly better final best corrected visual acuity (BCVA) and more BCVA change than those eyes with ORTs in DME patients after anti-VEGF therapy (P=0.023, P=0.009, respectively). The disruption of subfoveal photoreceptor integrity in eyes with ORTs was more serious than that in eyes without ORTs (P=0.013). The proportion of stable vision in eyes with ORTs was significantly higher than that in eyes without ORTs, showing statistical significance (P=0.016). ORTs were associated with worse visual prognosis due to damage of the subfoveal photoreceptor integrity. ORTs have a high incidence and changes over time in DME with anti-VEGF treatment and may be located at various retinal layers. Persistent ORT can be as a negative biomarker of outcome of DME.

VESSEL PREPARATION IMPROVES DRUG ELUTING STENT (DES) EXPANSION PARAMETERS VERSUS DIRECT CORONARY STENTING IN NON-COMPLEX LESIONS AS ASSESSED BY HIGH-RESOLUTION OPTICAL COHERENCE TOMOGRAPHY (OCT)

DES may be deployed with or without vessel prep in uncalcified CAD. It is unknown if vessel prep improves DES expansion/apposition vs. high-pressure direct stenting and if the architecture of individual DES platforms impacts expansion. High-resolution OCT is an ideal tool for measuring DES sizing/

Theory and design of Schwarzschild scan objective for Optical Coherence Tomography.

Optical coherence elastography (OCE) is one form of multi-channel imaging that combines high-resolution optical coherence tomography (OCT) imaging with mechanical tissue stimulation. This combination of structural and functional imaging can require additional space to integrate imaging capabilities with additional functional elements (e.g., optical, mechanical, or acoustic modulators) either at or near the imaging axis. We address this challenge by designing a novel scan lens based on a modified Schwarzchild objective lens, comprised of a pair of concentric mirrors with potential space to incorporate additional functional elements and minimal compromise to the available scan field. This scan objective design allows perpendicular tissue-excitation and response recording. The optimized scan lens design results in a working distance that is extended to ~140 mm (nearly 2x the focal length), an expanded central space suitable for additional functional elements (>15 mm in diameter) and diffraction-limited lateral resolution (19.33 μm) across a full annular scan field ~ ± 7.5 mm to ± 12.7 mm.

Estimating Retinal Sensitivity Using Optical Coherence Tomography With Deep-Learning Algorithms in Macular Telangiectasia Type 2

As currently used, microperimetry is a burdensome clinical testing modality for testing retinal sensitivity requiring long testing times and trained technicians. To create a deep-learning network that could directly estimate function from structure de novo to provide an en face high-resolution map of estimated retinal sensitivity. A cross-sectional imaging study using data collected between January 1, 2016, and November 30, 2017, from the Natural History Observation and Registry of macular telangiectasia type 2 (MacTel) evaluated 38 participants with confirmed MacTel from 2 centers. Mean absolute error of estimated compared with observed retinal sensitivity. Observed retinal sensitivity was obtained with fundus-controlled perimetry (microperimetry). Estimates of retinal sensitivity were made with deep-learning models that learned on superpositions of high-resolution optical coherence tomography (OCT) scans and microperimetry results. Those predictions were used to create high-density en face sensitivity maps of the macula. Training, validation, and test sets were segregated at the patient level. A total of 2499 microperimetry sensitivities were mapped onto 1708 OCT B-scans from 63 eyes of 38 patients (mean [SD] age, 74.3 [9.7] years; 15 men [39.5%]). The numbers of examples for our algorithm were 67 899 (103 053 after data augmentation) for training, 1695 for validation, and 1212 for testing. Mean absolute error results were 4.51 dB (95% CI, 4.36-4.65 dB) when using linear regression and 3.66 dB (95% CI, 3.53-3.78 dB) when using the LeNet model. Using a 49.9 million-variable deep-learning model, a mean absolute error of 3.36 dB (95% CI, 3.25-3.48 dB) of retinal sensitivity for validation and test was achieved. Correlation showed a high degree of agreement (Pearson correlation r = 0.78). By paired Wilcoxon rank sum test, our model significantly outperformed these 2 baseline models (P < .001). High-resolution en face maps of estimated retinal sensitivities were created in eyes with MacTel. The maps were of unequalled resolution compared with microperimetry and were able to correctly delineate functionally healthy and impaired retina. This model may be useful to monitor structural and functional disease progression and has potential as an objective surrogate outcome measure in investigational trials.

Real-time high-resolution mid-infrared optical coherence tomography

The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4 µm and an axial resolution of 8.6 µm is demonstrated. The system produces two-dimensional cross-sectional images in real time enabled by a high-brightness 0.9- to 4.7-µm mid-infrared supercontinuum source with a pulse repetition rate of 1 MHz for illumination and broadband upconversion of more than 1-µm bandwidth from 3.58–4.63 µm to 820–865 nm, where a standard 800-nm spectrometer can be used for fast detection. The images produced by the mid-infrared system are compared with those delivered by a state-of-the-art ultra-high-resolution near-infrared optical coherence tomography system operating at 1.3 μm, and the potential applications and samples suited for this technology are discussed. In doing so, the first practical mid-infrared optical coherence tomography system is demonstrated, with immediate applications in real-time non-destructive testing for the inspection of defects and thickness measurements in samples that exhibit strong scattering at shorter wavelengths.

Multisectorial changes in the ciliary muscle during accommodation measured with high-resolution optical coherence tomography.

To measure changes in the anterior ciliary muscle during accommodation at the nasal, superior, temporal, and inferior sectors by means of an anterior chamber optical coherence tomographer, and correlate them with vergence changes. Twenty-four subjects with healthy, phakic eyes, whose mean age was 27.1 ± 8.9 years, underwent measurement with an anterior chamber optical coherence tomographer. The anterior ciliary muscle was measured at the nasal, temporal, superior, and inferior sectors for 0, -1, -2, and -3 D of vergence. A linear model was used to assess the correlation of each eye parameter with the accommodative demand. The anterior ciliary muscle area significantly increased with accommodation for each sector, with a maximum increase of about 30% for the nasal-temporal sectors and about 25% for the inferior-temporal sectors. The linear model showed a tendency toward a positive relationship between change in the ciliary muscle area of each sector and vergence. The anterior ciliary muscle area tends to increase with accommodation, although the increase has been shown to be symmetric between the pair sectors superior-nasal and inferior-temporal. These results may help to increase understanding of accommodation biometry and biomechanics.

Spectral-domain optical coherence tomography foveal morphology as a prognostic factor for vision performance in congenital aniridia.

Patients with congenital aniridia usually have some degree of foveal hypoplasia, thus representing a limiting factor in the final visual acuity achieved by these patients. The purpose of this study was to analyze whether the foveal morphology assessed by spectral-domain optical coherence tomography may serve as a prognostic indicator for best-corrected visual acuity in congenital aniridia patients. Observational two-center study performed between January 2012 and March 2017 in the pediatric ophthalmology department at Vissum Alicante and Vissum Madrid, Spain. A total of 31 eyes from 19 patients with congenital aniridia were included. After a complete ophthalmological examination, a high-resolution spectral-domain optical coherence tomography with a three-dimensional scan program macular protocol was used. A morphological grading system of foveal hypoplasia was used varying from grade 1 in which there is a presence of a shallow foveal pit, extrusion of inner retinal layers, outer nuclear layer widening, and a presence of outer segment lengthening to grade 4 in which none of these processes occur. No correlation between central, mid-peripheral, and peripheral macular thickness and logMAR best-corrected visual acuity was found. The presence of outer segment lengthening was associated with better best-corrected visual acuity with a median best-corrected visual acuity, 0.30 logMAR, whereas the absence of this morphologic feature was associated with poorer VA with a median best-corrected visual acuity of 0.61 logMAR (p < 0.001). Foveal hypoplasia morphology can predict the best-corrected visual acuity. Specifically, the morphologic optical coherence tomography feature that is related to a better best-corrected visual acuity in congenital aniridia patients is the presence of outer segment lengthening.

Corneal dystrophies in optical coherence tomography

Corneal optical coherence tomography (anterior segment OCT, AS-OCT) is described in the current IC3D classification of corneal dystrophies to be amethod for improvement of clinical diagnostics and treatment. In this case series AS-OCT images of corneal dystrophies were analyzed with respect to morphological changes. This was aretrospective imaging and morphological case series with 38 eyes. For image acquisition the corneal module of the high-resolution spectral-domain OCT Zeiss Cirrus HD-5000 platform (Oberkochen, Germany) was employed. The following corneal dystrophies were analyzed: epithelial basement membrane dystrophy, Meesmann corneal dystrophy, Reis-Bücklers corneal dystrophy, granular corneal dystrophy type1, granular corneal dystrophy type2 and macular corneal dystrophy. The AS-OCT images showed the typical changes of the dystrophies through hyperreflectivity and hyporeflectivity in the individual corneal layers. The findings in the AS-OCT images correlated well with the histological descriptions in the literature and provided additional information to the slit lamp examination, especially with respect to the exact location of the alterations. Corneal AS-OCT imaging seems to be ahelpful tool for determination of morphological changes in patients with corneal dystrophies and can facilitate both the diagnostics and surgical treatment decisions.

Segmentation of the Four-Layered Retinal Vasculature Using High-Resolution Optical Coherence Tomography Angiography Reveals the Microcirculation Unit.

To differentiate the four layers of the retinal vessel network in the human macula and examine their morphologic features using high-resolution optical coherence tomography angiography (HR-OCTA). Macular areas measuring 464 × 464 pixels of 10 right eyes of 10 healthy subjects without ocular disease were scanned 10 times using a HR-OCTA device. Averaged OCTA images were created. Based on clear decorrelation signals, four vascular slabs were segmented, comprising one each in the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and top and bottom of the inner nuclear layer (INL). Qualitative features and quantitative measurements in each slab were compared with those in conventionally segmented slabs. HR-OCTA isolated four layers of vascular plexuses in the macula that followed the corresponding anatomic layers. Segmentations for the RNFL revealed that radial peripapillary capillaries (RPCs) extended to the central macular area. The RPCs followed relatively straight and long paths, with few apparent feed points and anastomoses. The GCL slab enhanced visualization of the capillary-free zones around the arteries and arterioles and helped to differentiate arterial and venous systems. The arterioles and venules were linked by capillaries that were arranged in a mesh-like fashion, with multiple arteriolar feed points and anastomoses. Vascular plexuses in the top and bottom of the INL consisted of capillaries in a vortex arrangement. The center of these vortex arrangements was consistent with the venules in the GCL. HR-OCTA can differentiate the four layers of vascular plexuses in the human macula and elucidate their angiographic features.

Tear dynamics under scleral lenses.

To evaluate post-lens tear dynamics at two different time points during scleral lens wear in two cohorts with 10 neophytes each. All subjects wore bilaterally scleral lenses for 5 h on 3 separate visits. Post-lens tear exchange was measured using Out-in method, which required 5 μL of 2% FITC-Dextran instilled on the bulbar conjunctiva during lens wear. Time taken to observe the first sign of fluorescence in post-lens tear reservoir was recorded with a stopwatch. Out-in measurements were collected at 5-hour post-lens insertion in Group 1 and compared with those obtained at 20 min of lens wear in Group 2. Tear dynamics under the lens was observed in Group 2 with fluorogram using a modified slit-lamp technique (Tan et al., 2018) to monitor post-lens fluorescence intensity and with high-resolution spectral domain optical coherence tomography (ENVISU 2300; Bioptigen Inc.) to measure post-lens tear thickness (PoLTT) over 5 h of lens wear. 60% of subjects in Group 1 achieved Out-in times less than 5 min at 5-hour post-lens insertion, compared with 67% of subjects at 20-min lens wear (Tan et al., 2018). Using qualitative analysis on 60 series of data in Group 2 to compare the changes in fluorescence intensity and PoLTT with respect to lens-wearing time, 27% was due to lens settling, 13% was due to tear exchange and mixing while 60% indicated tear dynamics under scleral lenses was due to a combination of tear exchange, mixing, and lens settling. Tear flow into tear reservoir under a scleral lens on subjects with healthy cornea occurred at 20 min and 5 h after lens insertion. After 5 h of lens wear, roughly one third of the subjects had no tear flow into post-lens reservoir, as the observed decline in post-lens tear fluorescence was predominately due to lens settling.

250 kHz, 1.5 µm resolution SD-OCT for in-vivo cellular imaging of the human cornea.

We present the first spectral domain optical coherence tomography (SD-OCT) system that combines an isotropic imaging resolution of ~1.5 µm in biological tissue with a 250 kHz image acquisition rate, for in vivo non-contact, volumetric imaging of the cellular structure of the human cornea. OCT images of the healthy human cornea acquired with this system reveal the cellular structure of the corneal epithelium, cellular debris and mucin clusters in the tear film, the shape, size and spatial distribution of the sub-basal corneal nerves and keratocytes in the corneal stroma, as well as reflections from endothelial nuclei. The corneal images presented here demonstrate the potential clinical value of the new high speed, high resolution OCT system for non-invasive diagnostics and monitoring the treatment of corneal diseases.

Combination of High-Resolution Optical Coherence Tomography and Raman Spectroscopy for Improved Staging and Grading in Bladder Cancer

We present a combination of optical coherence tomography (OCT) and Raman spectroscopy (RS) for improved diagnosis and discrimination of different stages and grades of bladder cancer ex vivo by linking the complementary information provided by these two techniques. Bladder samples were obtained from biopsies dissected via transurethral resection of the bladder tumor (TURBT). As OCT provides structural information rapidly, it was used as a red-flag technology to scan the bladder wall for suspicious lesions with the ability to discriminate malignant tissue from healthy urothelium. Upon identification of degenerated tissue via OCT, RS was implemented to determine the molecular characteristics via point measurements at suspicious sites. Combining the complementary information of both modalities allows not only for staging, but also for differentiation of low-grade and high-grade cancer based on a multivariate statistical analysis. OCT was able to clearly differentiate between healthy and malignant tissue by tomogram inspection and achieved an accuracy of 71% in the staging of the tumor, from pTa to pT2, through texture analysis followed by k-nearest neighbor classification. RS yielded an accuracy of 93% in discriminating low-grade from high-grade lesions via principal component analysis followed by k-nearest neighbor classification. In this study, we show the potential of a multi-modal approach with OCT for fast pre-screening and staging of cancerous lesions followed by RS for enhanced discrimination of low-grade and high-grade bladder cancer in a non-destructive, label-free and non-invasive way.

Fully automated dual-resolution serial optical coherence tomography aimed at diffusion MRI validation in whole mouse brains.

.An automated dual-resolution serial optical coherence tomography (2R-SOCT) scanner is developed. The serial histology system combines a low-resolution () OCT with a high-resolution () OCT to acquire whole mouse brains at low resolution and to target specific regions of interest (ROIs) at high resolution. The ROIs positions are selected either manually by the microscope operator or using an automated ROI positioning selection algorithm. Additionally, a multimodal and multiresolution registration pipeline is developed in order to align the 2R-SOCT data onto diffusion MRI (dMRI) data acquired in the same ex vivo mouse brains prior to automated histology. Using this imaging system, 3 whole mouse brains are imaged, and 250 high-resolution three-dimensional ROIs are acquired. The capability of this system to perform multimodal imaging studies is demonstrated by labeling the ROIs using a mouse brain atlas and by categorizing the ROIs based on their associated dMRI measures. This reveals a good correspondence of the tissue microstructure imaged by the high-resolution OCT with various dMRI measures such as fractional anisotropy, number of fiber orientations, apparent fiber density, orientation dispersion, and intracellular volume fraction.

Optic nerve head three-dimensional shape analysis.

We present a method for optic nerve head (ONH) 3-D shape analysis from retinal optical coherence tomography (OCT). The possibility to noninvasively acquire in vivo high-resolution 3-D volumes of the ONH using spectral domain OCT drives the need to develop tools that quantify the shape of this structure and extract information for clinical applications. The presented method automatically generates a 3-D ONH model and then allows the computation of several 3-D parameters describing the ONH. The method starts with a high-resolution OCT volume scan as input. From this scan, the model-defining inner limiting membrane (ILM) as inner surface and the retinal pigment epithelium as outer surface are segmented, and the Bruch's membrane opening (BMO) as the model origin is detected. Based on the generated ONH model by triangulated 3-D surface reconstruction, different parameters (areas, volumes, annular surface ring, minimum distances) of different ONH regions can then be computed. Additionally, the bending energy (roughness) in the BMO region on the ILM surface and 3-D BMO-MRW surface area are computed. We show that our method is reliable and robust across a large variety of ONH topologies (specific to this structure) and present a first clinical application.

Vitrectomy and iOCT-assisted inverted ILM flap technique in patients with full thickness macular holes

In large full thickness macular holes (FTMH) the closure rate after vitrectomy and conventional internal limiting membrane (ILM) peeling is less than 90%. The aim of this study was to examine the visual acuity and anatomical success rate with high-resolution optical coherence tomography (OCT) after transconjunctival sutureless 23-gauge pars plana vitrectomy as well as intraoperative OCT (iOCT) and Brilliant Peel (BP)-assisted ILM peeling using the inverted ILM flap technique in patients with large FTMHs. In this retrospective study 25eyes of 25 consecutive patients with large FTMH were treated by 23-G vitrectomy with BP and iOCT-assisted ILM peeling using the inverted ILM flap technique followed by gas tamponade. In all patients best corrected visual acuity (BCVA) and the maximum diameter, base and height of the FTMH as well as intraretinal alterations were measured preoperatively using high-resolution spectral domain OCT (SD-OCT, Spectralis, Heidelberg Engineering, Germany). The BCVA was measured after 1, 3, and 6months. Additionally, the closure rate and the microstructural integrity of the outer retinal layers, e.g. external limiting membrane (ELM), ellipsoid zone und photoreceptor outer segment (OS) were registered in the SD-OCT and correlated with the results of BCVA after macular hole surgery. In all surgical procedures with the inverted ILM flap technique the application of iOCT enabled agood visualization and acontrolled positioning of the ILM flaps. At baseline mean BCVA was 0.2 (0.7 logMAR) and improved significantly after 1, 3 und 6months to 0.4 (0.4 logMAR), 0.5 (0.3 logMAR) and 0.63 (0.2 logMAR), respectively. The closure rate of the FTMHs was 100%. Microstructural integrity of the outer retinal layers was evaluated semiquantitatively and showed good correlation with BCVA. Vitrectomy with BP and iOCT-assisted ILM peeling using the inverted ILM flap technique in patients with large FTMH is avery controlled and safe microsurgical strategy and shows good functional and anatomical results. The morphology of the FTMH, the ILM flap and the position of the inverted ILM flap under air was well visualized by IOCT. The microstructural integrity of the outer retinal layers is displayed in detail on SD-OCT and represents an important predictive parameter for BCVA after macular hole surgery.

Utility of Optical Coherence Tomography for Guiding Laser Therapy Among Patients With Recurrent Respiratory Papillomatosis

Recurrent respiratory papillomatosis (RRP) is a viral-induced disease caused by human papillomavirus and the second leading cause of dysphonia in children; however, neither a cure nor a definitive surgical treatment is currently available for RRP. Although laser therapy is often used in the treatment of RRP, the lack of real-time laser-tissue interaction feedback undermines the ability of physicians to provide treatments with low morbidity. Therefore, an intraoperative tool to monitor and control laser treatment depth is needed. To investigate the potential of combining optical coherence tomography (OCT) with laser therapy for patient-tailored laryngeal RRP treatments. This in vivo study was performed at the Massachusetts Eye and Ear Infirmary from February 1, 2017, to September 1, 2017. Three-dimensional OCT images were acquired before, during, and after photoangiolytic laser therapy in 10 pediatric patients with a history of papilloma growth who presented with lesions and hoarseness. Whether intraoperative OCT monitoring of changes in optical scattering and absorption provides quantitative information to control thermal damage in tissue. Among the 10 pediatric patients (age range, 4-11 years; 6 male) included in the study, high-resolution OCT images revealed epithelial hyperplasia with clear RRP lesion margins. Images acquired during therapy indicated coagulation deep in tissue, and posttherapy images showed the ability to quantify the amount of tissue ablated by the photoangiolytic laser. Concurrent use of OCT imaging and laser therapy may improve postoperative outcomes for patients with RRP by delivering an optimal, patient-tailored treatment. Additional studies investigating the correlation between optical properties with vocal outcomes are required.

Shields Gray Crescents Masquerading as Glaucomatous Cupping of the Optic Nerve Head

Gray crescents characterized by darkly pigmented regions on the optic nerve head could make assessment of cupping difficult by obscuring the true anatomic disc border. On slit-lamp examination, 2 morphologically distinct types of gray crescents at the curved disc boundary exist. The invivo histologic characteristics differentiating these 2 types are described using spectral-domain (SD) OCT. A prospective interventional case series in a single tertiary referral center. Sixteen eyes of 10 patients with gray crescents determined through clinical examination and fundus photography underwent cross-sectional optic nerve head and parapapillary imaging using high-resolution SD OCT. Invivo histology of gray crescents was characterized. In SD OCT images across the areas of gray crescent, type A gray crescents represent regions where the retinal pigment epithelium (RPE)-Bruch's membrane complex is absent and the dark underlying choroid is directly visible. In contrast, type B gray crescents represent regions of the retina where the RPE is clumped or thickened, typically appearing to be folded upon itself, revealing the embryonic continuity of the RPE and neuroretina. Shields type A and B gray crescents appear different clinically because histologically they represent differences in RPE. Type A grey crescents lack RPE, whereas type B crescents have thickened, folded RPE. Gray crescents can obscure the true disc border and result in pseudo-cupping of the optic nerve head. Identification of gray crescents is clinically important because failure to recognize pseudo-cupping can contribute to overdiagnosis of glaucoma.

QUANTITATIVE ANALYSIS OF THE INNER RETINAL LAYER THICKNESSES IN AGE-RELATED MACULAR DEGENERATION USING CORRECTED OPTICAL COHERENCE TOMOGRAPHY SEGMENTATION.

To characterize inner retinal damage in patients with dry age-related macular degeneration (AMD) using high-resolution spectral domain optical coherence tomography images. Sixty eyes of 60 patients with AMD were categorized using the Age-Related Eye Disease Study (AREDS) severity scale. Spectral domain optical coherence tomography images of these patients were quantified by manually correcting the segmentation of each retinal layer, including the retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer to ensure accurate delineation of layers. The mean ganglion cell complex thickness values (ganglion cell layer + inner plexiform layer + retinal nerve fiber layer) were compared with 30 eyes of 30 healthy subjects. Ninety percent of eyes (81 eyes) required manual correction of segmentation. Compared with healthy subjects, mean ganglion cell complex thicknesses significantly decreased in more advanced dry AMD eyes, and this decrease was predominantly related to a change in inner plexiform layer thickness. There was no significant difference in thickness-related measurements between milder dry AMD (AREDS-2) eyes and healthy eyes (P > 0.05). In patients with dry AMD, automatic optical coherence tomography segmentation algorithms may be erroneous. As the severity of dry AMD increases, the inner plexiform layer layer becomes thinned, suggesting that transsynaptic degeneration may be occurring, as the photoreceptor layer is affected by AMD.

P2271Super high-resolution OCT for endothelial cell visualization in the coronary arteries

P2271Super high-resolution OCT for endothelial cell visualization in the coronary arteries