The purpose of this study was to evaluate differences in optical coherence tomography angiography (OCTA) metrics in the superficial (SCP), intermediate (ICP), and deep (DCP) vascular plexuses across ...diabetic retinopathy (DR) severity levels.
This was a cross sectional observational retrospective chart review study. Eligible patients with diabetes who underwent same day RTVue XR Avanti OCTA, spectral-domain optical coherence tomography (SD-OCT), and 200-degree Optos ultrawide field color imaging. SCP, ICP, and DCP vessel density (VD) and vessel length density (VLD) were assessed using 3-D projection artifact removal software (PAROCTA) software.
Of 396 eyes (237 patients), 16.1% had no DR, 26.9% mild nonproliferative DR (NPDR), 21.1% moderate NPDR, 12.1% severe NPDR, 10.1% proliferative DR (PDR) without panretinal photocoagulation (PRP), and 13.4% PDR with PRP. When comparing mild NPDR to no DR eyes, ICP and DCP VD and VLD were significantly lower, but there was no difference for SCP metrics. In eyes with more severe DR, there were significant differences in SCP VD and VLD between DR severity levels (mild versus moderate NPDR: VD 35.45 ± 3.31 vs. 34.14 ± 3.38, P = 0.008 and VLD 17.59 ± 1.83 vs. 16.80 ± 1.83, P = 0.003; moderate versus severe NPDR: VLD 16.80 ± 1.83 vs. 15.79 ± 1.84, P = 0.019), but no significant differences in ICP or DCP.
Although VD of each of the three individual layers decreases with increasing DR severity, DR severity has a substantially different effect on OCTA parameters within each layer. Vascular changes in eyes with no to early DR were present primarily in the deeper vascular layers, whereas in eyes with advanced DR the opposite was observed. This study highlights the effects of ICP and the importance of assessing SCP and DCP changes independently across each DR severity level.
Diabetic retinopathy (DR) is a leading cause of vision loss worldwide. Microaneurysms (MAs), which are abnormal outpouchings of the retinal vessels, are early and hallmark lesions of DR. The presence ...and severity of MAs are utilized to determine overall DR severity. In addition, MAs can directly contribute to retinal neural pathology by leaking fluid into the surrounding retina, causing abnormal central retinal thickening and thereby frequently leading to vision loss. Vascular perfusion parameters such as shear rate (SR) or wall shear stress (WSS) have been linked to blood clotting and endothelial cell dysfunction, respectively in non-retinal vasculature. However, despite the importance of MAs as a key aspect of diabetic retinal pathology, much remains unknown as to how structural characteristics of individual MAs are associated with these perfusion attributes. MA structural information obtained on high resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) was utilized to estimate perfusion parameters through Computational Fluid Dynamics (CFD) analysis of the AOSLO images. The HemeLB flow solver was used to simulate steady-state and time-dependent fluid flow using both commodity hospital-based and high performance computing resources, depending on the degree of detail required in the simulations. Our results indicate that WSS is lowest in MA regions furthest away from the feeding vessels. Furthermore, areas of low SR are associated with clot location in saccular MAs. These findings suggest that morphology and CFD estimation of perfusion parameters may be useful tools for determining the likelihood of clot presence in individual diabetic MAs.
Ultrahigh resolution spectral domain-OCT (UHR SD-OCT) enables in vivo visualization of micrometric structural markers which differentially associate with normal aging versus age-related macular ...degeneration (AMD). This study explores the hypothesis that UHR SD-OCT can detect and quantify sub-retinal pigment epithelium (RPE) deposits in early AMD, separating AMD pathology from normal aging.
Prospective cross-sectional study.
A total of 53 nonexudative (dry) AMD eyes from 39 patients, and 63 normal eyes from 39 subjects.
Clinical UHR SD-OCT scans were performed using a high-density protocol. Exemplary high-resolution histology and transmission electron microscopy images were obtained from archive donor eyes. Three trained readers evaluated and labeled outer retina morphological features, including the appearance of a hyporeflective split within the RPE–RPE basal lamina (RPE-BL)–Bruch’s membrane (BrM) complex on UHR brightness (B)-scans. A semi-automatic segmentation algorithm measured the thickness of the RPE-BL-BrM split/hyporeflective band.
Qualitative description of outer retinal morphological changes on UHR SD-OCT B-scans; the proportion of the RPE-BL-BrM complex with visible split (%) and the thickness of the resulting hyporeflective band (μm).
In young normal eyes, UHR SD-OCT consistently revealed an RPE-BL-BrM split/hyporeflective band. Its visibility and thickness were less in eyes of advanced age. However, the split/hyporeflective band was again visible in early AMD eyes. Both qualitative reading and quantitative thickness measurements showed significantly elevated visibility and thickness of the RPE-BL-BrM split/hyporeflective in early AMD eyes compared to age-matched controls.
Our imaging results strongly support the hypothesis that appearance of the RPE-BL-BrM split/hyporeflective band in older subjects is dominated by the BL deposit, an indicator of early AMD well known from histology. Ultrahigh resolution SD-OCT can be used to investigate physiological aging as well as early AMD pathology in clinical imaging studies. Developing quantifiable markers associated with disease pathogenesis and progression can facilitate drug discovery, as well as reduce clinical trial times.
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Background
This study aimed to develop a deep learning (DL) algorithm that enhances the quality of a single-frame enface OCTA scan to make it comparable to 4-frame averaged scan without the ...need for the repeated acquisitions required for averaging.
Methods
Each of the healthy eyes and eyes from diabetic subjects that were prospectively enrolled in this cross-sectional study underwent four repeated 6 × 6 mm macular scans (PLEX Elite 9000 SS-OCT), and the repeated scans of each eye were co-registered to produce 4-frame averages. This prospective dataset of original (single-frame) enface scans and their corresponding averaged scans was divided into a training dataset and a validation dataset. In the training dataset, a DL algorithm (named pseudoaveraging) was trained using original scans as input and 4-frame averages as target. In the validation dataset, the pseudoaveraging algorithm was applied to single-frame scans to produce pseudoaveraged scans, and the single-frame and its corresponding averaged and pseudoaveraged scans were all qualitatively compared. In a separate retrospectively collected dataset of single-frame scans from eyes of diabetic subjects, the DL algorithm was applied, and the produced pseudoaveraged scan was qualitatively compared against its corresponding original.
Results
This study included 39 eyes that comprised the prospective dataset (split into 5 eyes for training and 34 eyes for validating the DL algorithm), and 105 eyes that comprised the retrospective test dataset. Of the total 144 study eyes, 58% had any level of diabetic retinopathy (with and without diabetic macular edema), and the rest were from healthy eyes or eyes of diabetic subjects but without diabetic retinopathy and without macular edema. Grading results in the validation dataset showed that the pseudoaveraged enface scan ranked best in overall scan quality, background noise reduction, and visibility of microaneurysms (
p
< 0.05). Averaged scan ranked best for motion artifact reduction (
p
< 0.05). Grading results in the test dataset showed that pseudoaveraging resulted in enhanced small vessels, reduction of background noise, and motion artifact in 100%, 82%, and 98% of scans, respectively. Rates of false-positive/-negative perfusion were zero.
Conclusion
Pseudoaveraging is a feasible DL approach to more efficiently improve enface OCTA scan quality without introducing notable image artifacts.
Myopic glaucoma suspects, particularly with high myopia, experience thinning of nontemporal parameters of retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL), without ...change in optic nerve head (ONH) parameters.
The aim was to assess the effect of myopia on RNFL, GCIPL, and ONH parameters in glaucoma suspects.
Seventy-six eyes of glaucoma suspects studied with Cirrus high definition optical coherence tomography were divided into low (n=27), moderate (n=25), and high myopia (n=24) groups. Optical coherence tomography parameters were correlated with spherical equivalent (SE) and evaluated with areas under the receiver operating characteristic curve for quantifying diagnostic ability to differentiate high myopia from nonhigh myopia.
In high myopia, SE was positively correlated with thinning of average, minimum, and nontemporal GCIPL and thinning of average and nontemporal RNFL (P<0.05 for all), but not for inferior RNFL (P=0.28). In moderate myopia, SE was correlated with thinning of inferonasal and minimum GCIPL as well as superior and inferior RNFL (P<0.05 for all). SE was not correlated with ONH parameters in moderate or high myopia (P>0.05). The largest areas under the receiver operating characteristic curve for RNFL and GCIPL parameters were for superior (0.82) and superonasal (0.80) regions, respectively, with comparable diagnostic ability (P=0.74).
High myopia, in particular, is associated with thinning of average RNFL, average and minimum GCIPL, and nontemporal parameters of both RNFL and GCIPL, warranting consideration of refractive status in glaucoma suspects.
Although microaneurysms (MAs) are a hallmark lesion of diabetic retinopathy, it is unclear why some MAs result in local neural retinal pathology while others are benign. To address this issue, ...longitudinal follow-up of MAs with adaptive optics scanning laser ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography (SDOCT) was performed. AOSLO MA images were graded for wall hyperreflectivity (WH), wall deformability (WD), cross-sectional area and perfusion percentage. SDOCT images were graded within a 500μm zone centered on each MA for disorganization of the retinal inner layers (DRIL). Fluorescein angiography evaluated leakage in a subset. A total of 457 MAs of 102 eyes (57 subjects: mean±SD age 44±12 years, DM duration 23#x00B1;10 years, 61% male, 73% type 1 DM) were assessed over 843 visits (154 MAs with ≥1 visit and mean follow-up of 0.52#x00B1;0.35 years). At baseline, MAs with WH were larger (p≤0.0001), less perfused (p≤0.0001), and associated with DRIL (p=0.002). There was a borderline trend for such MAs to leak fluorescein (p=0.05). Over time, MAs with resolved WH had greater likelihood of DRIL improvement. Conversely, MAs that developed WH had more DRIL worsening (p=0.005). WH change vs. stability was associated with decreased perfusion over time (p≤0.0001). At baseline, WD was associated with smaller MAs (p≤0.0001) and increased perfusion (p≤0.0001), but was not related to fluorescein leakage or DRIL. WD resolution and development were associated with decreased and increased perfusion, respectively (p≤0.0001), but not with change in DRIL. These data suggest that whereas WH is a feature of more mature, larger and less perfused MAs associated with local neural pathology, WD may be present in earlier-stage MAs that are smaller and more fully perfused. Future studies will determine whether these parameters can be used to predict changes in MA size, perfusion, leakage or local neural retinal pathology over time.
Disclosure
J.K. Sun: Other Relationship; Self; Novartis Pharmaceuticals Corporation. Research Support; Self; Genentech, Inc., Optovue, Incorporated, Boston Micromachines Corporation, Adaptive Sensory Technology, Kalvista Pharmaceuticals, Inc.. Other Relationship; Self; Novo Nordisk Inc.. O. Abu-Qamar: None. K. Sampani: None. W. Fickweiler: None. L.P. Aiello: Consultant; Self; Novo Nordisk Inc., Sanofi Genzyme. Stock/Shareholder; Self; Kalvista Pharmaceuticals, Inc.. Consultant; Self; Kalvista Pharmaceuticals, Inc..
To assess the full-thickness macular hole (FTMH) size using the choroidal hypertransmission signal on spectral-domain optical coherence tomography and to compare this method to the standard aperture ...measurement of the minimum aperture size at the level of the neurosensory retina.
Cross-sectional study of retrospective data.
Eyes with FTMH imaged on spectral-domain optical coherence tomography were included. Two independent masked graders used the device's built-in caliper tool to measure the FTMH minimum aperture size at the level of the neurosensory retina and the size of the corresponding hypertransmission signal below the level of the retinal pigment epithelium/Bruch membrane complex. To assess the reproducibility of the hypertransmission measurement in tilted scans, two measurements were obtained and compared; the first was traced parallel to the retinal pigment epithelium (parallel hypertransmission), and the second was horizontal to the image frame (horizontal hypertransmission), both using Image J software.
A total of 31 eyes were enrolled. The mean FTMH minimum aperture size was smaller compared with both the choroidal parallel hypertransmission and horizontal hypertransmission measurements (mean ± SD: 335.7 ± 139.5 µm, 376.7 ± 150.6 µm, 375.1 ± 150.0 µm, respectively. P < 0.001 for both comparisons).
The proposed hypertransmission measurement is a feasible and reproducible alternative to assess FTMH size and could provide the basis for an automated FTMH measurement on cross-sectional spectral-domain optical coherence tomography scans, as presented in this study, or on the spectral-domain optical coherence tomography volumetric data set by using an en face projection.
The purpose of this article is to demonstrate the optical coherence tomography angiography (OCTA) Analysis Toolkit (OAT), a custom-designed software package, as a repeatable and reproducible tool for ...computing OCTA metrics across different devices.
Fourteen participants were imaged using three devices. Foveal avascular zone, vessel index, vessel length index, and vessel diameter index were calculated using the OAT. Repeatability and reproducibility were assessed using the coefficient of variation and interclass correlation coefficient (ICC).
Analysis of identical images demonstrated perfect levels of repeatability for all metrics (coefficient of variation 0%), which was a consequence of the software being deterministic (ie, producing the same outputs for the same inputs). Foveal avascular zone ICC values were in the excellent-to-good range (I
> 0.6) for all devices. All values for vessel index (VI), vessel length index, and vessel diameter index fell in the good-to-fair (I
> 0.4) or excellent-to-good range, except for vessel index analysis in the Cirrus device (I
= 0.34).
The OAT appears to be a reliable tool that may enable comparison between OCTA data sets acquired on different imaging instruments, thereby facilitating a more consistent approach to OCTA analysis.
.
The purpose of this study was to assess how projection artifact removal (PAR) alters optical coherence tomography angiography (OCTA) assessment of superficial capillary plexus (SCP) and deep ...capillary plexus (DCP) in eyes of patients with diabetes.
We acquired 3 × 3 mm scans with RTVue-XR Avanti (Optovue, Inc., Fremont, CA), which were analyzed with PAR software (PAROCTA) and without (non-PAROCTA). SCP, DCP, and full thickness retina vascular density (VD) and vessel linear density (VLD) were manually calculated using ImageJ (version 1.51). Adjusted flow index (AFI) was manually assessed for full thickness images.
Among 323 eyes of 194 patients (no diabetic retinopathy DR: 28 eyes; mild nonproliferative DR (NPDR): 96 eyes; moderate: 82 eyes; severe: 32 eyes; and proliferative DR PDR: 81 eyes), SCP VD and VLD were lower with PAROCTA than with non-PAROCTA only in eyes with moderate (VD:
= 0.017; VLD:
= 0.046), severe (
= 0.016;
= 0.009), and PDR (
< 0.001;
= 0.002). DCP VD and VLD were higher with PAROCTA as compared to non-PAROCTA only in eyes with no DR (VD and VLD:
< 0.001), mild (VD and VLD:
< 0.001), moderate (VD:
= 0.005; and VLD:
< 0.001), and severe (VD:
= 0.009; VLD:
< 0.001). Full thickness PAROCTA and non-PAROCTA VD and VLD differed only in eyes with no DR where PAROCTA estimates were higher (VD:
= 0.009; VLD:
= 0.02). PAROCTA AFI was lower than non-PAROCTA AFI for all DR severity levels (
< 0.001) except no DR.
Although differential effects of PAROCTA software are expected on SCP versus DCP measurements, these findings also suggest an interaction between PAROCTA and DR severity on assessment of VD. Conclusions from previous studies that have not corrected VD with PAR software should be carefully reviewed with regard to the role of specific vascular layers in DR.
Previous OCTA studies that have not corrected VD with PAR software should be carefully reviewed with regard to the role of individual vascular layers in differing severity levels of DR.
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