Optical Coherence Tomography Angiography Features Research Articles

QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES FOR OBJECTIVE CLASSIFICATION AND STAGING OF DIABETIC RETINOPATHY.

This study aims to characterize quantitative optical coherence tomography angiography (OCTA) features of nonproliferative diabetic retinopathy (NPDR) and to validate them for computer-aided NPDR staging. One hundred and twenty OCTA images from 60 NPDR (mild, moderate, and severe stages) patients and 40 images from 20 control subjects were used for this study conducted in a tertiary, subspecialty, academic practice. Both eyes were photographed and all the OCTAs were 6 mm × 6 mm macular scans. Six quantitative features, that is, blood vessel tortuosity, blood vascular caliber, vessel perimeter index, blood vessel density, foveal avascular zone area, and foveal avascular zone contour irregularity (FAZ-CI) were derived from each OCTA image. A support vector machine classification model was trained and tested for computer-aided classification of NPDR stages. Sensitivity, specificity, and accuracy were used as performance metrics of computer-aided classification, and receiver operation characteristics curve was plotted to measure the sensitivity-specificity tradeoff of the classification algorithm. Among 6 individual OCTA features, blood vessel density shows the best classification accuracies, 93.89% and 90.89% for control versus disease and control versus mild NPDR, respectively. Combined feature classification achieved improved accuracies, 94.41% and 92.96%, respectively. Moreover, the temporal-perifoveal region was the most sensitive region for early detection of DR. For multiclass classification, support vector machine algorithm achieved 84% accuracy. Blood vessel density was observed as the most sensitive feature, and temporal-perifoveal region was the most sensitive region for early detection of DR. Quantitative OCTA analysis enabled computer-aided identification and staging of NPDR.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES OF SUBRETINAL FIBROSIS AFTER MYOPIC NEOVASCULARIZATION.

To describe the optical coherence tomography (OCT) angiography features of subretinal fibrosis in eyes with myopic choroidal neovascularization after natural evolution or secondary to intravitreal anti-vascular endothelial growth factor therapy. Retrospective observational case series. All eyes underwent a multimodal imaging examination including fluorescein angiography, spectral domain OCT, OCT angiography, and en face OCT. Twenty-five eyes of 25 patients with mean age of 56.4 ± 14.9 were included in the study. Subretinal fibrosis was diagnosed at mean 30 (range 6-116) months before inclusion. Within the subretinal fibrosis, an abnormal vascular network was observed in 20/25 (80%) eyes, located typically in the outer retina (18/20, 90%) or the choriocapillaris (14/20, 70%) segmentation. The most prevalent patterns were "round tangle" and "tapered tangle." On en face OCT, the subretinal fibrosis was evidenced in 24/25 (96%) eyes, most prevalently in the outer retina (21/25, 84%) and in the choriocapillaris (18/25, 72%), where main feature was white-hyperreflective (20/21, 95%) and dark-hyporeflective (17/18, 94%) appearance, respectively. The presence of subretinal fibrosis on en face OCT was positively correlated with the presence of abnormal vascular network on OCT angiography in 61% of the cases (P = 0.005). Subretinal fibrosis secondary to myopic choroidal neovascularization frequently contains blood flow within a persistent abnormal vascular network as assessed by OCT angiography.

Quantitative optical coherence tomography angiography: A review.

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.Impact statementOCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. Quantitative analysis of OCTA is essential to standardize objective interpretations of clinical outcome. This review summarizes technical rationales and clinical applications of quantitative OCTA features.

OCT Angiography Features of Neovascularization as Predictive Factors for Frequent Recurrence in Age-Related Macular Degeneration

To investigate the features of neovascularization (NV) in eyes with neovascular age-related macular degeneration using optical coherence tomography angiography (OCTA) according to the treatment interval of intravitreal aflibercept injection (IVI). Retrospective, interventional, comparative case series. Patients with type 1 NV treated with the "pro re nata" regimen after 3 loading IVI were classified into 2 groups based on the numbers of treatments during 12months, specifically a stable group who required fewer than 2 injections and an unstable group who required more than 3 injections. Quantitative features of OCTA including NV area, NV length, NV density, endpoint density (open-ended vessels per unit length), junction density (vessel junction per unit length), lacunarity, and largest vessel caliber were compared between the 2 groups. Among 71 eyes, 38 and 33 eyes were classified into the stable and unstable groups, respectively. The unstable group had higher endpoint densities (stable vs unstable: 2.72 vs 3.18; P= .03) and higher levels of lacunarity (0.177 vs 0.211; P= .028). The area, density, length of NV, junction density, and largest vessel caliber were not different between the 2 groups (P= .057, P= .184, P= .062, P= .160, and P= .473, respectively). Endpoint density was correlated with the unstable group in both univariate and multivariate analyses (P= .004, P= .002, respectively). A predictive model with an endpoint index demonstrated a sensitivity of 93.75% and a negative predictive value of 89.47% for the unstable group. The characteristics of NV in eyes of exudative age-related macular degeneration with type 1 NV were different according to treatment requirements. Identifying the features of NV on OCTA might be helpful for predicting clinical outcomes and optimal treatment intervals.

Quantitative Evaluation of the Retinal Vascular Parameters With OCTA in Patients With Behçet Disease Without Ocular Involvement.

To evaluate the optical coherence tomography angiography (OCTA) features of patients with Behçet disease (BD) without ocular involvement. Twenty-three patients with BD without ocular involvement and 29 healthy age/sex-matched control subjects were involved. The authors measured foveal avascular zone (FAZ) area, vessel density in the parafoveal region, and flow area (fovea-centered 3-mm radius area) in the superficial and deep capillary plexuses evaluated by OCTA. FAZ area was significantly larger in eyes with BD in both the superficial and deep capillary plexuses (0.331 vs. 0.240 mm2 [P = .004] and 0.352 vs. 0.257 mm2 [P = .003], respectively). Although mean capillary vessel density in parafoveal region and mean flow area were lower in eyes with BD for both superficial and deep capillary plexuses, these findings were not statistically significant. Microvascular changes in macular region can be identified in patients with BD without ocular manifestation. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:31-34.].

PHOTODYNAMIC THERAPY-INDUCED ACUTE EXUDATIVE MACULOPATHY: Incidence, Clinical Features, and Long-Term Outcomes.

To describe the incidence, clinical features, and long-term outcomes of photodynamic therapy (PDT)-induced acute exudative maculopathy (PAEM) in patients who underwent PDT for various indications. This retrospective observational case series included all cases who developed massive serofibrinous macular exudation within a week after PDT. Medical records of patients with post-PDT exudative events were reviewed for relevant data and imaging abstraction including optical coherence tomography and indocyanine green angiography features and were subjected to analysis. The incidence rate of PAEM was 4.52%, being noted in 8 eyes (out of 177 PDT sessions in 155 eyes) with a mean age of 70.25 ± 6.65 years. Pre-PDT factors commonly associated with PAEM included age ≥65 years (87.5%), clinical diagnosis of polypoidal choroidal vasculopathy (75%), spot size ≥3,500 µm (100%), best-corrected visual acuity of 20/40 or better (87.5%), low-fluence PDT (87.5%), and the first exposure to PDT (75%). Photodynamic therapy-induced acute exudative maculopathy was noted at a mean interval of 2.9 ± 1.7 days (2-7 days) after PDT. Photodynamic therapy-induced acute exudative maculopathy resulted in significant decrease in mean best-corrected visual acuity from logMAR 0.29 ± 0.21 (approximate Snellen equivalent 20/39) to logMAR 0.91 ± 0.37 (approximate Snellen equivalent 20/163) [P = 0.0018], and significant increase in mean central macular thickness from 228.1 ± 71.8 µm to 481.4 ± 154.8 µm (P = 0.0029). Photodynamic therapy-induced acute exudative maculopathy resolved to baseline or even better tomographic status at a mean interval of 4.6 ± 1.2 weeks, resulting in complete visual recovery compared with baseline. During mean follow-up of 77.8 ± 46.4 weeks after PDT, no activity was noted for a mean duration of 26.3 ± 42.5 weeks after resolution. At final visit, mean best-corrected visual acuity and central macular thickness was logMAR 0.49 ± 0.28 (approximate Snellen equivalent 20/62) and 153.6 ± 40.0 µm, respectively, with underlying pathology being stable in 50% of the eyes. Photodynamic therapy-induced acute exudative maculopathy is an uncommon complication with self-resolving course and favorable prognosis. Patients undergoing PDT should be warned of the possibility of PAEM. The factors frequently associated with PAEM include elderly age (>65 years), clinical diagnosis of polypoidal choroidal vasculopathy, larger spot size (≥3,500 µm), pre-PDT best-corrected visual acuity of 20/40 or better, low-fluence PDT, and the first exposure to PDT.

Features and Diagnostic Accuracy of Optical Coherence Tomography Angiography in Neovascular Age-related Macular Degeneration.

IntroductionAge-related macular degeneration (AMD) is one of the important causes of visual impairment in aging population. Fundus fluorescein angiography (FFA) is gold standard for the diagnosis of neovascular AMD (nAMD) while optical coherence tomography (OCT) aids in the diagnosis of nAMD and is very useful for follow-up. OCT angiography (OCTA) is an evolving imaging technology that can be used as a valid diagnostic tool to study morphology of choroidal neovascularization (CNV) that is seen in nAMD. This study was conducted with the objective to determine diagnostic accuracy and OCTA features of occult and classic CNV in patients with nAMD.MethodsIn this prospective observational study, 90 eyes of 58 patients with nAMD were studied with OCT, OCTA and FFA. OCTA scans were analyzed to qualitatively describe the morphological appearance of CNV in terms of location, pattern and configuration. The OCTA sensitivity and specificity for CNV detection were calculated by comparing it with FFA.ResultsFFA detected CNV in 70 of the 90 eyes (77.77%) whereas OCTA identified CNV in 69 eyes (76.7%). Among 69 eyes with CNV, it was well-defined in 51 (73.9%) eyes and poorly defined in 18 (26.1%) eyes. There were four false positive and five false negative cases. The sensitivity, specificity, positive predictive value and negative predictive value of OCTA in detection of nAMD were found to be 92.85%, 80.0%, 94.2 and 76.2, respectively.ConclusionOCTA is a useful, noninvasive, reproducible imaging tool for diagnosing, classifying and localizing CNV. The technique has high sensitivity and specificity and can be used reliably in cases where FFA is contraindicated or inconclusive.

Distinctive Mechanisms and Patterns of Exudative Versus Tractional Intraretinal Cystoid Spaces as Seen With Multimodal Imaging

To determine clear-cut distinctions between tractional and exudative intraretinal cystoid spaces subtypes. Retrospective, multicenter, observational case series. A cohort of patients diagnosed with intraretinal cystoid spaces and imaged with optical coherence tomography (OCT), fluorescein angiography (FA), blue fundus autofluorescence (BFAF), en face OCT, and OCT angiography (OCT-A) was included in the study. All images were qualitatively and quantitatively evaluated. In this study were included 72 eyes of 69 patients. Exudative intraretinal cystoid spaces (36/72 eyes, 50%) displayed a "petaloid" morphology as seen with en face OCT, FA, and BFAF. Tractional intraretinal cystoid spaces (24/72 eyes, 33.3%), displayed a radial "spoke-wheel" en face OCT pattern. There was no leakage with FA and BFAF did not reveal specific patterns. Eyes with full-thickness macular hole (FTMH, 12/72 eyes, 16.7%) displayed a "sunflower" en face OCT appearance. FTMH showed OCT, OCT-A, and BFAF features of both exudative and tractional cystoid spaces, but without any FA leakage. Inner nuclear layer (INL) thickness was significantly lower in tractional cystoid spaces (P < .001). There were a greater number of INL cystoid spaces in both the exudative and FTMH subgroups (P= .001). The surface area of INL cystoid spaces was significantly lower in the tractional subgroup (P < .001). There was a significant reduction of the microvascular density in eyes with exudative vs tractional (P= .002) and FTMH (P < .001) subgroups. Exudative and tractional intraretinal cystoid spaces displayed characteristic multimodal imaging features and they may represent 2 different pathologic conditions with equally different clinical implications.

Assessment of Exudative Activity of Choroidal Neovascularization in Age-Related Macular Degeneration by OCT Angiography

Purpose: Based on exudative activity, choroidal neovascularization (CNV) in age-related macular degeneration (AMD) can be classified as “active” aCNV, pretherapied “silent” sCNV (i.e., a treatment-free interval >12 weeks), or treatment-naïve “quiescent” qCNV. We evaluated the qualitative and quantitative optical coherence tomography angiography (OCTA) features of these CNV subgroups. Methods: The presence of small-caliber vessels, peripheral arcades, and a ­perilesional OCTA signal attenuation as well as values for vessel length, density, and branching index were evaluated for each CNV network in a 6 × 6 mm OCTA scan pattern. Results: Fifty-one eyes of 51 patients with AMD (age 75.9 ± 7.5 years; 20 males [39.2%]) were included. The qCNV subgroup (n = 8) showed the highest prevalence of qualitative and quantitative values for OCTA activity criteria, reaching significance with regard to small-caliber vessels (p = 0.003), peripheral arcades (p = 0.039), vessel length (p = 0.020), and branching index (p < 0.001) when compared to the aCNV (n = 32) and sCNV (n = 11) subgroups. Qualitative criteria were inversely associated with the number of previous anti-VEGF injections (each p < 0.03), while quantitative metrics also suggested lower values. Conclusions: These findings suggest that OCTA may be supportive in the phenotypical differentiation of CNV lesions secondary to AMD, while the assessed structural changes appeared to be more indicative of previously administered anti-VEGF therapy than current exudative activity.

OCT angiography features associated with macular edema recurrence after intravitreal bevacizumab treatment in branch retinal vein occlusion

We aimed to evaluate the relationship between the capillary abnormalities including nonperfusion area (NPA) in optical coherence tomography angiography (OCTA) images and the recurrence of macular edema (ME) secondary to branch retinal vein occlusion (BRVO) after intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF; bevacizumab). The records of 40 patients who underwent intravitreal bevacizumab injection for ME secondary to BRVO and had at least six months of follow-up were reviewed. Central retinal thickness (CRT; μm) and macular edema type were evaluated prior to treatment. After ME resolution, nonperfusion areas in the 1 mm (NPA1) and 1–3 mm (NPA3) zones on the Early Treatment Diabetic Retinopathy Study (ETDRS) circle within the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were measured using OCTA images. Furthermore, other microvascular abnormalities in the both SCP and DCP were compared between groups. ME recurred in 25 of 40 (62.5%) eyes. The NPA1 of the SCP and DCP (p = 0.002, 0.004, respectively), NPA3 of the SCP and DCP (p = 0.002, 0.008, respectively), and initial CRT (p = 0.022) differed significantly between eyes with and without ME recurrence. In multivariate logistic regression analyses, the NPA1 of the DCP (OR: 344.718; p = 0.029) and NPA3 of the SCP (OR: 4.072; p = 0.018) were significantly associated with ME recurrence. Other microvascular abnormalities were not significantly different between two groups. The central NPA and parafoveal NPA of the SCP in OCTA images correlated strongly with ME recurrence in BRVO patients after intravitreal anti-VEGF injection.

DETECTION OF TYPE 1 CHOROIDAL NEOVASCULAR MEMBRANES USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN TUBERCULAR POSTERIOR UVEITIS.

To study optical coherence tomography angiography (OCTA) and multimodal imaging features of Type 1 inflammatory choroidal neovascularization (CNV) in tubercular serpiginous-like choroiditis and response to anti-vascular endothelial growth factor therapy. In this study, multimodal imaging was performed using OCTA, enhanced-depth imaging optical coherence tomography, fluorescein angiography, and indocyanine green angiography. Correlation of OCTA with other imaging modalities in the detection of CNV was performed. The changes in CNV configuration after anti-vascular endothelial growth factor therapy were assessed. In this study, nine eyes (8 patients; 5 females; mean age: 32.5 ± 11.57 years) with diagnosis of tubercular serpiginous-like choroiditis were included. All the eyes had presence of low-lying pigment epithelial detachments on enhanced-depth imaging optical coherence tomography. Using OCTA, it was possible to detect Type 1 CNV in all eyes. Type 1 CNV networks comprised fine anastomotic network of vessels, some of which had a hairpin loop configuration. After anti-vascular endothelial growth factor therapy, there was a decrease in branching and anastomosis. The visual acuity significantly improved from 0.49 ± 0.26 (20/60 Snellen equivalent) at baseline to 0.26 ± 0.17 (20/36 Snellen equivalent) (P = 0.03) in all eyes. Type 1 CNV can occur among patients with tubercular serpiginous-like choroiditis, leading to significant visual loss even in the healed stages of the disease. Optical coherence tomography angiography can help in the detection of Type 1 CNV where conventional multimodal imaging, including fluorescein angiography and OCT, fails to make a definitive diagnosis and thereby guide the initiation of anti-vascular endothelial growth factor therapy.

Optical coherence tomography angiography characteristics of acute retinal arterial occlusion

BackgroundTo characterize the vascular changes in eyes within the acute phase of retinal arterial occlusion (RAO) by optical coherence tomography angiography (OCT-A) imaging.MethodsThis was a retrospective, observational study. Nineteen patients with RAO (symptom onset within 7 days) and 19 age and sex-matched normal control individuals were included. A comprehensive ophthalmic examination and OCT-A examination were conducted for all the patients.ResultsThe vessel density of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and area with a width of 300 μm around the FAZ (FD-300) was significantly reduced in RAO patients compared with that in the fellow eyes and normal control eyes. The vessel density of the SCP of RAO fellow eyes was significantly lower than that of the normal control eyes (all P < 0.05). Though no difference was observed in the FAZ of RAO eyes compared with that of fellow eyes and normal control eyes, the acircularity index (AI) of the FAZ was significantly increased in RAO eyes (P < 0.05). Central macular thickness (CMT) was correlated with best-corrected visual acuity in central retinal arterial occlusion (CRAO) patients (r = 0.626, P = 0.024). In BRAO eyes, the vessel density of the RAO-affected hemifield was significantly reduced compared with that of the unaffected hemifield (P < 0.05). Radial peripapillary plexus (RPC) vessel density was reduced, accompanied by retinal nerve fiber layer (RNFL) thinning in 3 available CRAO patients.ConclusionsAs a valuable noninvasive imaging tool, OCT-A provides deeper and more detailed vascular information that extends our understanding of the vasculature alterations in acute RAO.

Optical coherence tomography angiography characteristics of choroidal neovascularization requiring varied dosing frequencies in treat-and-extend management: An analysis of the AVATAR study.

PurposeTo evaluate optical coherence tomography angiography (OCTA) characteristics of choroidal neovascularization (CNV) in eyes requiring different treatment frequency of anti-vascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (NVAMD).DesignProspective observational case series.MethodsSubjects who had undergone anti-VEGF treatment for NVAMD in the AVATAR study were subdivided into 3 groups depending on required anti-VEGF dosing: (i) treat-and-extend requiring every 4–6 weeks dosing (TEq4-6w), (ii) treat-and-extend requiring every 7–12 weeks dosing (TEq7-12w), (iii) eyes not requiring injection within last 12 months (PRN >12mo). OCTA images were evaluated for the morphological characteristics of CNV and the choriocapillaris flow void.ResultsStudy consisted 40 eyes of 31 patients with a mean age of 79.9 ± 6.2 years. CNV morphology analysis on OCTA was feasible in 29 (73%) eyes. Ninety percent of CNVs in TEq7-12w group were irregular in shape involving foveal center, while 67% of CNVs in PRN>12mo group were circular in shape sparing foveal center. Among three groups, statistical difference was found in CNV shape (P = .012) and CNV location (P = .003), while no statistical difference was found in the CNV area (P = .14), vessel density (P = .19), presence of core vessels (P = .23), the presence of small margin loops (P = .20), large margin loops (P = .14), CNV maturity (P = .40), or the mean percentage of choriocapillaris area with flow void (P = .66).ConclusionThe combination of CNV sparing the foveal center with higher circularity may suggest a clinically inactive CNV following initial anti-VEGF therapy. We found minimal distinguishing OCTA characteristics between those eyes that required ongoing therapy with the treat-and-extend regimen. More research is needed to identify specific CNV characteristics on OCTA that may become a useful tool for the management of NVAMD and timing of treatment.

Supervised Machine Learning Based Multi-Task Artificial Intelligence Classification of Retinopathies

Artificial intelligence (AI) classification holds promise as a novel and affordable screening tool for clinical management of ocular diseases. Rural and underserved areas, which suffer from lack of access to experienced ophthalmologists may particularly benefit from this technology. Quantitative optical coherence tomography angiography (OCTA) imaging provides excellent capability to identify subtle vascular distortions, which are useful for classifying retinovascular diseases. However, application of AI for differentiation and classification of multiple eye diseases is not yet established. In this study, we demonstrate supervised machine learning based multi-task OCTA classification. We sought (1) to differentiate normal from diseased ocular conditions, (2) to differentiate different ocular disease conditions from each other, and (3) to stage the severity of each ocular condition. Quantitative OCTA features, including blood vessel tortuosity (BVT), blood vascular caliber (BVC), vessel perimeter index (VPI), blood vessel density (BVD), foveal avascular zone (FAZ) area (FAZ-A), and FAZ contour irregularity (FAZ-CI) were fully automatically extracted from the OCTA images. A stepwise backward elimination approach was employed to identify sensitive OCTA features and optimal-feature-combinations for the multi-task classification. For proof-of-concept demonstration, diabetic retinopathy (DR) and sickle cell retinopathy (SCR) were used to validate the supervised machine leaning classifier. The presented AI classification methodology is applicable and can be readily extended to other ocular diseases, holding promise to enable a mass-screening platform for clinical deployment and telemedicine.

Imaging analysis with optical coherence tomography angiography after primary repair of macula-off rhegmatogenous retinal detachment.

To evaluate changes in the microcirculation of various retinal layers and choroid following successful repair of macula-off rhegmatogenous retinal detachment (RRD) using optical coherence tomography angiography (OCTA). Twenty-eight patients (28 eyes) who underwent successful repair of macula-off RRD were prospectively investigated. Differences in OCTA characteristics between retinal detachment (RD) and fellow eyes were compared. Quantitative measurements of the retinal capillary and choriocapillary associated with the preoperative and intraoperative factors were analyzed. The mean vessel and parafoveal vessel densities were significantly lower in the superficial retinal capillary plexus (SCP) and deep retinal capillary plexus (DCP) in the RD eyes than the fellow eyes. Presence of preoperative intraretinal separation in the RD eyes was significantly associated with both an enlarged foveal avascular zone (P =0.022) and a lower DCP vessel density (P= 0.031) postoperatively. Eyes with a scleral buckle alone had a greater postoperative subfoveal choroidal thickness (P =0.037). Eyes undergoing vitrectomy alone had a higher postoperative vessel density in the choriocapillaris (P= 0.035). Eyes undergoing a vitrectomy and scleral buckle had a lower SCP (P =0.031) and DCP (P =0.035) vessel density postoperatively. Macula-off RRD may cause not only retinal structural damage but also decreased retinal perfusion even after successful anatomical repair. Our findings suggested that RD eyes had a significantly lower vessel density than fellow eyes after surgery. The combined procedure might result in a lower vessel density, as compared with a scleral buckle or vitrectomy alone.

OPTICAL COHERENCE TOMOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY EVALUATION OF COMBINED HAMARTOMA OF THE RETINA AND RETINAL PIGMENT EPITHELIUM.

To study multimodal imaging features of combined hamartoma of the retina and retinal pigment epithelium (CHRRPE). Six patients (3 males, mean age 11 years) and a healthy age-matched control group made up of 15 healthy subjects (8 males, mean age 12.6 years) were included in the analysis. Complete ophthalmologic examination was performed, including best-corrected visual acuity, anterior and posterior segment slit-lamp evaluation, and tonometry. The multimodal imaging protocol included fundus images, structural optical coherence tomography (OCT), and swept-source OCT angiography (OCTA). The main outcome measures included the qualitative evaluation of both OCT and OCTA features of CHRRPE, retinal and choroidal thickness measurements, and the quantitative analysis of superficial capillary plexus, deep capillary plexus, and choriocapillaris vessel densities. Optical coherence tomography features of CHRRPE were examined extensively. Multiple little hyperreflective triangular outer retinal alterations were found at the CHRRPE edges in all patients; these were dubbed the "shark-teeth" sign. Optical coherence tomography angiography showed rarefaction and morphologic alterations of all retinal plexa. Moreover, quantitative analysis revealed a statistically significant decrease in superficial capillary plexus, deep capillary plexus, and choriocapillaris vessel densities in patients affected by CHRRPE compared with the control group. Optical coherence tomography and OCTA analyses allowed the accurate qualitative and quantitative analyses of CHRRPE features. Further studies are needed to better define OCTA changes of CHRRPE better and to improve our understanding of the possible causes of the shark-teeth sign.

Optical coherence tomography angiography in optic nerve sheath meningioma

Abstract This study describes Spectral Domain-Optical Coherence Tomography (SD-OCT) and Optical Coherence Tomography Angiography (OCTA) features of Optic Nerve Sheath Meningioma (ONSM). A 22-year-old woman, diagnosed with meningioma encircling the right optic nerve inside the intraorbital segment optic canal at the magnetic resonance imaging, showed a normal fundus examination. Instead, SD-OCT and OCTA revealed alterations in the neurostructure and microvascular network of the optic nerve. Despite fundoscopy and fluorescein angiography, SD-OCT and OCTA represent valid, non-invasive and reliable methods to evaluate neurostructural and vascular irregularities in this benign tumor of the optic nerve.

Assessment of chronic radiation proctopathy and radiofrequency ablation treatment follow-up with optical coherence tomography angiography: A pilot study.

BACKGROUNDChronic radiation proctopathy (CRP) occurs as a result of pelvic radiation therapy and is associated with formation of abnormal vasculature that may lead to persistent rectal bleeding. While incidence is declining due to refinement of radiation delivery techniques, CRP remains one of the major complications of pelvic radiation therapy and significantly affects patient quality of life. Radiofrequency ablation (RFA) is an emerging treatment modality for eradicating abnormal vasculature associated with CRP. However, questions remain regarding CRP pathophysiology and optimal disease management.AIMTo study feasibility of optical coherence tomography angiography (OCTA) for investigating subsurface vascular alterations in CRP and response to RFA treatment.METHODSTwo patients with normal rectum and 8 patients referred for, or undergoing endoscopic RFA treatment for CRP were imaged with a prototype ultrahigh-speed optical coherence tomography (OCT) system over 15 OCT/colonoscopy visits (2 normal patients, 5 RFA-naïve patients, 8 RFA-follow-up visits). OCT and OCTA was performed by placing the OCT catheter onto the dentate line and rectum without endoscopic guidance. OCTA enabled depth-resolved microvasculature imaging using motion contrast from flowing blood, without requiring injected dyes. OCTA features of normal and abnormal microvasculature were assessed in the mucosa and submucosa. Blinded reading of OCTA images was performed to assess the association of abnormal rectal microvasculature with CRP and RFA treatment, and rectal telangiectasia density endoscopic scoring.RESULTSOCTA/OCT images are intrinsically co-registered and enabled depth-resolved visualization of microvasculature in the mucosa and submucosa. OCTA visualized normal vascular patterns with regular honeycomb patterns vs abnormal vasculature with distorted honeycomb patterns and ectatic/tortuous microvasculature in the rectal mucosa. Normal arterioles and venules < 200 μm in diameter versus abnormal heterogenous enlarged arterioles and venules > 200 μm in diameter were visualized in the rectal submucosa. Abnormal mucosal vasculature occurred in 0 of 2 normal patients and 3 of 5 RFA-naïve patients, while abnormal submucosal vasculature occurred more often, in 1 of 2 normal patients and 5 of 5 RFA-naïve patients. After RFA treatment, vascular abnormalities decreased, with abnormal mucosal vasculature observed in 0 of 8 RFA-follow-up visits and abnormal submucosal vasculature observed in only and 2 of 8 RFA-follow-up visits.CONCLUSIONOCTA visualizes depth-resolved microvascular abnormalities in CRP, allowing assessment of superficial features which are endoscopically visible as well as deeper vasculature which cannot be seen endoscopically. OCTA/OCT of the rectum can be performed in conjunction with, or independently from endoscopy. Further studies are warranted to investigate if OCTA/OCT can elucidate pathophysiology of CRP or improve management.

Fully automated geometric feature analysis in optical coherence tomography angiography for objective classification of diabetic retinopathy.

This study is to establish quantitative features of vascular geometry in optical coherence tomography angiography (OCTA) and validate them for the objective classification of diabetic retinopathy (DR). Six geometric features, including total vessel branching angle (VBA: θ), child branching angles (CBAs: α1 and α2), vessel branching coefficient (VBC), and children-to-parent vessel width ratios (VWR1 and VWR2), were automatically derived from each vessel branch in OCTA. Comparative analysis of heathy control, diabetes with no DR (NoDR), and non-proliferative DR (NPDR) was conducted. Our study reveals four quantitative OCTA features to produce robust DR detection and staging classification: (ANOVA, P<0.05), VBA, CBA1, VBC, and VWR1.

Inner Retinal Layer and Outer Retinal Layer Findings after Macular Hole Surgery Assessed by means of Optical Coherence Tomography.

Aim To summarize the spectrum of optical coherence tomography (OCT) and OCT angiography (OCTA) features after full-thickness macular hole (MH) repair surgery. Methods A PubMed engine search was carried out using the terms “Macular Hole,” “Optical Coherence Tomography,” and “Optical Coherence Tomography Angiography.” All reports published in English up to October 2018, irrespective of their publication status, were included. Tomographic signs analyzed were divided according to the involved portion of the retina in “inner retinal layers” and “external retinal layers.” Despite predominantly involving the inner retinal layers, cystoid macular edema (CME) has been treated as a separate entity. Finally, report on vessel density (VD) changes and the foveal avascular zone (FAZ) area modifications have been included. Results Different clinical findings can be observed on OCT of patients who underwent MH repair surgery. There is general consent that retinal thinning involving primarily the retinal nerve fiber layer and the ganglion cell layer takes place after surgery. In the postoperative period, the outermost retinal layers get progressively restored. Persistent defects in the ellipsoid zone or in the external limiting membrane correlate with worse postoperative visual outcome. OCTA has globally demonstrated that eyes after MH closure show a reduction in macular and paramacular VD and smaller FAZ areas, compared with control or fellow eyes. Conclusion Clinicians should be aware of the most common tomographic findings to properly manage each condition. In addition, significant advantages for the postoperative application of OCT and OCTA include noninvasiveness, rapid and simple execution, repeatability, and precise measurements.