Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

Clinical Applications of Optical Coherence Tomography Angiography in Inherited Retinal Diseases: An Up-to-Date Review of the Literature

Optical coherence tomography angiography (OCT-A) is a valuable imaging technique, allowing non-invasive, depth-resolved, motion-contrast, high-resolution images of both retinal and choroidal vascular networks. The imaging capabilities of OCT-A have enhanced our understanding of the retinal and choroidal alterations that occur in inherited retinal diseases (IRDs), a group of clinically and genetically heterogeneous disorders that may be complicated by several vascular conditions requiring a prompt diagnosis. In this review, we aimed to comprehensively summarize all clinical applications of OCT-A in the diagnosis and management of IRDs, highlighting significant vascular findings on retinitis pigmentosa, Stargardt disease, choroideremia, Best disease and other less common forms of retinal dystrophies. All advantages and limitations of this novel imaging modality will be also discussed.

Study on the Effects of Different anti-VEGF drugs on Fibrovascular Membranes of Proliferative Diabetic Retinopathy

PURPOSE

To investigate the effects of different anti-VEGF drugs on fibrovascular membranes (FVM) in proliferative diabetic retinopathy (PDR). In addition, in vitro model was used to simulate the intraocular fibroblasts barrier to explore the penetration of different anti-VEGF drugs.

METHODS

24 eyes from 24 PDR patients with FVM were recruited for this prospective observational study. The patients were randomized to receive one of three anti-VEGF drugs (Ranibizumab, Conbercept, or Aflibercept). Then neovascular structures were assessed by optical coherence tomography angiography (OCTA) before intravitreal injection (pre-IVT) and 1, 2, and 3 days after intravitreal injection (post-IVT). The changes in vessels area (VSA), vessels percentage area (VPA), junction density (JD), and average lacunarity (AL) were analyzed by using the image processing software Angiotool. In vitro penetrating model with fibroblasts barrier was used to compare the effects of the three drugs on human retinal vascular endothelial cells (HRVECs) over 3 days by Cell proliferation measurement. Moreover, the drug concentrations in the penetrating model were detected by liquid chromatography-mass spectrometry (LC-MS).

RESULTS

The VSA, VPA, and JD all decreased, while the AL increased in Ranibizumab group(n=8), Conbercept group (n=8), and Aflibercept group (n=8) within 3 days (P<0.05). Meanwhile, under the condition of the same amount of substance, the inhibition effect of Ranibizumab on HRVEC was the strongest in the penetrating model evaluated by CCK8 absorbance experiments of HRVECs (F_CCK8=6.493, P_CCK8= 0.0051), and the number of transmembrane molecules in the Ranibizumab group was also the largest within 3 days (F=8.209, P=0.0006) among the three groups.

CONCLUSION

Angiotool is feasible to reconstruct the neovascular structure on the FVM in OCTA images. The three different anti-VEGF drugs can significantly reduce the vascular area and density on the proliferating membranes, and there is no significant difference in the anti-neovascularization among the three drugs clinically. However, small molecule drug is more penetrating and move faster across membranes in vitro cell model.

CLINICAL TRIAL REGISTRATION

This trial is registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn, registration number ChiCTR2300067476).

Evaluation of retinal microvasculature in exotropia with abnormal binocular vision by optical coherence tomography angiography

BACKGROUND

To explore the retinal microvasculature in large-angle concomitant exotropia patients with abnormal binocular vision using optical coherence tomography angiography (OCTA) analysis.

METHODS

OCTA images of 52 healthy and 100 strabismic eyes were analyzed to quantify the retinal thickness (RT), superficial capillary plexus (SCP), deep capillary plexus (DCP), and foveal avascular zone (FAZ). Paired t-tests were performed to compare differences between the two groups, the dominant eye and the deviated eye in the exotropia group, respectively. A p-value < 0.01 was considered significant.

RESULTS

The mean angle of deviation was 79.38 [± 25.64] (prism diopters, PD). There were significant differences in the DCP in deviated eyes between the exotropia group and the control group (fovea: p = 0.007; temporal: p = 0.014; nasal: p = 0.028; inferior: p = 0.013). The temporal SCP in the exotropia group was significantly higher than in the control group in deviated eyes (p = 0.020). No significant difference was found between dominant eyes and strabismic eyes (p > 0.01).

CONCLUSIONS

The study showed that OCTA revealed subnormal DCP in patients with large-angle exotropia and abnormal binocularity which may be related to retinal suppression. Changes in the macular microvasculature may provide valuable insights into the development of strabismus. Further studies are needed to determine the clinical relevance of this finding.

TRIAL REGISTRATION

This trial is registered as ChiCTR2100052577 at www.Chictr.org.cn .

Relationship between choroidal thickness and vascular density in young healthy population

BACKGROUND AND PURPOSE

The purpose is to analyze choroidal vascular density (VD) in healthy individuals and to compare it with choroidal thickness (CT).

MATERIALS AND METHODS

Cross-sectional study enrolling healthy individuals between 18 and 35 years old of Caucasian race and with an axial length (AL) 21-26 mm. Choroid was imaged with swept-source optical coherence tomography angiography (OCTA) Triton DRI (Topcon) and a macular cube of 6 x 6 mm was obtained. CT values were automatically given by the software. VD values were obtained through codifying colors of the VD map into numbers.

RESULTS

102 (51 patients) were analyzed. Mean age was 27.32 ± 3.94 years old, mean intraocular pressure was 18.07 ± 2.38 mmHg, and mean AL was 23.71 ± 0.66 mm. CT was higher in the vertical axis and lower when approaching nasal and temporal sides. The highest CT was in superior macula. The highest choroidal VD were in the fovea and in the juxtapapillary region. The lowest choroidal VD were found in superior and inferior macular areas. Moderate inverse correlations between CT and choroidal VD were found in the juxtapapillary and inferior regions.

CONCLUSIONS

The choroid has a thickness pattern that differs from retina. Choroidal vessels represent a very high percentage of choroid in the peripapillary region and in the fovea. On the contrary, superior and inferior macula reveals low values of VD.

Functional OCT angiography reveals early retinal neurovascular dysfunction in diabetes with capillary resolution

Altered retinal neurovascular coupling may contribute to the development and progression of diabetic retinopathy (DR) but remains highly challenging to measure due to limited resolution and field of view of the existing functional hyperemia imaging. Here, we present a novel modality of functional OCT angiography (fOCTA) that allows a 3D imaging of retinal functional hyperemia across the entire vascular tree with single-capillary resolution. In fOCTA, functional hyperemia was evoked by a flicker light stimulation, recorded by a synchronized time-lapse OCTA (i.e., 4D), and extracted precisely from each capillary segment (space) and stimulation period (time) in the OCTA time series. The high-resolution fOCTA revealed that the retinal capillaries, particularly the intermediate capillary plexus, exhibited apparent hyperemic response in normal mice, and significant functional hyperemia loss (P < 0.001) at an early stage of DR with few overt signs of retinopathy and visible restoration after aminoguanidine treatment (P < 0.05). Retinal capillary functional hyperemia has strong potential to provide sensitive biomarkers of early DR, and retinal fOCTA would provide new insights into the pathophysiology, screening and treatment of early DR.

Degree of loss in the tissue thickness, microvascular density, specific perimetry and standard perimetry in early glaucoma

Objective

To identify the degree of loss of the circumpapillary retinal nerve fibre layer (cpRNFL), the layer from the macular RNFL to the inner plexiform layer (mGCL++), circumpapillary (cpVD) and macular vascular density (mVD), Pulsar perimetry and standard perimetry in early glaucoma.

Methods

In this cross-sectional study, one eye from each of 96 healthy controls and 90 eyes with open-angle glaucoma were measured with cpRNFL, mGCL++, cpVD, mVD, Pulsar perimetry with Octopus P32 test (Pulsar) and standard perimetry with Humphrey field analyser 24-2 test (HFA). For direct comparison, all parameters were converted to relative change values adjusted in both their dynamic range and age-corrected normal value.

Results

The degree of loss in mGCL++ (−24.7%) and cpRNFL (−25.8%) was greater than that in mVD (−17.3%), cpVD (−14.9%), Pulsar (−10.1%) and HFA (−5.9%) (each p<0.01); the degree of loss in mVD and cpVD was greater than that in Pulsar and HFA (each p<0.01); and the degree of loss in Pulsar was greater than that in HFA (p<0.01). The discrimination ability between glaucomatous and healthy eyes (area under the curve) was higher for mGCL++ (0.90) and cpRNFL (0.93) than for mVD (0.78), cpVD (0.78), Pulsar (0.78) and HFA (0.79).

Conclusion

The degree of loss of cpRNFL and mGCL++ thickness preceded by approximately 7%–10% and 15%–20% compared with the micro-VD and visual fields in early glaucoma, respectively.

Trial registration number

UMIN Clinical Trials Registry (http://www.umin.ac.jp/; R000046076 UMIN000040372).

Retinal microvascular changes in patients with coronary artery disease and apnea

BACKGROUND

Optical coherence tomography angiography (OCT-A) allowed visualization of capillary level of retina; however, the relationship between coronary vascular status and retinal microvascular changes in patients with apnea is not known well. Our aim was to assess the retinal OCT-A parameters in patients with ischemia and angiographically proven microvascular disease and compare them with obstructive coronary disease in patients with apnea.

METHODS

Our observational study included 185 eyes of 185 patients, 123 eyes of patients with apnea (72 eyes from mild OSAS, 51 eyes from moderate to severe OSAS) and 62 eyes from healthy controls. Radial scans of the macula and OCT-A scans of the central macula (superficial (SCP) and deep (DCP) capillary plexuses) were performed on all participants. All participants had documented sleep apnea disorder within 2 years prior to coronary angiography. Patients were grouped by severity of apnea and coronary atherosclerosis (50 % stenosis cut-off value for obstructive coronary artery disease). Patients presented with myocardial ischemia and without coronary artery occlusion (<50 % diameter reduction or FFR > 0.80) constitute the microvascular coronary artery (INOCA) group.

RESULTS

Compared to healthy controls, patients with apnea showed deterioration in vascular density in all regions of the retina, regardless of obstructive or microvascular coronary artery disease on the ischemia background. This study has provided important observations of a high prevalence of INOCA in patients with OSAS and the presence of OSAS was a significant independent predictor of functional coronary artery disease. The relative decreases in vascular densities were more pronounced in the DCP layer according to SCP layer of macula. Only FAZ area values were significantly different according to the severity of OSAS (0.27 (0.11-0.62) and 0.23 (0.07-0.50) (p = 0.012)).

CONCLUSIONS

In patients with apnea, OCT-A can be used as a noninvasive tool to define coronary artery involvement, with similar retinal microvascular changes both in obstructive and microvascular coronary artery group. In patients with OSAS, we observed a high prevalence of microvascular coronary disease, supporting pathophysiological role of OSAS in ischemia of this group of patients.

Fully automatic segmentation and monitoring of choriocapillaris flow voids in OCTA images

Optical coherence tomography angiography (OCTA) is a non-invasive ophthalmic imaging modality that is widely used in clinical practice. Recent technological advances in OCTA allow imaging of blood flow deeper than the retinal layers, at the level of the choriocapillaris (CC), where a granular image is obtained showing a pattern of bright areas, representing blood flow, and a pattern of small dark regions, called flow voids (FVs). Several clinical studies have reported a close correlation between abnormal FVs distribution and multiple diseases, so quantifying changes in FVs distribution in CC has become an area of interest for many clinicians. However, CC OCTA images present very complex features that make it difficult to correctly compare FVs during the monitoring of a patient. In this work, we propose fully automatic approaches for the segmentation and monitoring of FVs in CC OCTA images. First, a baseline approach, in which a fully automatic segmentation methodology based on local contrast enhancement and global thresholding is proposed to segment FVs and measure changes in their distribution in a straightforward manner. Second, a robust approach in which, prior to the use of our segmentation methodology, an unsupervised trained neural network is used to perform a deformable registration that aligns inconsistencies between images acquired at different time instants. The proposed approaches were tested with CC OCTA images collected during a clinical study on the response to photodynamic therapy in patients affected by chronic central serous chorioretinopathy (CSC), demonstrating their clinical utility. The results showed that both approaches are accurate and robust, surpassing the state of the art, therefore improving the efficacy of FVs as a biomarker to monitor the patient treatments. This gives great potential for the clinical use of our methods, with the possibility of extending their use to other pathologies or treatments associated with this type of imaging.

Rotational Distortion and Compensation in Optical Coherence Tomography with Anisotropic Pixel Resolution

Accurate image registration is essential for eye movement compensation in optical coherence tomography (OCT) and OCT angiography (OCTA). The spatial resolution of an OCT instrument is typically anisotropic, i.e., has different resolutions in the lateral and axial dimensions. When OCT images have anisotropic pixel resolution, residual distortion (RD) and false translation (FT) are always observed after image registration for rotational movement. In this study, RD and FT were quantitively analyzed over different degrees of rotational movement and various lateral and axial pixel resolution ratio (RL/RA) values. The RD and FT provide the evaluation criteria for image registration. The theoretical analysis confirmed that the RD and FT increase significantly with the rotation degree and RL/RA. An image resizing assisting registration (RAR) strategy was proposed for accurate image registration. The performance of direct registration (DR) and RAR for retinal OCT and OCTA images were quantitatively compared. Experimental results confirmed that unnormalized RL/RA causes RD and FT; RAR can effectively improve the performance of OCT and OCTA image registration and distortion compensation.

3-D OCT imaging of hyalocytes in partial posterior vitreous detachment and vaso-occlusive retinal disease

Purpose

To describe the spatial distribution and morphologic characteristics of macrophage-like cells called hyalocytes in the posterior vitreous cortex of a patient with unilateral partial posterior vitreous detachment (PVD) using coronal plane en face optical coherence tomography (OCT).

Observations

A 54-year-old male with sickle cell disease (HbSC genotype) presented with a partial PVD in one eye. Rendered volumes of a slab extending from 600 μm to 3 μm anterior to the inner limiting membrane (ILM) revealed hyperreflective foci in the detached posterior vitreous cortex suspended anterior to the macula, likely representing hyalocytes. In the fellow eye without PVD, hyperreflective foci were located 3 μm anterior to the ILM. The morphology of the cells in the eye with PVD varied between a ramified state with multiple elongated processes and a more activated state characterized by a plump cell body with fewer retracted processes. In the same anatomical location, the hyperreflective foci were 10-fold more numerous in the patient with vaso-occlusive disease than in an unaffected, age-matched control.

Conclusions and Importance

Direct, non-invasive, and label-free techniques of imaging cells at the vitreoretinal interface and within the vitreous body is an emerging field. The findings from this case report suggest that coronal plane en face OCT can be used to provide a detailed and quantitative characterization of cells at the human vitreo-retinal interface in vivo. Importantly, this case report demonstrates that 3D-OCT renderings can enhance visualization of these cells in relation to the ILM, which may provide clues concerning the identity and contribution of these cells to the pathogenesis of vitreo-retinal diseases.

Practical guidance for imaging biomarkers in exudative age-related macular degeneration

We provide an overview of current macular imaging techniques and identify and describe biomarkers that may be of use in the routine management of macular diseases, particularly exudative age-related macular degeneration (n-AMD). This perspective includes sections on macular imaging techniques including optical coherence tomography (OCT) and OCT angiography (OCTA), classification of exudative AMD, and biomarkers in structural OCT and OCTA. Fluorescein angiography remains a vital tool for assessing the activity of neovascular lesion, while indocyanine green angiography is the preferred option for choroidal vessels imaging in neovascular AMD. OCT provides a non-invasive three-dimensional visualization of retinal architecture in vivo and is useful in the diagnosis of many imaging biomarkers of AMD-related neovascular lesions including lesion activity. OCTA is a recent advance in OCT technology that allows accurate visualization of retinal and choroidal vascular flow. OCT and OCTA have led to an updated classification of exudative AMD lesions and provide several biomarkers that help to establish a diagnosis and the disease activity status of neovascular lesions. Individualization of therapy guided by OCT and OCTA biomarkers has the potential to further improve visual outcomes in exudative AMD. Moving forwards, integration of technologically advanced imaging equipment with AI software will help ophthalmologists to provide patients with the best possible care.

Characterization of the Structural and Functional Alteration in Eyes with Diabetic Macular Ischemia

OBJECTIVE

To investigate the relative effect of disorganization of the retinal inner layers (DRIL) and ellipsoid zone (EZ) loss on visual function in diabetic macular ischemia (DMI).

DESIGN

Prospective cross-sectional observational study.

PARTICIPANTS

Patients with stable treated proliferative diabetic retinopathy (PDR) without center-involved diabetic macular edema were recruited at the Moorfields Eye Hospital from December 2019 to November 2021. The main inclusion criteria were best-corrected visual acuity (BCVA) of ≥ 40 ETDRS letters (Snellen equivalent 20/160) with OCT angiography (OCTA) evidence of DMI in ≥ 1 eye.

METHODS

Each eligible eye of the recruited patients was assessed for BCVA, OCT, and OCTA metrics. The prespecified OCT parameters were DRIL and subfoveal EZ loss. Generalized estimating equations were used.

MAIN OUTCOMES MEASURES

The frequency of DRIL and EZ loss, their relative contributions to vision loss, and their associations with microvascular alterations were evaluated.

RESULTS

A total of 125 eyes of 86 patients with PDR were enrolled; 104 (83%) eyes had a BCVA of ≥ 70 letters. Disorganization of the retinal inner layers was more prevalent than EZ loss (46% [58 eyes] vs. 19% [24 eyes]). On average, the presence of DRIL had a more pronounced impact on vision, retinal thickness, and microvascular parameters than EZ loss. After multivariable adjustment, the odds of coexisting DRIL increased by 12% with every letter decrease in BCVA; however, there was no statistically significant association of subfoveal EZ loss with BCVA. In eyes with DRIL in the absence of EZ loss, the BCVA declined significantly by 6.67 letters compared with eyes with no DRIL nor EZ loss (95% confidence interval [CI], -9.92 to -3.41; P < 0.001). However, if DRIL and EZ loss coexisted, the resultant BCVA was 13.22 letters less than eyes without these structural abnormalities (95% CI, -18.85 to -7.59; P < 0.001).

CONCLUSIONS

In patients with DMI with a Snellen visual acuity of 20/160 or better, eyes with DRIL were associated with more visual function loss and retinal blood circulation alterations than those with subfoveal EZ loss only.

Ultrahigh resolution optical coherence tomography markers of normal aging and early age-related macular degeneration

Purpose

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.

Design

Prospective cross-sectional study.

Participants

A total of 53 nonexudative (dry) AMD eyes from 39 patients, and 63 normal eyes from 39 subjects.

Methods

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.

Main Outcome Measures

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).

Results

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.

Conclusions

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.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Combining Optical Coherence Tomography and Optical Coherence Tomography Angiography Longitudinal Data for the Detection of Visual Field Progression in Glaucoma

PURPOSE

To use longitudinal optical coherence tomography (OCT) and OCT angiography (OCTA) data to detect glaucomatous visual field (VF) progression with a supervised machine learning approach.

DESIGN

Prospective cohort study.

METHODS

One hundred ten eyes of patients with suspected glaucoma (33.6%) and patients with glaucoma (66.4%) with a minimum of 5 24-2 VF tests and 3 optic nerve head and macula images over an average follow-up duration of 4.1 years were included. VF progression was defined using a composite measure including either a "likely progression event" on Guided Progression Analysis, a statistically significant negative slope of VF mean deviation or VF index, or a positive pointwise linear regression event. Feature-based gradient boosting classifiers were developed using different subsets of baseline and longitudinal OCT and OCTA summary parameters. The area under the receiver operating characteristic curve (AUROC) was used to compare the classification performance of different models.

RESULTS

VF progression was detected in 28 eyes (25.5%). The model with combined baseline and longitudinal OCT and OCTA parameters at the global and hemifield levels had the best classification accuracy to detect VF progression (AUROC = 0.89). Models including combined OCT and OCTA parameters had higher classification accuracy compared with those with individual subsets of OCT or OCTA features alone. Including hemifield measurements significantly improved the models' classification accuracy compared with using global measurements alone. Including longitudinal rates of change of OCT and OCTA parameters (AUROCs = 0.80-0.89) considerably increased the classification accuracy of the models with baseline measurements alone (AUROCs = 0.60-0.63).

CONCLUSIONS

Longitudinal OCTA measurements complement OCT-derived structural metrics for the evaluation of functional VF loss in patients with glaucoma.

Optical coherence microscopy with a split-spectrum image reconstruction method for temporal-dynamics contrast-based imaging of intracellular motility

Biomedical researchers use optical coherence microscopy (OCM) for its high resolution in real-time label-free tomographic imaging. However, OCM lacks bioactivity-related functional contrast. We developed an OCM system that can measure changes in intracellular motility (indicating cellular process states) via pixel-wise calculations of intensity fluctuations from metabolic activity of intracellular components. To reduce image noise, the source spectrum is split into five using Gaussian windows with 50% of the full bandwidth. The technique verified that F-actin fiber inhibition by Y-27632 reduces intracellular motility. This finding could be used to search for other intracellular-motility-associated therapeutic strategies for cardiovascular diseases.

Central macular OCTA parameters in glaucoma

BACKGROUND/AIMS

To investigate the relationship between the foveal avascular zone (FAZ) parameters assessed by optical coherence tomography angiography (OCTA) and central visual field parameters in glaucoma and healthy subjects.

METHODS

One hundred and eighty-eight subjects (248 eyes), including 24 healthy (38 eyes), 37 glaucoma suspect (42 eyes, and 127 primary open angle glaucoma (POAG) patients (168 eyes), underwent imaging using OCTA and standard automated perimetry using the 24-2 and 10-2 Swedish Interactive Thresholding Algorithm. OCTA-based and OCT-based FAZ parameters (superficial FAZ area, FAZ circumference), foveal vessel density (FD300) and foveal thickness were measured. The correlation between FAZ parameters and visual field parameters was assessed using linear mixed model.

RESULTS

Axial length adjusted-FAZ area was not different among the three groups (mean (95% CI)): in healthy 0.31 (0.27 to 0.36) mm², glaucoma suspect 0.29 (0.26 to 0.31) mm² and POAG eyes 0.28 (0.27 to 0.30) mm² (p=0.578). FD300 was lower in glaucoma suspect 49.1% (47.9% to 50.4%) and POAG eyes 48.7% (48.1% to 49.4%) than healthy eyes 50.5% (49.3% to 51.7%) though the difference was not statistically significant (p=0.071). Lower FD300 was associated with worse 24-2 and 10-2 visual field mean deviation and foveal threshold in multivariable linear mixed models (all p<0.05). In addition, a smaller FAZ area was associated with lower intraocular pressure (IOP) (p=0.026).

CONCLUSIONS

The FD300, but not the FAZ area was correlated with 10° central visual field mean deviation and foveal threshold in healthy, glaucoma suspect and POAG eyes. In contrast, a smaller FAZ area was associated with lower IOP.

Peripapillary and macular vascular parameters by optical coherence tomography angiography in primary congenital glaucoma

OBJECTIVE

To evaluate the differences in peripapillary and macular vascular parameters by optical coherence tomography angiography (OCTA) between patients with primary congenital glaucoma (PCG) and healthy controls; and to determine their diagnostic accuracy.

MATERIAL AND METHODS

Observational, cross-sectional study including 39 eyes with PCG and 78 healthy eyes. Only one eye per patient was included. All included patients underwent a comprehensive ophthalmic examination and peripapillary and macular analysis were performed by AngioplexTM OCTA (Cirrus HD-OCT 5000) with a 4.5 × 4.5 mm optic nerve head scan and 6 × 6 mm macular scan. Global data and quadrant data from peripapillary vascular parameters and global data and circular sectors data from macular superficial plexus parameters were compared between groups. The glaucoma discrimination capability of these parameters was calculated as areas under the receiver operating characteristics curve (AUC ROC).

RESULTS

Mean age was 14.1 ± 8.7 years for the PCG patients and 11.7 ± 6.2 years for controls (p = 0.093). All vascular peripapillary measurements (global and quadrants; all p < 0.001) and all macular measurements (p < 0.042) excepting perfusion density in the inner circle (p = 0.087), were reduced in the PCG group compared to controls. According to AUC ROC, peripapillary (all ≥ 0.706) and macular parameters (all ≥ 0.699) showed good diagnostic capacity. AUC ROC for the most discriminatory measurements corresponding to blood flux index (0.887) and whole macula vascular density (0.855) were similar (p = 0.085).

CONCLUSION

Peripapillary and macular vascular parameters by OCTA are decreased in patients with PCG, showing a good capacity to discriminate between normal and glaucomatous eyes.

Reverse translation of artificial intelligence in glaucoma: Connecting basic science with clinical applications

Artificial intelligence (AI) has been approved for biomedical research in diverse areas from bedside clinical studies to benchtop basic scientific research. For ophthalmic research, in particular glaucoma, AI applications are rapidly growing for potential clinical translation given the vast data available and the introduction of federated learning. Conversely, AI for basic science remains limited despite its useful power in providing mechanistic insight. In this perspective, we discuss recent progress, opportunities, and challenges in the application of AI in glaucoma for scientific discoveries. Specifically, we focus on the research paradigm of reverse translation, in which clinical data are first used for patient-centered hypothesis generation followed by transitioning into basic science studies for hypothesis validation. We elaborate on several distinctive areas of research opportunities for reverse translation of AI in glaucoma including disease risk and progression prediction, pathology characterization, and sub-phenotype identification. We conclude with current challenges and future opportunities for AI research in basic science for glaucoma such as inter-species diversity, AI model generalizability and explainability, as well as AI applications using advanced ocular imaging and genomic data.

Changes in chorioretinal flow index after cataract surgery: an optical coherence tomography angiography study

PURPOSE

Pseudophakic cystoid macular edema (CME) occurs in up to 2% of uneventful cataract surgeries. This study evaluates changes in macular blood flow succeeding uneventful phacoemulsification cataract extraction among otherwise visually healthy subjects.

METHODS

This prospective study included 18 eyes of 18 patients undergoing routine phacoemulsification. Optical coherence tomography angiography (OCT-A) was performed using the Angio-Retina 6 × 6 mm protocol with the XR Avanti Angio-Vue system (Optovue Inc., Fremont, California) prior to the surgery and 4-8 weeks thereafter. Exclusion criteria included motion artifacts, segmentation errors and signal strength index (SSI) < 40. The main outcome measure was change in flow index (FI) measured in all 4 retinal segmentation layers within an area of 1 mm diameter around the foveal center.

RESULTS

Following surgery, a significant increase in SSI (46.65 ± 8.62 versus 53.12 ± 8.07, p = 0.01), superficial plexus FI (0.98 ± 0.23 versus 1.16 ± 0.16, p = 0.02) and deep plexus FI (0.54 ± 0.46 versus 0.93 ± 0.39, p = 0.01) was found. No significant changes were noted in the outer retina or the choriocapillaris.

CONCLUSION

The study demonstrates a significant increase in FI in the superficial and deep retinal plexus following uneventful cataract surgery, with the greatest changes occurring in the latter. These findings corroborate evidence from structural imaging and support the vascular etiology of pseudophakic CME.

Deep Capillary Nonperfusion on OCT Angiography Predicts Complications in Eyes with Referable Nonproliferative Diabetic Retinopathy

OBJECTIVE

To evaluate the ability of capillary nonperfusion parameters on OCT angiography (OCTA) to predict the development of clinically significant outcomes in eyes with referable nonproliferative diabetic retinopathy (NPDR).

DESIGN

Prospective longitudinal observational study.

SUBJECTS

In total, 59 patients (74 eyes) with treatment-naive moderate and severe (referable) NPDR.

METHODS

Patients were imaged with OCTA at baseline and then followed-up for 1 year. We evaluated 2 OCTA capillary nonperfusion metrics, vessel density (VD) and geometric perfusion deficits (GPDs), in the superficial capillary plexus, middle capillary plexus (MCP), and deep capillary plexus (DCP). We compared the predictive accuracy of baseline OCTA metrics for clinically significant diabetic retinopathy (DR) outcomes at 1 year.

MAIN OUTCOME MEASURES

Significant clinical outcomes at 1 year, defined as 1 or more of the following-vitreous hemorrhage, center-involving diabetic macular edema, and initiation of treatment with pan-retinal photocoagulation or anti-VEGF injections.

RESULTS

Overall, 49 patients (61 eyes) returned for the 1-year follow-up. Geometric perfusion deficits and VD in the MCP and DCP correlated with clinically significant outcomes at 1 year (P < 0.001). Eyes with these outcomes had lower VD and higher GPD, indicating worse nonperfusion of the deeper retinal layers than those that remained free from complication. These differences remained significant (P = 0.046 to < 0.001) when OCTA parameters were incorporated into models that also considered sex, baseline corrected visual acuity, and baseline DR severity. Adjusted receiver operating characteristic curve for DCP GPD achieved an area under the curve (AUC) of 0.929, with sensitivity of 89% and specificity of 98%. In a separate analysis focusing on high-risk proliferative diabetic retinopathy outcomes, MCP and DCP GPD and VD remained significantly predictive with comparable AUC and sensitivities to the pooled analysis.

CONCLUSIONS

Evidence of deep capillary nonperfusion at baseline in eyes with clinically referable NPDR can predict short-term DR complications with high accuracy, suggesting that deep retinal ischemia has an important pathophysiologic role in DR progression. Our results suggest that OCTA may provide additional prognostic benefit to clinical DR staging in eyes with high risk.

Dilated choroidal vascular channels in pachychoroid neovasculopathy

BACKGROUND

To elucidate the pattern of the choroidal vasculature in exudative pachychoroid neovasculopathy (PNV) and its correlation with the clinical course and treatment outcomes.

METHODS

The retrospective study included consecutive patients in National Taiwan University Hospital between 2014 and 2020 who fulfilled the criteria for exudative PNV defined as active type 1 macular neovascularization (MNV) on optical coherence tomography angiography (OCTA) and with leakage on fluorescein angiography (FA) or indocyanine green angiography (ICGA) associated with pachychoroid features. The corrected distance visual acuity (CDVA), FA, ICGA, and OCT images obtained by Optovue (Optovue Inc, Freemont CA, USA) spectral domain OCT were evaluated at baseline and various time points during the 12-month treatment period. The correlations between the choroidal vascular patterns, specifically those with or without dilated choroidal vascular channels (DCVC) revealed by ICGA, and baseline characteristics and treatment outcomes were evaluated using multiple regression models.

RESULTS

The study enrolled 34 eyes of 31 patients. The average age was 59.0 ± 9.3 years, and 20 participants were men. ICGA revealed DCVCs in 21 eyes, while the remaining 13 eyes did not have DCVCs. At baseline, DCVC group was older (p = 0.03) and had a longer duration of visual symptoms (p = 0.02), with a higher vessel density (defined as the percentage of the measured area occupied by flow area) of MNV (p = 0.04), higher proportion of ellipsoid zone disruption (p = 0.01), and poorer CDVA (p = 0.03). After the 12-month treatment period, the frequency of requirement of anti-VEGF injections (p < 0.01) was higher, and the risk for CDVA <20/40 was higher (adjusted OR: 5.29, 95% CI: 1.24-22.48, p = 0.02) in eyes with DCVCs.

CONCLUSIONS

For PNV, eyes with DCVCs were associated with higher vessel density of macular neovascularization and poorer CDVA at baseline, and had poorer visual and anatomical outcomes although more anti-VEGF injections were given.

Factors related to changes in visual symptoms after successful photodynamic therapy in central serous chorioretinopathy

To investigate biomarkers related to visual symptom and best corrected visual acuity (BCVA) improvement after photodynamic therapy (PDT) for central serous chorioretinopathy. This retrospective cross-sectional study involved 42 consecutive eyes, from 42 patients who underwent successful PDT, divided into two groups according to improvement in subjective visual complaints: complete (20 eyes) and incomplete recovery (22 eyes). The clinical characteristics of each group, including central foveal thickness (CFT), foveal avascular zone (FAZ) area, and degree of change in signal voiding of the choriocapillaris on optical coherence tomography angiography, were compared. Correlations between best-corrected visual acuity (BCVA) and baseline clinical features were investigated. At baseline, CFT and FAZ areas showed significant differences between the two groups (all p < 0.05). Multiple binary logistic regression analysis revealed that greater CFT predicted complete recovery from visual complaints (p = 0.002). Reduction or disappearance of signal voiding in the choriocapillaris 6 months post-PDT occurred more frequently in the complete recovery group (p < 0.05). FAZ area before PDT correlated with BCVA before and 6 months after PDT and BCVA improvement during the study period (all p < 0.05). CFT and FAZ area before PDT correlated with completeness of visual symptom recovery after PDT. Smaller FAZ area before PDT correlated with better BCVA before and after treatment.

Adaptive dynamic analysis-based optical coherence tomography angiography for blood vessel projection artifact suppression

Optical coherence tomography angiography (OCTA) for blood vessel 3-D structure imaging suffers from blood vessel projection artifacts/tail artifacts when using a long decorrelation time (e.g., repeat B-scan acquisition in regular OCTA) or loss of micro vessel signal when using a short decorrelation time. In this work, we developed an adaptive first-order field autocorrelation function (g₁) analysis-based technique to suppress the projection artifacts under macro vessels while enhancing the dynamic signal of micro vessels. The proposed method is based on the differences of the decorrelation rate and the phase variations of g₁ between the vessel voxels and the artifacts regions. A short or long decorrelation time was applied to obtain the dynamic index of the projection artifacts region or the blood vessel region, respectively. Compared to the slab subtraction-based post-image processing-based techniques, the proposed approach addresses this problem on a physical basis and shows the ability to suppress the projection artifacts while enhancing the detection of the micro vessels.

Deep learning-based signal-independent assessment of macular avascular area on 6×6 mm optical coherence tomography angiogram in diabetic retinopathy: a comparison to instrument-embedded software

SYNOPSIS

A deep-learning-based macular extrafoveal avascular area (EAA) on a 6×6 mm optical coherence tomography (OCT) angiogram is less dependent on the signal strength and shadow artefacts, providing better diagnostic accuracy for diabetic retinopathy (DR) severity than the commercial software measured extrafoveal vessel density (EVD).

AIMS

To compare a deep-learning-based EAA to commercial output EVD in the diagnostic accuracy of determining DR severity levels from 6×6 mm OCT angiography (OCTA) scans.

METHODS

The 6×6 mm macular OCTA scans were acquired on one eye of each participant with a spectral-domain OCTA system. After excluding the central 1 mm diameter circle, the EAA on superficial vascular complex was measured with a deep-learning-based algorithm, and the EVD was obtained with commercial software.

RESULTS

The study included 34 healthy controls and 118 diabetic patients. EAA and EVD were highly correlated with DR severity (ρ=0.812 and -0.577, respectively, both p<0.001) and visual acuity (r=-0.357 and 0.420, respectively, both p<0.001). EAA had a significantly (p<0.001) higher correlation with DR severity than EVD. With the specificity at 95%, the sensitivities of EAA for differentiating diabetes mellitus (DM), DR and severe DR from control were 80.5%, 92.0% and 100.0%, respectively, significantly higher than those of EVD 11.9% (p=0.001), 13.6% (p<0.001) and 15.8% (p<0.001), respectively. EVD was significantly correlated with signal strength index (SSI) (r=0.607, p<0.001) and shadow area (r=-0.530, p<0.001), but EAA was not (r=-0.044, p=0.805 and r=-0.046, p=0.796, respectively). Adjustment of EVD with SSI and shadow area lowered sensitivities for detection of DM, DR and severe DR.

CONCLUSION

Macular EAA on 6×6 mm OCTA measured with a deep learning-based algorithm is less dependent on the signal strength and shadow artefacts, and provides better diagnostic accuracy for DR severity than EVD measured with the instrument-embedded software.

Diminished choroidal blood flow in hypertensive and preeclamptic third trimester pregnancies using optical coherence tomography angiography

PURPOSE

The aim of this study was to compare choroidal adjusted flow index (AFI) in healthy, hypertensive & preeclamptic pregnancies using optical coherence tomography angiography (OCTA).

METHODS

In this prospective study, healthy, hypertensive & preeclamptic third trimester pregnant women underwent OCTA imaging. 3x3 & 6x6 mm choriocapillaris slabs were exported and the parafoveal area was marked by two concentric ETDRS circles at 1 & 3 mm, centered on the foveal avascular zone. Parafoveal AFI was calculated as a parameter of choroidal blood flow.

RESULTS

Fifteen eyes of fifteen women per group were recruited (45 eyes). AFI was significantly lower in the preeclamptic compared to the healthy & hypertensive groups (Tukey HSD: <0.001 in both groups on 3x3 mm, and 0.02 & 0.04 in 6x6 mm scans), and in the hypertensive compared to the healthy group (0.005 & 0.03 in 3x3 & 6x6 mm scans respectively).

CONCLUSIONS

Pregnancies complicated with preeclampsia revealed the lowest choroidal blood flow on OCTA followed by pregnancies with systemic hypertension compared to healthy pregnancies. We provide in-vivo documentation of choroidal ischemia, highlighting its culpability in hypertensive and preeclamptic retinochoroidal pathology, and the possibility of utilizing choroidal blood flow on OCTA as a precursor for disease progression.

[Optical coherence tomography and optical coherence tomography angiography for detecting glaucoma progression. Part 2. Clinical and functional correlations, monitoring of advanced glaucoma and limitations of the method]

The purpose of this study is to analyze the literature on the role of optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) in the diagnosis of glaucoma. This review considers the structural and functional correlations observed during the progression of glaucomatous optic neuropathy, as well as the capabilities of the method in late glaucoma, describes the strengths and weaknesses of OCT and OCTA, and pays particular attention to the role of OCT in assessing the effectiveness of treatment. Optical coherence tomography is the main method for determining the progression of glaucoma, which plays a key role in the choice of treatment algorithm. However, the use of OCT in far advanced glaucoma has certain particularities and limitations. OCTA can be helpful in overcoming this problem.

Detection of Stroke with Retinal Microvascular Density and Self-Supervised Learning Using OCT-A and Fundus Imaging

Acute cerebral stroke is a leading cause of disability and death, which could be reduced with a prompt diagnosis during patient transportation to the hospital. A portable retina imaging system could enable this by measuring vascular information and blood perfusion in the retina and, due to the homology between retinal and cerebral vessels, infer if a cerebral stroke is underway. However, the feasibility of this strategy, the imaging features, and retina imaging modalities to do this are not clear. In this work, we show initial evidence of the feasibility of this approach by training machine learning models using feature engineering and self-supervised learning retina features extracted from OCT-A and fundus images to classify controls and acute stroke patients. Models based on macular microvasculature density features achieved an area under the receiver operating characteristic curve (AUC) of 0.87-0.88. Self-supervised deep learning models were able to generate features resulting in AUCs ranging from 0.66 to 0.81. While further work is needed for the final proof for a diagnostic system, these results indicate that microvasculature density features from OCT-A images have the potential to be used to diagnose acute cerebral stroke from the retina.

A comprehensive update on the use of optical coherence tomography angiography in glaucoma

PURPOSE

The primary purpose of this review is to provide a comprehensive summary on the technical principles of OCTA and to enumerate vascular parameters being explicated for glaucoma diagnosis and progression with emphasis on recent studies. In addition, the authors also summarize the future clinical potentials of OCTA in glaucoma and enumerate the limitations of this imaging modality in the present-day scenario.

METHODS

The index study is a narrative review on OCTA in glaucoma. The authors searched the PubMed database using the key phrases ''optical coherence tomography angiography" AND "glaucoma,'' AND/OR "vascular parameters" AND/OR "ocular perfusion." Being a relatively recent development in ocular imaging, studies in which OCTA imaging had been used for glaucoma evaluation since 2012 were included until March 2022. The literature search included original studies and previous review articles, while case reports were excluded. Preliminary search was based on relevant articles with search keywords in the title and abstract. The second screening was performed by reading the full text of the literature.

RESULTS

Recent studies indicate reduction in microcirculation in glaucomatous eyes compared to the normal subjects. The area of interest for glaucoma evaluation using OCTA varies among the different studies. Based on the literature reviewed here, (1) OCTA parameters measured in the peripapillary; ONH and macular area have been shown to differentiate between glaucoma and normal eyes with a discriminatory power comparable to OCT parameters used routinely in clinics, (2) monitoring of peripapillary and macular vessel density may provide important information to the evaluation of glaucoma progression and prediction of rates of disease worsening, (3) studies suggest strong correlation between the OCTA parameters, the OCT parameters and visual function, measured by visual field testing, in glaucomatous eyes, (4) future prospects of OCTA in glaucoma evaluations using AI predicting structural and functional features and prognosis based on early vascular findings would open up scope for early detection of high-risk suspects and fast progressors in glaucoma.

CONCLUSION

OCTA can be useful in quantifying vascular parameters in the optic disc, peripapillary and the macular regions for glaucoma evaluation. OCTA shows potential to become a part of everyday glaucoma management.

Optical Coherence Tomography Angiography (OCTA) of the eye: A review on basic principles, advantages, disadvantages and device specifications

Optical Coherence Tomography Angiography (OCTA) is a relatively new imaging technique in ophthalmology for the visualization of the retinal microcirculation and other tissues of the human eye. This review paper aims to describe the basic definitions and principles of OCT and OCTA in the most straightforward possible language without complex mathematical and engineering analysis. This is done to help health professionals of various disciplines improve their understanding of OCTA and design further clinical research more efficiently. First, the basic technical principles of OCT and OCTA and related terminology are described. Then, a list of OCTA advantages and disadvantages, with a special reference to blood flow quantification limitations. Finally, an updated list of the basic hardware and software specifications of some of the commercially available OCTA devices is presented.

Morphological changes in retinochoroidal microvasculature after caffeinated versus decaffeinated coffee consumption

BACKGROUND

To investigate changes in retinochoroidal microvascular morphology after caffeinated versus decaffeinated coffee consumption in age- and gender-matched healthy individuals using optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

In this prospective, randomized clinical study, a staff member in charge of record keeping randomly assigned 48 healthy volunteers to two groups: caffeinated coffee consumers (24 eyes) and decaffeinated coffee consumers (24 eyes). Participants' ages and genders were recorded before consumption, and a comprehensive ophthalmologic exam was performed, followed by OCT and OCTA analyses before, 30 min, one, six, and 24 h after blindly consuming either of the coffees.

RESULTS

Caffeinated and decaffeinated coffee consumers had mean ages of 23.45 ± 0.92 and 22.73 ± 1.13, respectively (p = 0.407). The following parameters changed significantly in caffeinated coffee consumers 30 min and 1 h post-consumption (pre-consumption versus 30 min versus one hour post-consumption; p < 0.05): a) parafoveal superficial capillary plexus vessel density (%): 54.45 versus 51.8 versus 51.92, b) parafoveal deep capillary plexus vessel density (%): 55.16 versus 52.45 versus 52.83, c) outer retinal flow area (%): 8.87 ± 1.91 versus 8.03 ± 1.88 versus 8.11 ± 1.93, d) choriocapillaris flow area (mm²): 20.95 ± 0.98 versus 19.82 ± 1.20 a versus 19.62 ± 0.95, and e) sub-foveal choroidal thickness (µm): 295.06 ± 5.45 versus 277.08 ± 5.33 versus 260.71 ± 58.61. No significant differences in any OCT and OCTA parameters were found between consecutive measurements in decaffeinated coffee consumers (p > 0.05).

CONCLUSIONS

Caffeinated coffee appears to transiently reduce parafoveal vessel density, capillary flow area, and sub-foveal choroidal thickness. Lack of these microvascular morphological changes in decaffeinated coffee suggests a potential caffeine-induced vasoconstrictive effect.

Study of choroidal vasculature in open angle glaucoma patients

PURPOSE

To investigate the vessel density (VD) of the choriocapillary (CC) plexus in patients affected by preperimetric glaucoma (PPG), advanced glaucoma (AG) and in a healthy control group using Optical Coherence Tomography Angiography (OCTA) in order to clarify the pathogenetic mechanisms of this disease.

METHODS

In this prospective observational study, 19 eyes from 19 patients affected by preperimetric glaucoma (PPG) and 18 eyes from 18 patients affected by advanced glaucoma were studied from January 2022 to May 2022 at the University of Naples "Federico II". These patients had been compared with 20 eyes of 20 healthy subjects that represented the control group. All subjects underwent EDI-OCT to assess the subfoveal choroidal thickness (SFCT). OCTA was used to evaluate the vessel density (VD) of the CC in whole image in the studies groups.

RESULTS

The PPG and AG groups showed a statistically significant reduction in CC vessel density parameters with respect to controls (p < 0.001). Regarding EDI OCT results AG patients exhibited a statistically significant increase in the SFCT compared to healthy controls (p < 0.001). Whereas,no statistically significant difference was between the PPG groups and to healthy controls (p 0.851).

CONCLUSIONS

CC vessel density could represent a helpful and sensible biomarker to identify early choroidal microvascular changes in PPG and MCI in order to better understand the vascular pathophysiological mechanisms involved in glaucoma diseases.

Insights into Sickle Cell Disease through the Retinal Microvasculature: Adaptive Optics Scanning Light Ophthalmoscopy Correlates of Clinical OCT Angiography

PURPOSE

Clinical OCT angiography (OCTA) of the retinal microvasculature offers a quantitative correlate to systemic disease burden and treatment efficacy in sickle cell disease (SCD). The purpose of this study was to use the higher resolution of adaptive optics scanning light ophthalmoscopy (AOSLO) to elucidate OCTA features of parafoveal microvascular compromise identified in SCD patients.

DESIGN

Case series of 11 SCD patients and 1 unaffected control.

PARTICIPANTS

A total of 11 eyes of 11 SCD patients (mean age, 33 years; range, 23-44; 8 female, 3 male) and 1 eye of a 34-year-old unaffected control.

METHODS

Ten sequential 3 × 3 mm parafoveal OCTA full vascular slab scans were obtained per eye using a commercial spectral domain OCT system (Avanti RTVue-XR; Optovue). These were used to identify areas of compromised perfusion near the foveal avascular zone (FAZ), designated as regions of interest (ROIs). Immediately thereafter, AOSLO imaging was performed on these ROIs to examine the cellular details of abnormal perfusion. Each participant was imaged at a single cross-sectional time point. Additionally, 2 of the SCD patients were imaged prospectively 2 months after initial imaging to study compromised capillary segments across time and with treatment.

MAIN OUTCOME MEASURES

Detection and characterization of parafoveal perfusion abnormalities identified using OCTA and resolved using AOSLO imaging.

RESULTS

We found evidence of abnormal blood flow on OCTA and AOSLO imaging among all 11 SCD patients with diverse systemic and ocular histories. Adaptive optics scanning light ophthalmoscopy imaging revealed a spectrum of phenomena, including capillaries with intermittent blood flow, blood cell stasis, and sites of thrombus formation. Adaptive optics scanning light ophthalmoscopy imaging was able to resolve single sickled red blood cells, rouleaux formations, and blood cell-vessel wall interactions. OCT angiography and AOSLO imaging were sensitive enough to document improved retinal perfusion in an SCD patient 2 months after initiation of oral hydroxyurea therapy.

CONCLUSIONS

Adaptive optics scanning light ophthalmoscopy imaging was able to reveal the cellular details of perfusion abnormalities detected using clinical OCTA. The synergy between these clinical and laboratory imaging modalities presents a promising avenue in the management of SCD through the development of noninvasive ocular biomarkers to prognosticate progression and measure the response to systemic treatment.

Optical coherence tomographic angiography detects retinal vascular changes associated with pituitary adenoma

Purpose

Observations

Conclusions and importance

Deep Capillary Geometric Perfusion Deficits on OCT Angiography Detect Clinically Referable Eyes with Diabetic Retinopathy

PURPOSE

To evaluate the sensitivity (SN) and specificity (SP) of OCT angiography (OCTA) parameters for detecting clinically referable eyes with diabetic retinopathy (DR) in a cohort of patients with diabetes mellitus (DM).

DESIGN

Retrospective, cross-sectional study.

SUBJECTS

Patients with DM with various levels of DR.

METHODS

We measured vessel density, vessel length density (VLD), and geometric perfusion deficits (GPDs) in the full retina, superficial capillary plexus (SCP), and deep capillary plexus (DCP) on 3 × 3-mm OCTA images. Geometric perfusion deficit was recently described as retinal tissue located further than 30 μm from blood vessels, excluding the foveal avascular zone (FAZ). We modified the GPD metric by including the FAZ as an additional variable. Clinically referable eyes were defined as moderate nonproliferative DR (NPDR) or worse retinopathy, or diabetic macular edema (DME). One eye from each patient was selected for the analysis based on image quality. We used a binary logistic regression model to adjust for covariates.

MAIN OUTCOME MEASURES

Sensitivity, SP, and area under the curve (AUC).

RESULTS

Seventy-one of 150 included eyes from 150 patients (52 with DM without DR, 27 with mild NPDR, 16 with moderate NPDR, 10 with severe NPDR, 30 with proliferative DR, and 15 with DME) had clinically referable DR. Geometric perfusion deficit metric that included the FAZ performed better than GPD in detecting referable DR in the SCP (P = 0.025) but not the DCP or full retina (P > 0.05 for both). Deep capillary plexus GPD had the largest AUC for detecting clinically referable eyes (AUC = 0.965, SN = 97.2%, SP = 84.8%), which was significantly larger than the AUC for vessel density of any layer (P < 0.05 for all) but not DCP VLD (P = 0.166). The cutoff value of 2.5% for DCP GPD resulted in a highly sensitive test for detecting clinically referable eyes without adjusting for covariates (AUC = 0.955, SN = 97.2%, SP = 79.7%).

CONCLUSIONS

Vascular parameters in OCTA, especially in the DCP, have the potential to identify eyes that warrant further evaluation. Geometric perfusion deficits may better distinguish these clinically referable eyes with DR than standard vessel density parameters.

The Effect of Pathological Retinal Changes on Retinal Capillary Circulation in Myopic Patients

Objectives

Myopia is a common ocular disorder worldwide, leading to degenerative changes in the retina which is highly susceptible to vascular impairment. The aim of the study was to investigate the effects of pathological retinal changes on the retinal capillary structures using optical coherence tomography angiography (OCTA) in myopic patients.

Methods

Thirty-two patients with high myopia (HM), 29 patients with pathological myopia (PM), and 38 healthy subjects with emmetropia (EM) were enrolled in this study. OCTA was performed to measure the following parameters: Foveal avascular zone (FAZ) area; FAZ perimeter; FAZ acircularity index (AI); and superficial, deep, and radial peripapillary capillary (RPC) vessel densities. Axial length (AL), spherical equivalent, and anterior chamber depth were evaluated.

Results

Significant differences in the mean AL values were observed between the EM group and the other groups (p<0.001 for all); however, no significant differences were observed between the HM and PM groups (p=0.135). Significant differences in FAZ parameters, except for AI, were found among the three groups (p<0.05 for all). In all regions, except for the fovea and inside disc, the capillary plexus vessel densities were significantly lower in the PM group than in the other groups and were lower in the HM group than in the EM group (p<0.05 for all).

Conclusion

Significant differences identified in capillary densities between the HM and PM groups, both of which present similar AL measurements, suggest that pathological retinal findings have significant effects on retinal perfusion independent of the effect of AL.

Macrophage-like Cells Are Increased in Patients with Vision-Threatening Diabetic Retinopathy and Correlate with Macular Edema

Macrophage-like cells (MLCs) are potential inflammatory biomarkers. We previously showed that MLCs are increased in proliferative diabetic retinopathy (PDR) eyes. Vision-threatening diabetic retinopathy (VTDR) includes PDR, severe non-PDR (NPDR), and diabetic macular edema (DME). No prior data exist on MLCs in eyes with severe NPDR or DME. This prospective, cross-sectional optical coherence tomography-angiography (OCT-A) imaging study included 40 eyes of 37 participants who had NPDR classified as non-VTDR (n = 18) or VTDR (n = 22). Repeated OCT-A images were registered, averaged, and used to quantify the main outcome measures: MLC density and percent area. MLC density and percent area were correlated with clinical characteristics, NPDR stage, presence of DME, and OCT central subfield thickness (CST). In VTDR eyes, MLC density (2.6-fold, p < 0.001) and MLC percent area (2.5-fold, p < 0.01) were increased compared with non-VTDR eyes. Multiple linear regression analysis between MLC metrics and clinical characteristics found that MLC density was positively correlated with worse NPDR severity (p = 0.023) and higher CST values (p = 0.010), while MLC percent area was only positively associated with increased CST values (p = 0.006). MLCs are increased in patients with VTDR. Macular edema is the most strongly associated factor with increased MLC numbers in NPDR eyes.

Visual function and disability are associated with microcystic macular edema, macular and peripapillary vessel density in patients with neuromyelitis optica spectrum disorder

Purpose

To assess macular and peripapillary vessel density and neurodegeneration in eyes with and without microcystic macular edema (MME) in neuromyelitis optica spectrum disorder (NMOSD) patients while investigating their association with visual impairment and disease disability.

Methods

This is a cross-sectional study. A total of 52 eyes from 29 NMOSD patients were recruited, including 8 eyes with MME from 7 patients. Optical coherence tomography angiography (OCTA) images were analyzed to quantify the radial papillary capillary density (RPCD), and the density of macular microvascular network in both the superficial retinal capillary plexus (SRCP) and the deep retinal capillary plexus (DRCP). Thicknesses of the neural retinal layers centered on the fovea and the optic nerve head were also collected by OCT. Best-corrected visual acuity (BCVA) and Expanded Disability Status Scale (EDSS) scores were assessed for all patients. Microvascular densities and retinal sublayer thicknesses were compared among groups, and correlations of these vascular and structural parameters with BCVA and EDSS scores were determined.

Results

Patients with NMOSD and MME had significantly decreased visual acuity and worse EDSS score than patients without MME (P = 0.01 and 0.002, respectively). The vessel density in SRCP and RPCD were significantly lower in eyes with MME and ON compared to that of eyes with ON but without MME and eyes without MME or ON. Impairment of visual acuity and disease severity were significantly negatively associated with the reduction of SRCP vessel density and RPCD but were not related to DRCP vessel density.

Conclusions

MME were correlated with worse visual impairment and disability in NMOSD patients. Sparse SRCP vessel density and RPCD were observed in NMOSD MME eyes and correlated with worse BCVA and EDSS scores.

Deep-Learning-Aided Diagnosis of Diabetic Retinopathy, Age-Related Macular Degeneration, and Glaucoma Based on Structural and Angiographic OCT

Purpose

Timely diagnosis of eye diseases is paramount to obtaining the best treatment outcomes. OCT and OCT angiography (OCTA) have several advantages that lend themselves to early detection of ocular pathology; furthermore, the techniques produce large, feature-rich data volumes. However, the full clinical potential of both OCT and OCTA is stymied when complex data acquired using the techniques must be manually processed. Here, we propose an automated diagnostic framework based on structural OCT and OCTA data volumes that could substantially support the clinical application of these technologies.

Design

Cross sectional study.

Participants

Five hundred twenty-six OCT and OCTA volumes were scanned from the eyes of 91 healthy participants, 161 patients with diabetic retinopathy (DR), 95 patients with age-related macular degeneration (AMD), and 108 patients with glaucoma.

Methods

The diagnosis framework was constructed based on semisequential 3-dimensional (3D) convolutional neural networks. The trained framework classifies combined structural OCT and OCTA scans as normal, DR, AMD, or glaucoma. Fivefold cross-validation was performed, with 60% of the data reserved for training, 20% for validation, and 20% for testing. The training, validation, and test data sets were independent, with no shared patients. For scans diagnosed as DR, AMD, or glaucoma, 3D class activation maps were generated to highlight subregions that were considered important by the framework for automated diagnosis.

Main Outcome Measures

The area under the curve (AUC) of the receiver operating characteristic curve and quadratic-weighted kappa were used to quantify the diagnostic performance of the framework.

Results

For the diagnosis of DR, the framework achieved an AUC of 0.95 ± 0.01. For the diagnosis of AMD, the framework achieved an AUC of 0.98 ± 0.01. For the diagnosis of glaucoma, the framework achieved an AUC of 0.91 ± 0.02.

Conclusions

Deep learning frameworks can provide reliable, sensitive, interpretable, and fully automated diagnosis of eye diseases.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

A two-year longitudinal study of retinal vascular impairment in patients with amnestic mild cognitive impairment

Objective

To evaluate the relation between retinal vascular impairment and cognitive decline in patients with amnestic mild cognitive impairment (aMCI) over time.

Methods

Spectral domain-optical coherence tomography (SD-OCT) and OCT angiography study was performed in aMCI patients over 2 years follow-up and compared to baseline.

Results

Thirty-eight eyes from 19 aMCI patients were evaluated. Structural and vascular OCT measures were reduced at follow-up except for vessel density (VD) of the choriocapillaris, unchanged, and foveal avascular zone, which was increased; no changes in any parameter were found in 18 age-matched healthy controls. Overall, these findings were confirmed when patients were evaluated separately according to progression to dementia. Only non-converters to dementia showed significant VD reduction in the deep capillary plexuses (coeff. β = −4.20; p &lt; 0.001), may be for an initial massive VD depletion becoming less evident with progression of the disease. MMSE reduction was associated with a higher ganglion cell complex reduction (coeff. β = 0.10; p = 0.04) and a higher VD reduction in the radial peripapillary capillary (RPC) plexus (coeff. β = 0.14; p = 0.02) in the whole patient group, while it was associated with a higher VD reduction only in RPC plexus in converters (coeff. β = 0.21; p &lt; 0.001).

Conclusion

Our data shows vascular impairment progression in the inner retina of aMCI patients and support the hypothesis that vascular changes may contribute to the onset and progression of Alzheimer’s disease. Other follow-up studies, with a larger number of patients, are needed to better define VD as a potential biomarker.

Clinically Significant Nonperfusion Areas on Widefield OCT Angiography in Diabetic Retinopathy

Purpose

To investigate the distribution of clinically significant nonperfusion areas (NPAs) on widefield OCT angiography (OCTA) images in patients with diabetes.

Design

Prospective, cross-sectional, observational study.

Participants

One hundred and forty-four eyes of 114 patients with diabetes.

Methods

Nominal 20 × 23 mm OCTA images were obtained using a swept-source OCTA device (Xephilio OCT-S1), followed by the creation of en face images 20-mm (1614 pixels) in diameter centering on the fovea. The nonperfusion squares (NPSs) were defined as the 10 × 10 pixel squares without retinal vessels, and the ratio of eyes with the NPSs to all eyes in each square was referred to as the NPS ratio. The areas with probabilistic differences (APD) for proliferative diabetic retinopathy (PDR) and nonproliferative diabetic retinopathy (NPDR) (APD[PDR] and APD[NPDR]) were defined as sets of squares with higher NPS ratios in eyes with PDR and NPDR, respectively. The P ratio (NPSs within APD[PDR] but not APD[NPDR]/all NPSs) was also calculated.

Main Outcome Measures

The probabilistic distribution of the NPSs and the association with diabetic retinopathy (DR) severity.

Results

The NPSs developed randomly in eyes with mild and moderate NPDR and were more prevalent in the extramacular areas and the temporal quadrant in eyes with severe NPDR and PDR. The APD(PDR) was distributed mainly in the extramacular areas, sparing the areas around the vascular arcades and radially peripapillary capillaries. The APD(PDR) contained retinal neovascularization more frequently than the non-APD(PDR) (P = 0.023). The P ratio was higher in eyes with PDR than in those with NPDR (P < 0.001). The multivariate analysis designated the P ratio (odds ratio, 8.293 × 10⁷; 95% confidence interval, 6.529 × 10²-1.053 × 10¹³; P = 0.002) and the total NPSs (odds ratio, 1.002; 95% confidence interval, 1.001-1.003; P < 0.001) as independent risk factors of PDR. Most eyes with NPDR and 4-2-1 rule findings of DR severity had higher P ratios but not necessarily greater NPS numbers.

Conclusions

The APD(PDR) is uniquely distributed on widefield OCTA images, and the NPA location patterns are associated with DR severity, independent of the entire area of NPAs.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Multipressure Dial Goggle Effects on Circumpapillary Structure and Microvasculature in Glaucoma Patients

PURPOSE

To evaluate the effects of pressure changes induced by a multipressure dial (MPD) on circumpapillary retinal nerve fiber layer (RNFL) and capillary density (CD) measurements in patients with glaucoma using OCT angiography (OCTA).

DESIGN

Prospective interventional study.

PARTICIPANTS

Twenty-four patients with primary open-angle glaucoma.

METHODS

One eye of each patient underwent negative pressure application with the MPD. The MPD alters intraocular pressure (IOP) relative to atmospheric pressure by generating a negative pressure vacuum within a goggle chamber that is placed over the eye. Each participant underwent serial high density OCTA imaging (AngioVue) of the optic nerve head at different negative pressure increments of -5 mmHg, starting from 0 mmHg, ending at -20 mmHg, and then returning to baseline. Images were acquired after 2 minutes of sustained negative pressure at each target pressure to allow for stabilization of the retinal structures and microvasculature. The RNFL thickness and CD measurements were automatically calculated using the native AngioVue software, and then exported for analysis.

MAIN OUTCOME MEASURES

The influence of different levels of negative pressure on circumpapillary RNFL thickness and CD measurements, assessed by a linear mixed-effects model with repeated measures.

RESULTS

The mean (± SD) age was 71.0 years (± 7.8 years), the baseline IOP was 17.5 mmHg (± 3.6 mmHg), and there was a mean 24-2 mean deviation of -2.80 dB (± 2.55 dB). Serial circumpapillary CD measurements showed a statistically significant dose-dependent increase from baseline, without negative pressure application, to the maximum negative pressure application of -20 mmHg (difference, 2.27%; P = 0.010). Capillary density measurements then decreased symmetrically when lowering the negative pressure to baseline. Circumpapillary CD measurements at target negative pressures of -10 mmHg, -15 mmHg, and -20 mmHg were significantly higher than the baseline measurements (all P values < 0.05). Circumpapillary RNFL thickness remained the same throughout different levels of negative pressure.

CONCLUSIONS

Circumpapillary CD measurements showed a dose-dependent increase with the induction of negative pressure, while RNFL thickness measurements remained unchanged.

Correlation analysis between foveal avascular zone and near peripheral retinal hypoperfusion in multiple sclerosis: a wide field optical coherence tomography angiography study

The identification of non-invasive biomarkers to investigate and monitor retinal structural and vascular changes in multiple sclerosis (MS) represents an interesting source of debate. Until now optical coherence tomography angiography (OCTA) evaluated the foveal avascular zone (FAZ) and areas of retinal non-perfusion only in the macular region in MS patients. It could be interesting to identify possible biomarkers, useful in assessing the ischemic areas also in the near peripheral retina, since FAZ enlargement and the areas of peripheral retinal non-perfusions share common pathogenic processes. In this cross-sectional study, we investigated the correlation between the FAZ area and retinal vessel density (VD) in the near peripheral retina by new wide-field optical coherence tomography angiography (OCTA) in patients affected by relapsing-remitting multiple sclerosis (RR-MS). Moreover, we compared the FAZ area and the VD of superficial and deep capillary plexuses in the fovea region and in the near peripheral retina (6.4 × 6.4 mm) between RR-MS patients and healthy controls by means of a Solix full-range OCTA. Last, we also detected the changes in structural OCT parameters (ganglion cell complex and retinal nerve fiber layer). Thirty-three eyes of 33 RR-MS patients and 35 eyes of 35 healthy controls were enrolled. RR-MS patients showed a lower VD in the superficial capillary plexus and a significant increase in the FAZ area compared with controls. The deep capillary plexus revealed a reduced VD although not statistically significant in patients with respect to controls. In the patients' group, the FAZ area showed significantly negative correlations with VD of superficial capillary plexuses in the foveal and whole region, while the FAZ area did not negatively correlate with the VD of the deep capillary plexus. The significant correlations among OCTA parameters could demonstrate the FAZ area as a possible biomarker for assessing the perfusion status in the near peripheral retina, useful in RR-MS management. These findings could confirm the role of vascular dysfunction in the pathogenetic mechanisms of MS.

OCT-A in chronic central serous chorioretinopathy treated with oral eplerenone and half-fluence photodynamic therapy: A comparative study

PURPOSE

To evaluate retinal and choriocapillary vessel density (VD) changes in patients with chronic central serous chorioretinopathy (CSC) treated with half-fluence verteporfin photodynamic therapy (vPDT) or eplerenone, using optical coherence tomography angiography (OCTA).

METHODS

Patients affected by CSC and treated with vPDT and eplerenone were retrospectively studied. At baseline and 3 months after each treatment, all patients underwent a complete ophthalmological examination, including an evaluation of best-corrected visual acuity (BCVA), slit-lamp biomicroscopy, fundus examination, fluorescein angiography (FA), indocyanine green angiography (ICGA), spectral-domain optical coherence tomography (SD-OCT) and OCTA.

RESULTS

Forty-eight eyes of patients with CSC were analysed. Twenty-four eyes were placed in the vPDT group, and 24 eyes formed the eplerenone group. In both groups, OCTA showed a significant improvement in the VD of deep capillary plexus (DCP) and choriocapillaris (CC) after treatments with respect to baseline (p < 0.001), whereas the VD of superficial capillary plexus (SCP) did not show significant differences (p > 0.05). The PDT group demonstrated a statistically significant increase in the VD of DCP and CC with respect to the eplerenone group (DCP p = 0.012; CC p = 0.004). A statistically significant reduction with respect to baseline in subfoveal choroidal thickness (SFCT) (p = 0.001 for vPDT group; p = 0.001 for eplerenone group) and in central foveal thickness (CFT) (p = 0.001 for vPDT group; p = 0.001 for eplerenone group) was also found. The SFCT was significantly thinnest in the PDT group with respect to the eplerenone group (p = 0.021).

CONCLUSION

OCTA allowed us to study retinal and choriocapillary vascular changes in patients with CSC treated with vPDT and eplerenone.

Hemodynamic Effects of Anti-Vascular Endothelial Growth Factor Injections on Optical Coherence Tomography Angiography in Diabetic Macular Edema Eyes

Purpose

To evaluate retinal hemodynamic responses to anti-vascular endothelial growth factor (VEGF) injection in eyes with diabetic macular edema using optical coherence tomography angiography (OCTA). We performed a comparison of two different thresholding methods to identify the most accurate for studying the vessel density (VD) in diabetic macular edema eyes.

Methods

The study prospectively included 26 eyes of 22 subjects (aged 60.2 ± 13.7 years) who underwent OCTA scan before and after anti-VEGF injection (mean interval between OCTA = 31.1 ± 17.3 days). We analyzed adjusted flow index, VD, and Skeletonized vessel length density in the parafoveal area (3-mm annulus with a 1-mm inner circle), along with full-thickness fovea avascular zone area and central foveal thickness (CFT). Using averaged scans VD as the ground truth, we compared two different algorithms for VD at the different plexuses. Longitudinal changes were assessed using a generalized linear model correcting for central foveal thickness and Q-score.

Results

We found significantly decreased adjusted flow index in the DCP layer (P = 0.010) at the follow-up. Furthermore, foveal avascular zone (P < 0.001) and central foveal thickness (P = 0.003) showed significant decrease on follow-up compared with baseline. Comparing the thresholding algorithms showed that vessel length density-based thresholding was more accurate for quantifying the DCP VD.

Conclusions

The adjusted flow index decreased significantly in the DCP layer on follow-up OCTA scan, suggesting vascular flow disruption and decreased deep retinal perfusion after anti-VEGF injection. Our results also highlight the fact that the choice of thresholding method is particularly critical for DCP quantification in eyes with diabetic macular edema.

Translational Relevance

Findings confirmed impaired deep retinal capillary flow after anti-VEGF injection.

Repeatability of Choroidal Thickness Measurements in Healthy Subjects using RTVue XR Optical Coherence Tomography

Purpose

To determine the intrasession, intraobserver, interobserver, and repeatability of choroidal thickness measurements in the healthy subjects imaged on enhanced depth imaging system of RTVue XR spectral domain optical coherence tomography (OCT).

Methods

In this prospective, cross-sectional study, seventy eyes of 70 healthy volunteers with no known ocular disease were imaged using high-density scanning protocol of RTVue XR OCT. In a single imaging session, three sequential 12 mm macular-enhanced depth horizontal line scans were obtained through the fovea. Two experienced examiners measured the subfoveal choroidal thickness (SFCT), choroidal thickness at 500 μm nasally and temporally from the fovea in all the eyes, using the manual calipers provided in the software. The graders were masked to each other's measurement readings. The coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were used to measure the reliability within graders. Intergrader variability was assessed using Bland-Altman method and 95% limits of agreement (LoA).

Results

Intragrader CR for grader one was 4.11 μm (95% confidence interval [CI], -2.84-11.06) for SFCT and 5.73 μm (95% CI, -3.71-15.16) for the grader two. Intragrader ICC of grader one ranged from 0.996 for SFCT to 0.994 for temporal choroidal thickness. Intragrader ICC of grader two ranged from 0.993 for temporal choroidal thickness to 0.991 for SFCT. Intergrader CR ranged from 5.24 μm (95% CI, -4.66-15.15) for SFCT to 5.89 μm (95% CI, -7.27-19.04) for temporal choroidal thickness. Intergrader 95% LoA for SFCT, nasal and temporal choroidal thickness were, -15.84-12.15 μm, -15.99-17.7 μm, and - 19.12-15.57 μm, respectively.

Conclusion

Choroidal thickness measurements can be quantified with good repeatability using RTVue XR OCT, which would be useful in patients with chorioretinal diseases.

Age-related assessment of foveal avascular zone and surrounding capillary networks with swept source optical coherence tomography angiography in healthy eyes

AIM

To assess the macular capillary networks and foveal avascular zone (FAZ) with swept-source optical coherence tomography angiography in healthy eyes.

METHODS

This cross-sectional, prospective, observational study enrolled 222 eyes of 116 healthy participants with no ocular or systemic disease. SS-OCTA images were captured using the PLEX Elite 9000 (Carl Zeiss Meditec Inc., Dublin, CA, USA) with a 6 × 6 mm pattern centered on the foveal center. Vessel length density (VLD), perfusion density (PD), and FAZ parameters were analyzed using the manufacturer's automated software.

RESULTS

A significant negative correlation was observed between age and average VLD in the superficial plexus, and average PD in both the superficial plexus and the whole retina. A significant positive correlation between age and foveal avascular zone perimeter and area was also noted. Age-wise comparisons showed a trend for an increase in VLD and PD until 40 years of age, with a subsequent decrease in the older age in the macular region. The central subfield showed a decrease in the vessel density measurements in the 21-40 age group. FAZ area and perimeter were the mirror inverse of the central subfield vessel density measurements with a numerically greater area and perimeter in the 21-40 age group compared to the 0-20 and 41-60 age groups. FAZ circularity was significantly reduced after 40 years of age.

CONCLUSION

Age-related changes in the vessel density and FAZ parameters in the healthy macula are complex and vary with the macular location. These results carry significance when interpreting the data from diseased eyes.

Wide-field sensorless adaptive optics swept-source optical coherence tomographic angiography in rodents

In this study, we present a sensorless adaptive optics swept-source optical coherence tomographic angiography (sAO-SS-OCTA) imaging system for mice. Real-time graphics processing unit (GPU)-based OCTA image acquisition and processing software were applied to guide wavefront correction using a deformable mirror based on signal strength index (SSI) from both OCT and OCTA images. High-resolution OCTA images with aberrations corrected and contrast enhanced were successfully acquired. Fifty-degree field of view high-resolution montaged OCTA images were also acquired.

Recent advances in optical coherence tomography for anterior segment imaging in small animals and their clinical implications

Anterior segment optical coherence tomography (AS-OCT) is a rapidly evolving area of OCT imaging, providing high-resolution and non-invasive volumetric imaging of the anterior segment. This review focuses on recent advances in AS-OCT imaging in small animals, which we categorize into ultrahigh-resolution, spectroscopic, magnetomotive, polarization-sensitive, and angiographic AS-OCTs. We summarize their technical foundations, review their applications to small animal imaging, and briefly discuss their current and future clinical applications.

Brolucizumab Intravitreal Injection in Macular Neovascularization Type 1: VA, SD-OCT, and OCTA Parameter Changes during a 16-Week Follow-Up

INTRODUCTION

The aim of this study was to assess early anatomical and functional changes after brolucizumab intravitreal injection (BIVI) in patients with age-related macular degeneration (AMD) and macular neovascularization type 1 (MNV1).

METHODS

A total of 24 eyes of 24 patients suffering from naïve AMD with MNV1 candidates to BIVI as per label with q12/q8 dosing regimen after the loading dose were enrolled in this prospective study. Main outcome measures during a 16-week follow-up period included changes in best corrected visual acuity (BCVA), central macular thickness (CMT), subfoveal subretinal fluid (SSRF) thickness (SSRFT), subfoveal sub-retinal pigment epithelium (RPE) fluid thickness (SSRPEFT), subfoveal choroidal thickness (SFCT), and pigment epithelial detachment (PED) maximum height (PED-MH). In addition, MNV1 flow area; percentages of eyes with intraretinal fluid (IRF), subretinal fluid, and sub-RPE fluid at different time points; and percentages of eyes candidates to a q8 or q12 injection interval after disease activity assessment at week 16 were evaluated.

RESULTS

BCVA improved significantly from baseline (T0) to week 12 (T3) (p = 0.028). CMT showed a significant reduction from 456 ± 123 µm at T0 to 265 ± 85 µm at T3 (p < 0.001). SSRFT and SSRPEFT reduced significantly as well (p < 0.001 and p = 0.049, respectively). PED-MH and SFCT reduced significantly at the different time points (p = 0.020; p = 0.006, respectively). IRF presence changed significantly from 41.7% of eyes at T0 to 20.8% at T3 (p = 0.045). SSRF reduced significantly during follow-up, being present in 62.5% of eyes at T0 and 4.2% of eyes at T3 (p < 0.001). Subfoveal sub-RPE fluid decreased significantly during time, being present in 20.8% of eyes at T0 and 0% at T3 (p = 0.013). Most of the eyes (18 eyes, 75%) at week 16 after disease activity assessment were shifted in the q12 interval, and only a minority of eyes shifted in a q8 interval (6 eyes, 25%).

CONCLUSION

Brolucizumab is efficient in AMD patients with MNV1 by reducing all retinal fluids during the loading phase and shows reduction of macular thickness, choroidal thickness, and PED height. Most eyes at disease activity assessment (75%) fall into 12-week interval and the minority (25%) into the 8-week interval.