Wide-field Optical Coherence Tomography Angiography Research Articles

Diurnal Variation in Choroidal Parameters Among Healthy Subjects Using Wide-Field Swept-Source Optical Coherence Tomography Angiography.

The purpose of this study was to evaluate the diurnal variation in choroidal parameters in a wide field area among healthy subjects and to identify correlations between choroidal luminal area and stromal area and various systemic factors. In this cross-sectional study, 42 eyes from 21 healthy participants (mean age = 32.4 ± 8.8 years) were examined using wide-field swept-source optical coherence tomography angiography (WF SS-OCTA, 24 mm × 20 mm). Measurements of choroidal parameters, including choroidal volume (CV), choroidal thickness (CT), choroidal vessel volume (CVV), and choroidal stromal volume (CSV), were taken at 8:00, 12:00, 18:00, and 22:00. Systemic factors, such as blood pressure and heart rate, were concurrently monitored. Our study observed significant diurnal variations in the mean total CV, CT, CVV, and CSV, with minimum measurements around 12:00 (P < 0.001) and peak values at 22:00 (P < 0.001). Furthermore, changes in CV in specific regions were more closely associated with fluctuations in CVV than CSV in the same regions. No significant diurnal variations were found in systolic (P = 0.137) or diastolic blood pressure (P = 0.236), whereas significant variations were observed in the heart rate (P = 0.001). Our study reveals diurnal variations in choroidal parameters and their associations, emphasizing that changes in choroidal volume relate more to the luminal than the stromal area in vessel-rich regions. This enhances our understanding of choroidal-related ocular diseases. Regions with higher choroidal vasculature observed greater choroidal volume changes.

Diagnosis of Glaucoma Based on Few-Shot Learning with Wide-Field Optical Coherence Tomography Angiography.

This study evaluated the utility of incorporating deep learning into the relatively novel imaging technique of wide-field optical coherence tomography angiography (WF-OCTA) for glaucoma diagnosis. To overcome the challenge of limited data associated with this emerging imaging, the application of few-shot learning (FSL) was explored, and the advantages observed during its implementation were examined. A total of 195 eyes, comprising 82 normal controls and 113 patients with glaucoma, were examined in this study. The system was trained using FSL instead of traditional supervised learning. Model training can be presented in two distinct ways. Glaucoma feature detection was performed using ResNet18 as a feature extractor. To implement FSL, the ProtoNet algorithm was utilized to perform task-independent classification. Using this trained model, the performance of WF-OCTA through the FSL technique was evaluated. We trained the WF-OCTA validation method with 10 normal and 10 glaucoma images and subsequently examined the glaucoma detection effectiveness. FSL using the WF-OCTA image achieved an area under the receiver operating characteristic curve (AUC) of 0.93 (95% confidence interval (CI): 0.912-0.954) and an accuracy of 81%. In contrast, supervised learning using WF-OCTA images produced worse results than FSL, with an AUC of 0.80 (95% CI: 0.778-0.823) and an accuracy of 50% (p-values < 0.05). Furthermore, the FSL method using WF-OCTA images demonstrated improvement over the conventional OCT parameter-based results (all p-values < 0.05). This study demonstrated the effectiveness of applying deep learning to WF-OCTA for glaucoma diagnosis, highlighting the potential of WF-OCTA images in glaucoma diagnostics. Additionally, it showed that FSL could overcome the limitations associated with a small dataset and is expected to be applicable in various clinical settings.

Visualizing features with wide-field volumetric OCT angiography.

Optical coherence tomography (OCT) and its extension OCT angiography (OCTA) have become essential clinical imaging modalities due to their ability to provide depth-resolved angiographic and tissue structural information non-invasively and at high resolution. Within a field of view, the anatomic detail available is sufficient to identify several structural and vascular pathologies that are clinically relevant for multiple prevalent blinding diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), and vein occlusions. The main limitation in contemporary OCT devices is that this field of view is limited due to a fundamental trade-off between system resolution/sensitivity, sampling density, and imaging window dimensions. Here, we describe a swept-source OCT device that can capture up to a 12 × 23-mm field of view in a single shot and show that it can identify conventional pathologic features such as non-perfusion areas outside of conventional fields of view. We also show that our approach maintains sensitivity sufficient to visualize novel features, including choriocapillaris morphology beneath the macula and macrophage-like cells at the inner limiting membrane, both of which may have implications for disease.

Assessment of Microvascular Changes After Rhegmatogenous Retinal Detachment Repair Using Wide-Field Swept-Source Optical Coherence Tomography Angiography.

Our objective was to evaluate retinal microvascular changes and visual outcomes following rhegmatogenous retinal detachment (RRD) repair using wide-field swept-source optical coherence tomography angiography (WF SS-OCTA). The study included 116 eyes of 111 patients with macula-off (n = 68) or macula-on (n = 48) RRD treated with a single successful procedure, 79 fellow eyes, and 183 eyes of control patients imaged with WF SS-OCTA (3 ×3, 6 ×6, and 12 ×12 mm images). Mixed-effects multiple linear regression models were used for statistical analysis. Vessel density (VD) and vessel skeletonized density (VSD) of the superficial capillary plexus (3 ×3 mm scans) and full-thickness retina (12 ×12 mm) were significantly reduced in RRD eyes compared to fellow and control eyes. Decreased VSD and VD in all layers (3 ×3 mm and 6 ×6 mm) were significantly associated with greater preoperative extent of retinal detachment (P < 0.05) and poorer postoperative best-corrected visual acuity (BCVA) in RRD eyes (P < 0.05). Macula-off status was associated with increased foveal avascular zone irregularity (12 ×12 mm, P = 0.02). Decreased VD on WF SS-OCTA is associated with poorer postoperative BCVA following RRD repair. [Ophthalmic Surg Lasers Imaging Retina 2024;55:XX-XX.].

Role of optical coherence tomography angiography in the evaluation of peripheral ischemia in retinal vein occlusion

Abstract: In the last decade, optical coherence tomography angiography (OCTA) has become part of the clinical management of retinal vein occlusion (RVO), proving in itself a useful technique for both the prediction of visual acuity (VA) outcomes and the risk of complications. In fact, OCTA has been proven a valid imaging technique in detailed assessment of foveal and parafoveal microvascular status in both acute and chronic RVO. Quantitative OCTA data have shown a significant correlation not only with final VA but also with the extension of peripheral ischemia, which represents a major risk factor for macular edema recurrence and neovascularization onset. Finally, wide-field OCTA represents a promising noninvasive technique for the assessment of peripheral ischemia. The aim of this review is to report the main literature findings about microvascular changes and clinical applications of OCTA in the context of RVO-induced peripheral ischemia.

ZEISS PLEX Elite 9000 Widefield Optical Coherence Tomography Angiography as Screening Method for Early Detection of Retinal Hemangioblastomas in von Hippel-Lindau Disease.

To evaluate early detection of retinal hemangioblastomas (RHs) in von Hippel-Lindau disease (VHLD) with widefield optical coherence tomography angiography (wOCTA) compared to the standard of care in ophthalmologic VHLD screening in a routine clinical setting. We conducted prospective comparisons of three screening methods: wOCTA, standard ophthalmoscopy, and fluorescein angiography (FA), which was performed only in uncertain cases. The numbers of detected RHs were compared among the three screening methods. The underlying causes for the lack of detection were investigated. In 91 eyes (48 patients), 67 RHs were observed (mean, 0.74 ± 1.59 RH per eye). FA was performed in eight eyes. Ophthalmoscopy overlooked 25 of the 35 RHs detected by wOCTA (71.4%) due to the background color of the choroid (n = 5), small tumor size (n = 13), masking by a bright fundus reflex (n = 2), and masking by surrounding retinal scars (n = 5). However, wOCTA missed 29 RHs due to peripheral location (43.3%). The overall detection rates were up to 37% on the basis of ophthalmoscopy alone, up to 52% for wOCTA, and 89% for FA. Within the retinal area covered by wOCTA, the detection rates were up to 46.7% for ophthalmoscopy alone, up to 92.1% for wOCTA, and 73.3% for FA. The overall low detection rate of RHs using wOCTA is almost exclusively caused by its inability to visualize the entire peripheral retina. Therefore, in unclear cases, FA is necessary after ophthalmoscopy. Within the imageable retinal area, wOCTA shows a high detection rate of RHs and therefore may be suitable to improve screening for RHs in VHLD.

Advantages of the Utilization of Wide-Field OCT and Wide-Field OCT Angiography in Clinical Practice

Wide-field (WF) retinal imaging is becoming a standard diagnostic tool for diseases involving the peripheral retina. Technological progress elicited the advent of wide-field optical coherence tomography (WF-OCT) and WF-OCT angiography (WF-OCTA) examinations. This review presents the results of studies that analyzed the implementation of these procedures in clinical practice and refers to them as traditional and ultra-wide-field fluorescein angiography (UWF-FA). A PUBMED search was performed using the terms WF-OCT OR WF-OCTA OR UWF-FA AND the specific clinical entity, and another search for diabetic retinopathy (DR), retinal vein occlusion (RVO), Coats disease, peripheral retinal telangiectasia, peripheral retinal degeneration, lattice degeneration, and posterior vitreous detachment. The analysis only included the studies in which the analyzed field of view for the OCT or OCTA exam was larger than 55 degrees. The evaluation of the extracted studies indicates that WF imaging with OCT and OCTA provides substantial information on retinal disorders involving the peripheral retina. Vascular diseases, such as DR or RVO, can be reliably evaluated using WF-OCTA with results superior to standard-field fluorescein angiography. Nevertheless, UWF-FA provides a larger field of view and still has advantages over WF-OCTA concerning the evaluation of areas of non-perfusion and peripheral neovascularization. Detailed information on the vascular morphology of peripheral changes should be obtained via WF-OCTA and not angiographic examinations. WF-OCT can serve as a valuable tool for the detection and evaluation of vitreoretinal traction, posterior vitreous detachment, and peripheral retinal degeneration, and guide therapeutic decisions on a patient’s eligibility for surgical procedures.

Comparison of Widefield OCT Angiography Features Between Severe Non-Proliferative and Proliferative Diabetic Retinopathy.

There is a high and ever-increasing global prevalence of diabetic retinopathy (DR) and invasive imaging techniques are often required to confirm the presence of proliferative disease. The aim of this study was to explore the images of a rapid and non-invasive technique, widefield optical coherence tomography angiography (OCT-A), to study differences between patients with severe non-proliferative and proliferative DR (PDR). We conducted an observational longitudinal study from November 2022 to March 2023. We recruited 75 patients who were classified into a proliferative group (28 patients) and severe non-proliferative group (47 patients). Classification was done by specialist clinicians who had full access to any multimodal imaging they required to be confident of their diagnosis, including fluorescein angiography. For all patients, we performed single-shot 4 × 4 and 10 × 10mm (widefield) OCT-A imaging and when possible, the multiple images required for mosaic 17.5 × 17.5mm (ultra widefield) OCT-A imaging. We assessed the frequency with which proliferative disease was identifiable solely from these OCT-A images and used custom-built MATLAB software to analyze the images and determine computerized metrics such as density and intensity of vessels, foveal avascular zone, and ischemic areas. On clinically assessing the OCT-A 10 × 10 fields, we were only able to detect new vessels in 25% of known proliferative images. Using ultra-widefield mosaic images, however, we were able to detect new vessels in 100% of PDR patients. The image analysis metrics of 4 × 4 and 10 × 10mm images did not show any significant differences between the two clinical groups. For mosaics, however, there were significant differences in the capillary density in patients with PDR compared to severe non-PDR (9.1% ± 1.9 in the PDR group versus 11.0% ± 1.9 for severe group). We also found with mosaics a significant difference in the metrics of ischemic areas; average area of ischemic zones (253,930.1 ± 108,636 for the proliferative group versus 149,104.2 ± 55,101.8 for the severe group. Our study showed a high sensitivity for detecting PDR using only ultra-widefield mosaic OCT-A imaging, compared to multimodal including fluorescein angiography imaging. It also suggests that image analysis of aspects such as ischemia levels may be useful in identifying higher risk groups as a warning sign for future conversion to neovascularization.

Diagnostic performance of wide-field optical coherence tomography angiography for high myopic glaucoma

Diagnosing and monitoring glaucoma in high myopic (HM) eyes are becoming very important; however, it is challenging to diagnose this condition. This study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (WF-OCTA) maps for the detection of glaucomatous damage in eyes with HM and to compare the diagnostic ability of WF-OCTA maps with that of conventional imaging approaches, including swept-source optical coherence tomography (SS-OCT) wide-field maps. In this retrospective observational study, a total 62 HM-healthy eyes and 140 HM eyes with open-angle glaucoma were included. Patients underwent a comprehensive ocular examination, including SS-OCT wide-field and 12 × 12 WF-OCTA scans. The WF-OCTA map represents the peripapillary and macular superficial vascular density maps. Glaucoma specialists determined the presence of glaucomatous damage in HM eyes by reading the WF-OCTA map and comparing its sensitivity and specificity with those of conventional SS-OCT images. The sensitivity and specificity of 12 × 12 WF-OCTA scans for HM-glaucoma diagnosis were 87.28% and 86.94%, respectively, while, the sensitivity and specificity of SS-OCT wide-field maps for HM-glaucoma diagnosis were 87.49% and 80.51%, respectively. The specificity of the WF-OCTA map was significantly higher than that of the SS-OCT wide-field map (p < 0.05). The sensitivity of the WF-OCTA map was comparable with that of the SS-OCT wide-field map (p = 0.078). The WF-OCTA map showed good diagnostic ability for discriminating HM-glaucomatous eyes from HM-healthy eyes. As a complementary method to an alternative imaging modality, WF-OCTA mapping can be a useful tool for the detection of HM glaucoma.

A CASE OF EALES DISEASE OBSERVED BY WIDEFIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

Purpose: The purpose of this study was to report a 30-year-old woman with Eales disease, showing bilateral proliferative tissue. The retinal vessels were evaluated using widefield optical coherence tomography angiography (widefield OCTA), which has a wider angle of view compared with conventional instruments. Methods: This is a case report. Results: Widefield OCTA showed an extensive nonperfusion area and A-V shunt in both eyes and a vascular structure in the left eye that appeared to be retinal neovascularization. Ultra-widefield fluorescein angiography revealed no filling delay in the early phase, a vast nonperfusion area from the midperiphery to the ora serrata in bilateral eyes, and retinal neovascularization in the left eye. Based on the results of ultra-widefield angiography, OCTA examination, and systemic examination, a diagnosis of Eales disease was finally made after all the differential diseases had been excluded. Conclusion: In a patient with Eales disease, the peripheral nonperfusion area and retinal neovascularization that were consistent with the ultra-widefield angiography findings were noninvasively confirmed by widefield OCTA. Widefield OCTA is useful in the detection of peripheral changes of the fundus.

Diagnostic performance of wide-field optical coherence tomography angiography in detecting open-angle glaucoma in high myopia.

To compare the diagnostic performance of the capillary density (CD) of the central 1-6 mm and peripheral 6-12 mm annular regions in detecting open-angle glaucoma in high myopia (HM) using 15 × 12 mm wide-field swept-source optical coherence tomography angiography (WF SS-OCTA). The study enrolled 206 and 103 eyes with HM and highly myopic open-angle glaucoma (HM-OAG), respectively. WF SS-OCTA images centred on the fovea were obtained to analyse the changes in the CD in the 1-3 mm, 3-6 mm, 6-9 mm, and 9-12 mm annular regions. CD of the superficial capillary plexus (SCP) was measured with the built-in software. The area under the receiver operating characteristic curve (AUROC) of each region was compared. The diagnostic performance of the SCP CD in the central 1-6 mm annular region (AUROC = 0.849) was better than that in the peripheral 6-12 mm annular region (AUROC = 0.756, p = 0.001). The annular AUROCs of SCP CD peaked in the 3-6 mm annular region (AUROC = 0.858) and gradually decreased with increasing diameter and were lower than the corresponding AUROCs of the ganglion cell-inner plexiform layer thickness (p < 0.05 for all comparisons). SCP CD of the inferior quadrant in the 3-6 mm annular region had the best diagnostic performance (AUROC = 0.859). The SCP CD in the central 1-6 mm annular region exhibited better diagnostic performance for the detection of HM-OAG in HM. The assessment of more peripheral regions has no added value in detecting glaucoma in HM.

Practical Utility of Widefield OCT Angiography to Detect Retinal Neovascularization in Eyes with Proliferative Diabetic Retinopathy

To assess the real clinical utility of widefield OCT angiography (WF-OCTA) for detecting retinal neovascularization (RNV) in eyes with proliferative diabetic retinopathy (PDR). A retrospective cross sectional study. Consecutive eyes clinically suspected of PDR by physicians at a tertiary eye center between March 2021 and November2022. All eyes underwent ultrawidefield fluorescein angiography (UWF-FA) (California, Optos) and WF-OCTA (S1, Canon) with a 23× 20 mm scan area. Two independent graders detected individual RNV lesions using UWF-FA and used them as the ground truth. Widefield OCT angiography images were first evaluated to determine whether the images successfully illustrated retinal vasculature, regardless of the image quality index or the presence of vitreous hemorrhage. The graders then identified the RNV lesions with WF-OCTA. We detected RNV by utilizing both the entire retinal slab, including flow signals in the retina, and the custom vitreoretinal interface slab, defined as flow signals from 20 μm below the internal limiting membrane (ILM) to 2000 μm above the ILM. We evaluated the applicability to real clinical practice by not correcting segmentation errors. The success rate of imaging and the detection rate of RNV using WF-OCTA. Initially, 69 consecutive patients who underwent UWF-FA were identified. Of these, 114 eyes from 57 (83%) patients underwent both UWF-FA and WF-OCTA. Of the 114 eyes, 108 (95%) produced gradable WF-OCTA images. Using UWF-FA, the graders identified 175 RNV lesions in 40 eyes. Widefield OCT angiography achieved a sensitivity of 95% and specificity of 88% for detecting eyes with RNV. At the level of individual RNV lesions, graders detected 156 RNV lesions with WF-OCTA, with 118 of these confirmed by UWF-FA (true positive). Among the 57 false-negative lesions, the primary causes were being out of the scan range (26 lesions) and segmentation errors (21 lesions). Widefield OCT angiography imaging had a high success rate, achieving a sensitivity of 95% and a specificity of 88% for detecting eyes with RNV in a real clinical setting. Despite a 67% detection rate for individual RNV lesions, WF-OCTA may serve as a valuable noninvasive method for RNV detection in eyes with diabetic retinopathy. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Widefield swept-source optical coherence tomography angiography metrics associated with neovascular glaucoma in patients with proliferative diabetic retinopathy.

To explore the association between widefield swept-source optical coherence tomography angiography (WF SS-OCTA) metrics, including nonperfusion area (NPA) and neovascularization (NV), and presence of neovascular glaucoma (NVG) in patients with proliferative diabetic retinopathy (PDR). A prospective, cross-sectional study was conducted from November 2018 to February 2020. A total of 85 eyes of 60 PDR patients without NVG and 9 eyes of 8 PDR patients with NVG were included. Retinal ischemic parameters (NPA; ischemia index [NPA/total retinal area]) and NV features (NV number; NV area; NV vessel density) were evaluated. Foveal avascular zone (FAZ), macular thickness/volume, and choroidal thickness/volume were obtained using the Zeiss ARI Network. WF SS-OCTA retinal and choroidal metrics, systemic, and ocular parameters were screened using Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression for variable selection. Firth's bias-reduced logistic regression (outcome: presence of NVG) was subsequently used to identify parameters associated with NVG. After LASSO variable selection, 8 variables were significantly associated with the presence of NVG: DM duration (years), insulin (yes/no), best-corrected visual acuity (BCVA) (logMAR), IOP, ischemia index, skeletonized vessel density, macular thickness (inner inferior, outer temporal regions). Firth's bias-reduced logistic regression showed ischemia index (odds ratio [OR]=13.2, 95% confidence interval [CI]:5.3-30.7, P<0.001) and BCVA (OR=5.8, 95%CI:1.2-28.8, P<0.05) were associated with the presence of NVG. NV metrics, FAZ, and choroidal parameters were not related to NVG. Retinal ischemia but not NV was associated with the presence of NVG in patients with PDR using WF SS-OCTA. Larger, longitudinal studies are needed to validate imaging biomarkers associated with diabetic NVG.

Optical coherence tomography angiography in diabetic retinopathy.

There remain many unanswered questions on how to assess and treat the pathology and complications that arise from diabetic retinopathy (DR). Optical coherence tomography angiography (OCTA) is a novel and non-invasive three-dimensional imaging method that can visualize capillaries in all retinal layers. Numerous studies have confirmed that OCTA can identify early evidence of microvascular changes and provide quantitative assessment of the extent of diseases such as DR and its complications. A number of informative OCTA metrics could be used to assess DR in clinical trials, including measurements of the foveal avascular zone (FAZ; area, acircularity, 3D para-FAZ vessel density), vessel density, extrafoveal avascular zones, and neovascularization. Assessing patients with DR using a full-retinal slab OCTA image can limit segmentation errors and confounding factors such as those related to center-involved diabetic macular edema. Given emerging data suggesting the importance of the peripheral retinal vasculature in assessing and predicting DR progression, wide-field OCTA imaging should also be used. Finally, the use of automated methods and algorithms for OCTA image analysis, such as those that can distinguish between areas of true and false signals, reconstruct images, and produce quantitative metrics, such as FAZ area, will greatly improve the efficiency and standardization of results between studies. Most importantly, clinical trial protocols should account for the relatively high frequency of poor-quality data related to sub-optimal imaging conditions in DR and should incorporate time for assessing OCTA image quality and re-imaging patients where necessary.

Retinal hypoperfusion detected by wide-field optical coherence tomographic angiography in a case of retinal racemose hemangioma.

Retinal racemose hemangioma (RRH) is a rare, non-hereditary arteriovenous malformation characterized by the appearance of dilated and tortuous retinal vessels. RRH can develop complications associated with retinal ischemia, such as vitreous hemorrhage, retinal vein occlusion and neovascular glaucoma. Here, we report a case of RRH with retinal hypoperfusion detected by wide-field swept source optical coherence tomography angiography (OCTA), which was not unambiguously illustrated by fluorescein angiography (FA). Case report. A 57-year-old woman was referred to our hospital for the evaluation of severe retinal vascular tortuosity, dilation and retinal hemorrhages in the left eye. Fundus examination revealed arteriovenous communications temporal to the fovea and multiple microaneurysms surrounded by retinal hemorrhages at the midperipheral temporal fundus. In FA, multiple hyperfluorescent lesions with leakage corresponding to microaneurysms were observed in the temporal and lower midperipheral areas; however, non-perfused areas were apparently absent. By contrast, wide-field OCTA clearly showed low-density retinal capillaries in the superotemporal quadrant in comparison with those in the inferotemporal quadrant. Wide-field OCTA detected sparse retinal capillaries, which were not well illustrated by FA, in a patient with RRH. This indicates the presence of low-grade retinal hypoperfusion caused by altered retinal hemodynamics, potentially leading to ischemia-related retinal disorders during a prolonged course, in patients with clinically quiescent RRH.

Relationship between nonperfusion area from widefield optical coherence tomography angiography and macular vascular parameters in diabetic retinopathy

PurposeTo evaluate the relationship between the nonperfusion area (NPA) from widefield optical coherence tomography angiography (OCTA) and macular vascular parameters in diabetic retinopathy (DR).MethodsIn total, 51 eyes from 51 patients with proliferative DR (PDR) or moderate/severe non-PDR were included. Widefield OCTA using the Zeiss Plex Elite 9000 was performed. A semi-automatic algorithm calculated the percentages of the NPA within the total image. Macular OCTA (3 × 3 mm and 6 × 6 mm area) was scanned using the RTVue-XR Avanti. Vessel density (VD) was automatically separated into the superficial (SCP) and deep capillary plexus (DCP), and foveal avascular zone (FAZ) measurements were computed according to the parafoveal (1–3 mm) and perifoveal (3–6 mm) regions.ResultsA negative correlation was found between the average VD of the SCP and DCP obtained 3 × 3 mm and 6 × 6 mm area and the NPA. Multiple regression analysis revealed that the temporal–perifoveal region most negatively correlated with the NPA (r = − 0.55, p < 0.0001). No correlation was found between FAZ measurements and DR severity (area, p = 0.07; perimeter, p = 0.13).ConclusionDiabetic macular nonperfusion was significantly associated with the NPA from widefield OCTA. In particular, the temporal–perifoveal DCP disorder may be a sensitive indicator of wide NPA.

Inference of Capillary Nonperfusion Progression on Widefield OCT Angiography in Diabetic Retinopathy.

The purpose of this study was to explore the spatial patterns of the nonperfusion areas (NPAs) on widefield optical coherence tomography angiography (OCTA) images in diabetic retinopathy (DR) and to investigate their associations with NPA progression and DR severity. We prospectively enrolled 201 eyes from 158 patients with DR. Widefield images were obtained using a swept-source OCTA device (Xephilio OCT-S1), followed by the creation of 20-mm (1614 pixels) en face images. Nonperfusion squares (NPSs) were defined as 10 × 10-pixel squares without retinal vessels. Eyes with high-dimensional spatial data were mapped onto a two-dimensional space using the uniform manifold approximation and projection algorithm and divided by clustering. The patterns of NPA distribution were statistically compared between clusters. All eyes were mapped onto a two-dimensional space and divided into six clusters based on the similarity of NPA distribution. Eyes in clusters 1 and 2 had minimal and small NPAs, respectively. Eyes in clusters 3 and 4 exhibited NPAs in the temporal and inferotemporal regions, respectively. Eyes in cluster 5 displayed NPAs in both superonasal and inferonasal areas. The unique NPA distributions in each cluster encouraged us to propose eight possible pathways of NPA progression. DR severity was not equal between clusters (P < 0.001), for example, 8 (15.7%) of 51 eyes and 15 (65.2%) of 23 eyes had PDR in clusters 1 and 5, respectively. Dimensionality reduction and subsequent clustering based on the NPA distribution on widefield OCTA enabled the inference of possible NPA progression in DR.

Is There a Nonperfusion Threshold on OCT Angiography Associated With New Vessels Detected on Ultra-Wide-Field Imaging in Diabetic Retinopathy?

To determine whether the nonperfusion index (NPI) measured on widefield (WF) optical coherence tomography angiography (OCTA) could be used as an alternative method for the diagnosis of proliferative diabetic retinopathy (PDR) and to study the relationship between the NPI and the location of new vessels (NV) in eyes with PDR. Fifty-one treatment-naïve eyes with either severe nonproliferative DR (NPDR) or PDR were imaged using ultra-wide-field imaging and wide-field OCTA. The NPI was significantly higher in eyes with PDR (18.94% vs. 7.51%; P < 0.01). Using the NPI on the whole image to assess PDR status, the area under the curve was 0.770, but the area under the curve increased when the NPI of the most peripheral circle was used (area under the curve of 0.792). Four eyes with PDR (17%) had NV outside the OCTA image field, and their mean NPI (6.15 %) did not differ from that measured in severe NPDR eyes (7.51%; P = 0.67) and was lower than in other eyes with PDR (21.49%; P = 0.023). The presence of NV in a sector was associated with a higher NPI in the same sector (29.2% vs. 6.0%; P < 10-15). Although the NPI was significantly higher in eyes with PDR compared with severe NPDR eyes, its measurement on the whole wide-field OCTA image was not sensitive enough to replace the detection of NV for the diagnosis of PDR. Because the presence of new vessels was related to the local nonperfusion index in the same sector, the assessment of nonperfusion outside the optical coherence tomography angiography field is important in diabetic retinopathy.

Early Sign of Retinal Neovascularization Evolution in Diabetic Retinopathy: A Longitudinal OCT Angiography Study

To assess whether the combination of en face OCT and OCT angiography (OCTA) can capture observable, but subtle, structural changes that precede clinically evident retinal neovascularization (RNV) in eyes with diabetic retinopathy (DR). Retrospective, longitudinal study. Patients with DR that had at least 2 visits. We obtained wide-field OCTA scans of 1 eye from each participant and generated en face OCT, en face OCTA, and cross-sectional OCTA. We identified eyes with RNV sprouts, defined as epiretinal hyperreflective materials on en face OCT with flow signals breaching the internal limiting membrane on the cross-sectional OCTA without recognizable RNV on en face OCTA and RNV fronds, defined as recognizable abnormal vascular structures on the en face OCTA. We examined the corresponding location from follow-up or previous visits for the presence or progression of the RNV. The characteristics and longitudinal observation of early signs of RNV. From 71 eyes, we identified RNV in 20 eyes with the combination of OCT and OCTA, of which 13 (65%) were photographically graded as proliferative DR, 6 (30%) severe nonproliferative DR, and 1 (5%) moderate nonproliferative diabetic retinopathy. From these eyes, we identified 38 RNV sprouts and 26 RNV fronds at the baseline. Thirty-four RNVs (53%) originated from veins, 24 (38%) were from intraretinal microabnormalities, and 6 (9%) were from a nondilated capillary bed. At the final visit, 53 RNV sprouts and 30 RNV fronds were detected. Ten eyes (50%) showed progression, defined as having a new RNV lesion or the development of an RNV frond from an RNV sprout. Four (11%) RNV sprouts developed into RNV fronds with a mean interval of 7.0 months. Nineteen new RNV sprouts developed during the follow-up, whereas no new RNV frond was observed outside an identified RNV sprout. The eyes with progression were of younger age (P= 0.014) and tended to be treatment naive (P= 0.07) compared with eyes without progression. Longitudinal observation demonstrated that a combination of en face OCT and cross-sectional OCTA can identify an earlier form of RNV before it can be recognized on en face OCTA. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Automatic diagnosis of diabetic retinopathy using vision transformer based on wide-field optical coherence tomography angiography

Diabetic retinopathy (DR) is one of the major causes of visual impairment in adults with diabetes. Optical coherence tomography angiography (OCTA) is nowadays widely used as the golden criterion for diagnosing DR. Recently, wide-field OCTA (WF-OCTA) provided more abundant information including that of the peripheral retinal degenerative changes and it can contribute in accurately diagnosing DR. The need for an automatic DR diagnostic system based on WF-OCTA pictures attracts more and more attention due to the large diabetic population and the prevalence of retinopathy cases. In this study, automatic diagnosis of DR using vision transformer was performed using WF-OCTA images (12[Formula: see text]mm × 12[Formula: see text]mm single-scan) centered on the fovea as the dataset. WF-OCTA images were automatically classified into four classes: No DR, mild nonproliferative diabetic retinopathy (NPDR), moderate to severe NPDR, and proliferative diabetic retinopathy (PDR). The proposed method for detecting DR on the test set achieves accuracy of 99.55%, sensitivity of 99.49%, and specificity of 99.57%. The accuracy of the method for DR staging reaches up to 99.20%, which has been proven to be higher than that attained by classical convolutional neural network models. Results show that the automatic diagnosis of DR based on vision transformer and WF-OCTA pictures is more effective for detecting and staging DR.