Optical Coherence Tomography Angiograms Research Articles

Study of ischemic progression in different intestinal tissue layers during acute intestinal ischemia using swept-source optical coherence tomography angiography.

In acute intestinal ischemia, the progression of ischemia varies across different layers of intestinal tissue. We established a mouse model and used swept-source optical coherence tomography (OCT) to observe the intestinal ischemic process longitudinally in different tissue layers. Employing a method that combines asymmetric gradient filtering with adaptive weighting, we eliminated the vessel trailing phenomenon in OCT angiograms, reducing the confounding effects of superficial vessels on the imaging of deeper vasculature. We quantitatively assessed changes in vascular perfusion density (VPD), vessel length, and vessel average diameter across various intestinal layers. Our results showed a significant reduction in VPD in all layers during ischemia. The mucosa layer experienced the most significant impact, primarily due to disrupted capillary blood flow, followed by the submucosa layer, where vascular constriction or decreased velocity was the primary factor.

Assessment of retinal and choroidal vessel density and nerve fibre layer thickness changes after orbitotomy in patients with severe non-active thyroid orbitopathy: a prospective study.

To evaluate the optical coherence tomography angiogram changes in non-active severe thyroid-related ophthalmopathy patients after cosmetic bone decompression. Eighteen patients (25 eyes) with severe not active not compressive (NANC) TED who were candidates for decompression surgery for cosmetic reasons were included in this study, and a 3 × 3mm macular scan was used to measure vessel density and RNFL thickness. Whole macular vessel density in its superficial, deep and choriocapillaris layers was evaluated. The following data were extracted for each of layers: superior and inferior hemispheres, fovea, parafoveal vessel density, its superior and inferior hemispheres, and temporal, superior, nasal and inferior quadrant. The mean RPC increased postoperatively, which was statistically significant in small vessels of peripapillary area (p-value = 0.045). The mean RNFL thickness decreased after surgery and it was statistically significant in the peripapillary (p-value = 0.032) and Inferior-Hemifield area (p-value = 0.036). The choriocapillaris changes were significant in Superior-Hemifield (p-value = 0.031) and Fovea (p-value = 0.03). Thyroid-associated orbitopathy patients have a tendency to decrease vascular density and correlated with disease activity more than stage of orbitopathy. There was not a strong and even discrepant result in linkage of RNFL thickness and other optic nerve function tests and TED patient status and it is needed to do studies with more epidemiologic power and same methodology of study to be more comparable.

An innovative multi-modal retinal imaging system for in vivo retinal detection in small animals

This paper presents an innovative retinal imaging system tailored for in vivo fundus detection in small animals. This system integrates Scanning Laser Ophthalmoscopy (SLO) and optical Coherence Tomography (OCT) techniques, enabling the simultaneous generation of images from various modalities, including SLO reflectance, SLO fluorescein angiogram, OCT, and OCT angiogram. The existing multi-modal retinal imaging systems generally encounter limitations such as the inability to detect peripheral lesion areas attributed to small Field of View (FOV) design and susceptibility to sample motion due to slow data acquisition speed. To address these challenges, it’s essential to underscore that this proposed system offers a range of notable advantages, including its compact design, the capacity for widefield imaging with a FOV of up to 100°, and a rapid OCT A-scan rate of 250 kHz, notably exceeding the capabilities of pre-existing multi-modal retinal imaging systems. Validation of the system involved imaging the eyes of normal wild-type mice and diseased mice afflicted with retinal detachment and choroidal neovascularization (CNV). The favorable imaging results demonstrate the system’s reliability in identifying retinal lesions in small animals.

Semi-automated algorithm using directional filter for the precise quantification of non-perfusion area on widefield swept-source optical coherence tomography angiograms.

The clinical application of optical coherence tomography angiography (OCTA) has been well documented in literature with its promising potential in dye-less evaluation of various retinal vascular pathologies. Recent advances in OCTA help us gather wider field of view with 12 mm × 12 mm and montage compared to the standard dye-based scans, which has a higher accuracy and sensitivity in detection of peripheral pathologies. The aim of this study is to build a semi-automated algorithm to precisely quantify the non-perfusion areas (NPAs) on widefield swept-source optical coherence tomography angiography (WF SS-OCTA). All subjects underwent imaging on 100 kHz SS-OCTA device acquiring 12 mm × 12 mm angiograms centered on fovea and optic disc. After a comprehensive literature review, a novel algorithm using FIJI (ImageJ) was designed to calculate the NPAs (mm2) after excluding the threshold and segmentation artifact areas from the total field of view. Segmentation and threshold artifacts were first removed from enface structure images using the spatial variance and mean filter respectively. Vessel enhancement was achieved by using 'Subtract Background' followed by directional filter. The cut off for Huang's fuzzy black and white thresholding was defined from the pixel values based of the foveal avascular zone. Then, the NPAs were calculated using the 'Analyze Particles' command with a minimum size of ~0.15 mm2. Finally, the artifact area was subtracted from to give the corrected NPAs. Our cohort had 44 eyes of 30 control patients and 107 eyes of 73 patients with diabetes mellitus (both median age 55 years, P=0.89). Of 107 eyes, 21 eyes had no evidence of diabetic retinopathy (DR), 50 eyes had non-proliferative DR and 36 eyes had proliferative DR. The median NPA was 0.20 (0.07-0.40) in controls, 0.28 (0.12-0.72) in no DR, 5.54 (3.12-9.10) in non-proliferative DR and 13.38 (8.73-26.32) in proliferative DR eyes. Using mixed effects-multiple linear regression analysis adjusting for age, there was significant progressive increase in NPA with increasing DR severity. This is one of the first study to use the directional filter for WFSS-OCTA image processing which is known to be superior to other Hessian based multiscale, linear, and non-linear filters especially for vascular analysis. Our method could greatly refine and streamline the calculation of signal void area proportion, while being much quicker and accurate than manual delineation of NPAs and subsequent estimation. This combined with the wide field of view can have a great prognostic and diagnostic clinical impact for future applications in DR and other ischemic retinal pathologies.

ABNORMALITIES IN THE RETINAL CAPILLARY PLEXUSES IN COATS DISEASE IN ADULTHOOD ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To describe and quantify the abnormalities of the retinal capillary plexuses using optical coherence tomography angiography in Coats disease. Retrospective study. Eleven eyes of 11 patients with Coats disease (9 men and two women aged 32-80 years) compared with nine fellow eyes and 11 healthy control eyes. Horizontal bands of contiguous 3 × 3 mm optical coherence tomography angiograms of the superficial vascular plexus and deep capillary complex were acquired from the optic disk to 6 mm temporal to the fovea, through areas with telangiectasia visible on fluorescein angiography in 9 cases. The vascular density was significantly decreased in both plexuses in eyes with Coats disease compared with normal and fellow eyes within the 6 mm temporal to the fovea (superficial vascular plexus: 21.5 vs. 29.4%, P = 0.00004 and vs. 30.3%, P = 0.00008; deep capillary complex, 16.5 vs. 23.9%, P = 0.00004 and vs. 24.7%, P = 0.00008, respectively). The fractal dimension was also significantly decreased in eyes with Coats disease (superficial vascular plexus: 1.796 vs. 1.848 P = 0.001 and vs. 1.833, P = 0.003; deep capillary complex: 1.762 vs. 1.853, P = 0.003 and vs. 1.838, P = 0.004, respectively). Retinal plexuses' vascular density was decreased in Coats disease, including in areas with no visible telangiectasia.

Topographical Analysis of the Choriocapillaris Reperfusion After Loading Anti-VEGF Therapy in Neovascular AMD.

PurposeThe purpose of this study was to evaluate choriocapillaris vascular density changes around macular neovascularization (MNV) before and after anti-vascular endothelium growth factor (VEGF) injections by optical coherence tomography angiography (OCTA).MethodsTreatment-naïve eyes with a diagnosis of exudative AMD and type 1 MNV were included. En face optical coherence tomography angiograms were analyzed for percentage of choriocapillaris (CC) flow deficit percentage (FD%), the FD average area (FDa), and the FD number (FDn) in 5 progressive 200-µm-wide concentric rings (R1, R2, R3, R4, and R5) surrounding the dark halo around the MNV. The OCTA acquisition was performed at the following visits: (i) before the loading phase of intravitreal injection of aflibercept or ranibizumab (T1), and (ii) 1 month after the last intravitreal injection of loading phase comprising 3 monthly injections (T2).ResultsA total of 30 eyes of 30 Caucasian patients with treatment naïve neurovascular AMD (nAMD) were included in the study. All rings showed a progressive FD% reduction at T2 in comparison to T1 values indicating gradual CC reperfusion of the peripheral rings. Furthermore, we found a progressive contraction of the FD average area in all the rings considered (P < 0.05). On the other hand, at T2, a significant increase in the FD number of the 5 rings was displayed, as compared to T1 (P < 0.05).ConclusionsOur analysis showed topographical CC reperfusion after loading anti-VEGF therapy. CC flow deficits were greater around the associated dark halo before treatment, followed by a progressive recovery of CC flow after intravitreal therapy.Translational RelevanceOCTA may be used to assess the development and progression of MNV but also in assessing response to intravitreal injections of anti-VEGF.

Short-term anatomic response of the choroid to tropicamide in myopic patients.

We aimed to investigate how tropicamide alters subfoveal choroidal thickness (SFChT) and choriocapillaris flow density (CD) and determine the predictive factors of choroid thickness and vascular density in myopic eyes. This retrospective study was conducted from September 2018 to March 2019. SFChT was measured with enhanced depth spectrum-domain optical coherence tomography. The choriocapillaris was imaged using optical coherence tomography angiograms. Ocular parameters were measured thirty minutes before and after 1% tropicamide instillation. Twenty-five eyes of 15 patients (mean age 38.12 ± 6.35 years old and refractive error-8.57 ± 3.37 D) met the study criteria. The baseline linear regression model showed an association of thinner choroid with older age (P = .027) and high myopic patients (P = .001). Tropicamide substantially increased SFChT (P = .001), but had no significant influence on CD (P = .526). Moreover, SFChT variation after tropicamide instillation positively correlated with diopter changes in spherical equivalent (P = .005) and percentage changes in CD (P = .046). In myopic eyes, choroidal layer thickened substantially in response to tropicamide. The increase of SFChT only correlates with variations in spherical equivalent and CD. Short-term tropicamide installation altered both choroid thickness and choroid microvasculature, which implies an interplay among choroidal volume, perfusion, and ciliary muscle tone.

A Case of Choroidal Naevus in a Child

Choroidal naevus is the most common benign intra-ocular tumour. It originates from neural crest derived cells. This lesion is of clinical significance due to risk of visual loss especially if located near the foveola and risk of transformation into malignant melanoma. Traditionally choroidal naevus has been assessed using ultrasound and fluorescein angiography. With advent of new imaging modalities like optical coherence tomography (OCT), fundus autofluorescence (FAF) and OCT angiogram (OCTA) they are being more commonly used to assess naevus. Low risk naevus is defined as one that is unlikely to transform into melanoma. Features of low-risk naevi are thickness

Improvement of retinal OCT angiograms by Sampling Kantorovich algorithm in the assessment of retinal and choroidal perfusion

The aim of this article is to provide an improvement in the reconstruction and visualization of retinal superficial capillary plexus and choriocapillaris images from healthy subjects. The implemented method uses multiple Optical Coherence Tomography (OCT) scanned sequences, performs a registration, an average and a filtering on them using for this last step the Sampling Kantorovich operator (SK). The resulting images are then analyzed with some well known methods in literature to quantitatively evaluate the improvement achieved by the proposed technique. Also fluoroangiography and histological images are introduced as reference to support the reliability and the goodness of the results.

Retinal Vessel Parameters and Choroidal Thickness using Optical Coherence Tomography and OCT Angiogram in Normal Children: A Cross-sectional Study

Introduction: Optical Coherence Tomography (OCT) and OCT Angiogram (OCT-A) are non invasive techniques for imaging the microvasculature of retina and choroid. OCT is a method of analysing the in-vivo retinal architecture. OCT uses low coherence interferometry to create a cross-sectional map of the retina with a resolution of 10-15 µm. Swept Source OCT utilises light source of 1050 nm wavelength and can reproducibly measure choroidal thickness. OCT-A uses the principle of motion contrast, where the moving red blood cells are traced to depict vessels through different segments of the retina. The same tissue area is imaged repeatedly and differences are analysed between scans to detect area with high flow rates, low flow and no flow at all. Only a few studies have been reported on baseline choroidal thickness and retinal vessel parameters in children. This study was conducted to measure these parameters using Swept source OCT in normal children. Aim: To measure retinal vasculature parameters and choroidal thickness using OCT and OCT-A in normal children. Materials and Methods: A cross-sectional study was conducted on 68 children between 5-15 years of age in Department of Ophthalmology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India between February 2018 to July 2018, after obtaining the Ethical clearance from the Institutional review board. The children were divided into two groups, 5-10 years and &gt;10-15 years. Children with Best Corrected Visual Acuity (BCVA) &lt;6/6, axial length&lt; 20/ &gt;25 mm, any systemic disease or ocular pathology were excluded. All underwent comprehensive ophthalmic examination along with fundus photography, OCT and OCTA imaging. Retinal artery and vein calibre at the disc margin and Subfoveal Choroidal Thickness (SFCT) were measured. Measurement of Foveal Avascular Zone (FAZ) both superficial and deep, vascular density (VD) of perifoveal, papillary and peripapillary area were obtained from OCT-A. T-test was used to compare the parameters with p value &lt;0.05 considered as significant. Results: A total of 136 eyes were included. Mean retinal artery measured at superior and inferior disc margin was 176.84±43.88 µm and 177.78±41.69 µm respectively. Mean retinal vein measured at superior and inferior disc margin was 218.90±46.36 µm and 235.37±48.07 µm respectively. Perifoveal images were clear and vessel densities could be anlaysed but papillary and peripapillary vessel densities were not analysed due to poor image quality in many subjects. The mean retinal artery caliber in the age group 5-10 years was 179.85±45.62 µm and 174.00±42.30 µm in the age group &gt;10-15 years at the superior disc margin with p-value of (0.4403). There was no statistical difference retinal vessel caliber between the two groups. The mean SFCT in the 5-10 years group was 344.42±86.77 µm and 343.40± 93.56 µm in the other with a p value 0.9474. The mean superficial FAZ (SFAZ) was189.79±117.11 µm2 in the first group and 264.88±169.91 µm2 in the second group,( p=0.0034). There was no statistical difference among these parameters between the two groups except SFAZ, p=0.0034. Conclusion: Present study describes the normative data on retinal vasculature parameters and choroidal thickness in Indian paediatric population aged 5 to 15 years using OCT and OCT-A. The study findings will further help in screening and monitoring the subjects in this age group.

Comparison of diabetic retinopathy lesions identified using ultrawide field color photography, ultrawide field fluorescein angiography and optical coherence tomography angiography

AbstractPurposeTo determine the correlation of diabetic retinopathy (DR) findings identified on ultrawide field (UWF) color photos, ultrawide field fluorescein angiograms (UWF‐FA) and optical coherence tomography (OCT) angiograms (OCTA).MethodsThis was a cross‐sectional study. Images taken on the same visit were prospectively collected from adult patients with diabetes at a tertiary center in the Philippines. Patients underwent imaging with UWF and UWF‐FA (Optos plc, Dunfermline, Scotland, UK), and OCT with OCTA (Carl Zeiss Meditec Inc, Dublin, CA, USA). Images were evaluated for the presence of DR lesions and center‐involving diabetic macular edema (ciDME). Ischemia was identified on UWF‐FA using Image J Fiji software (National Institutes of Health, Bethesda, MD, USA) and nonperfusion index (NPI) was determined using previously validated protocols. Automated measurements of the macular vessel density (VD), vessel perfusion (VP) and foveal avascular zone (FAZ) metrics were obtained on OCTA.ResultsImages from 69 eyes were included in the analysis. Increasing DR severity was associated with higher NPI (r = 0.55944, p &lt; 0.001) and remained significant after distinguishing between cones (Cone Nonperfusion Index [CPI]: r = 0.55617, p &lt; 0.0001) and rods (Rod Nonperfusion Index [RPI]: r = 0.55285, p &lt; 0.0001). In eyes with NPDR, higher NPI is correlated with the presence of ciDME (r = 0.51156, p 0.0017). Furthermore, macular nonperfusion on UWF‐FA was correlated with higher NPI (r = 0.42899, p 0.0101), CPI (r = 0.50028, p 0.0022) and RPI (r = 0.49027, p 0.0028). Central VD and VP were correlated with the presence of ciDME (r = 0.52456, p &lt; 0.0001; r = 0.51952, p &lt; 0.0001) on OCT. A larger FAZ area was correlated with decreased central VD (r = −0.60089, p 0.0001) and decreased central VP (r = −0.59224, p 0.0001).ConclusionsThe collective findings of UWF, UWF‐FA and OCTA provide complementary information on diabetic eyes, and may offer insights on the pathogenesis and progression of DR.

Association Between Fluid Volume in Inner Nuclear Layer and Visual Acuity in Diabetic Macular Edema

In diabetic macular edema (DME), the correlation between visual acuity (VA) and central subfield thickness (CST) is weak. We hypothesize that fluid volume (FV) in the inner nuclear layer (INL) may correlate more strongly with VA. Retrospective, cross-sectional study. One eye each of diabetic patients with DME was included. We measured intraretinal fluid volume that was detected by automated fluid detection algorithm on 3-×3-mm optical coherence tomography angiogram volume scans. The detected fluid was subdivided into inner FV, bounded by the INL, and outer FV, the fluid between the outer border of INL to the ellipsoid zone. We enrolled 125 patients with DME (60 women; mean age, 61 years). The mean detected inner FV was 0.013 mm3 in 109 eyes (87%). The mean detected outer FV was 0.042 mm3 in 124 eyes (99%). Univariate analysis demonstrated that the VA significantly correlated with the inner FV (P < .0001), whole macular FV (P=.010), and CST (P=.036). Multivariate analysis demonstrated that the inner FV was the only significant factor (β=-0.41, P=.004). These correlations were consistent when the treatment-naïve group (n=33) and the eyes without previous laser treatments (n=93) were analyzed separately. The area under the receiver operating characteristic curve of inner FV for VA of 20/32 or worse was significantly higher than that for CST (0.66 vs 0.54, P=.018). The inner FV has a stronger association with VA than other OCT biomarkers in DME and may be more clinically useful.

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

SynopsisA 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...

Automated detection of glaucoma using elongated quinary patterns technique with optical coherence tomography angiogram images

Glaucoma is the second most common cause of blindness worldwide after cataracts. It presents a great health concern as it is usually undetectable during the early stages without regular screening. Noticeable symptoms of glaucoma may only appear at a later stage. The eye disease progresses over time without treatment. Clinicians are specially trained to identify and diagnose glaucoma. However, reasons such as fatigue and observer errors may impair the clinician’s judgement. Hence, a trained computer-aided diagnosis system is necessary to prevent such issues. Optical coherence tomography angiography (OCTA) images were used to detect glaucoma. In this work, we have used elongated quinary patterns (EQP) technique to obtain multi-gradient magnitudes and angles. Various texture features are extracted from the various levels of gradients and angles of EQP images. Optimal features selected using Student’s t-test are fed to an ensemble classifier and 10-fold cross validation strategy is employed in which adaptive synthetic (ADASYN) is applied to reduce the bias. In this work, we have obtained an accuracy of 95.1% for the detection of left eye (OS) disc centered OCTA images. This developed system is available for further evaluation using more images.

Optical Coherence Tomography Angiography Monitors Cutaneous Wound Healing under Angiogenesis-Promoting Treatment in Diabetic and Non-Diabetic Mice

During wound healing, the rapid re-establishment of a functional microcirculation in the wounded tissue is of utmost importance. We applied optical coherence tomography (OCT) angiography to evaluate vascular remodeling in an excisional wound model in the pinnae of C57BL/6 and db/db mice receiving different proangiogenic topical treatments. Analysis of the high-resolution OCT angiograms, including the four quantitative parameters vessel density, vessel length, number of bifurcations, and vessel tortuosity, revealed changes of the microvasculature and allowed identification of the overlapping wound healing phases hemostasis, inflammation, proliferation, and remodeling. Angiograms acquired in the inflammatory phase in the first days showed a dilation of vessels and recruitment of pre-existing capillaries. In the proliferative phase, angiogenesis with the sprouting of new capillaries into the wound tissue led to an increase of the OCT angiography parameters vessel density, normalized vessel length, number of bifurcations, and vessel tortuosity by 28–47%, 39–52%, 33–48%, and 3–8% versus baseline, respectively. After the peak observed on study days four to seven, the parameters slowly decreased but remained still elevated 18 days after wounding, indicating a continuing remodeling phase. Our study suggests that OCT angiography has the potential to serve as a valuable preclinical research tool in studies investigating impaired vascular remodeling during wound healing and potential new treatment strategies.

Deep learning differentiates between healthy and diabetic mouse ears from optical coherence tomography angiography images.

We trained a deep learning algorithm to use skin optical coherence tomography (OCT) angiograms to differentiate between healthy and type 2 diabetic mice. OCT angiograms were acquired with a custom‐built OCT system based on an akinetic swept laser at 1322 nm with a lateral resolution of ∼13 μm and using split‐spectrum amplitude decorrelation. Our data set consisted of 24 stitched angiograms of the full ear, with a size of approximately 8.2 × 8.2 mm, evenly distributed between healthy and diabetic mice. The deep learning classification algorithm uses the ResNet v2 convolutional neural network architecture and was trained on small patches extracted from the full ear angiograms. For individual patches, we obtained a cross‐validated accuracy of 0.925 and an area under the receiver operating characteristic curve (ROC AUC) of 0.974. Averaging over multiple patches extracted from each ear resulted in the correct classification of all 24 ears.

Long-term capillary changes in areas of dissociated optic nerve fibre layer after macular hole surgery.

Internal limiting membrane (ILM) peeling for macular hole (MH) surgery may cause retinal abnormalities, visible on blue-filter fundus photographs as arcuate, slightly dark, extramacular striae along the course of retinal nerve fibres. This feature, showing a dissociated optic nerve fibre layer (DONFL) appearance, perfectly corresponds to focal dehiscences (‘dimplings’) in the retinal nerve fibre layer (RNFL) on B-scan optical coherence tomography (OCT) and to concentric macular dark spots on en-face scan OCT. Although such retinal changes seem not to preclude a good visual outcome, their origin is still unclear (Tadayoni et al. 2001). We report herein the long-term capillary changes occurring in DONFL areas in 38 MH patients (16 men, 22 women) treated with ILM peeling technique. All subjects underwent extensive ophthalmic examination and retinal imaging, including structural OCT, OCT angiography and colour-coded perfusion maps, before and after surgery. En-face OCT angiograms of the superficial capillary plexus (SCP) were evaluated and compared with structural OCT findings. All angiograms and OCT images were exported into a validated custom measurement software (ImageJ software version 1.50, National Institutes of Health, Bethesda, MD). En-face scan OCT of SCP slabs was binarized by Otsu’s method. DONFL location was automatically delineated, and DONFL edges were semi-automatically overlapped on the corresponding colour-coded perfusion maps. Finally, vascular perfusion density (VPD) values of each retinal sector were correlated with the corresponding DONFL area. All eyes were followed-up postoperatively for a mean of 25.2 ± 3.2 months (range 24–29 months). Anatomical MH closure was achieved in 37/38 (97.4%) eyes. At the last follow-up examination, 34/38 (89.5%) eyes had DONFL areas, mainly in the temporal macula. Overlapping of delineated DONFL areas with colour-coded perfusion maps showed a perfect correspondence between temporal DONFL areas and no-flow regions in the temporal SCP, whereas no such correspondence was found in other SCP sectors (Table 1). Macular changes following ILM peeling are still poorly understood. Muller cell (MC) footplates are in direct contact with RNFL bundles and contribute to ILM formation. The mechanical trauma secondary to ILM peeling is likely to cause an injury to these structures, resulting in axon swelling and gaps in the RNFL, which appear as DONFL areas. Furthermore, petechial haemorrhages, often occurring on the retinal surface during ILM peeling, could be the result of direct injury to SCP vessels. DONFL areas usually appear 1–3 months after surgery in the temporal macula, where MC footplates are more numerous, progressively increase in the following 3–6 months and completely surround the fovea within 12 months (Alkabes et al. 2011; Navajas et al. 2020). Thereafter, progressive regeneration of MC footplates and DONFL attenuation may occur (Nakamura et al. 2003; Kishimoto et al. 2011). In our study, DONFL areas were still detectable in the temporal sectors after two years, thus suggesting that macular restoration may have started nasally. Furthermore, we found a statistically significant correlation between the total area of DONFL and VPD values only in the temporal SCP. Overall, these findings support the idea that retinal reparation begins with SCP regeneration and is later followed by MC footplates restoration, with final attenuation and disappearance of DONFL. Accordingly, we hypothesize three steps in the process of retinal reparation after MH surgery: (1) development of roundish no-flow regions on colour-coded perfusion maps and DONFL areas on en-face scan OCT in the temporal SCP, where both vessels and MC have been damaged; (2) persistence of DONFL areas corresponding to normal perfusion regions (superior-middle, superior-nasal, inferior-middle and inferior-nasal sectors of the SCP), because vessel restoration has been completed, but MC is still damaged; and (3) injury to SCP vessels and MC has been completely restored and neither DONFL areas nor no-flow regions can be found (intermediate-nasal sector). Further larger prospective studies are warranted to confirm this theory and fully understand the pathogenesis underlying macular changes secondary to ILM peeling in MH patients.

Choriocapillaris Flow Deficits and Treatment-Naïve Macular Neovascularization Secondary to Age-Related Macular Degeneration.

PurposeTo evaluate choriocapillaris (CC) flow deficits (FD) in eyes with treatment-naïve macular neovascularization (MNV) and to compare CC FD around exudative versus nonexudative MNV.MethodsTreatment-naïve eyes with a diagnosis of either exudative or nonexudative AMD and type 1 MNV were included. Normal control eyes were age-matched to each AMD eye one to one. En face optical coherence tomography angiograms were analyzed for percentage of CC FD (FD%) in two concentric 500 µm rings, ring 1 and ring 2, surrounding the dark halo around MNV. The mean CC FD% in ring 1 and ring 2 was evaluated for each eye. A secondary analysis was similarly carried out to investigate the differences in CC FD% in exudative versus nonexudative treatment-naïve MNV.ResultsTwenty-three eyes with treatment-naïve MNV were age matched with 23 normal controls. The mean CC FD% was significantly greater in both rings in the MNV versus the normal control group (P < 0.05) and was significantly greater in the inner ring, closer to the lesion, than the outer ring. The mean FD% was also greater in both rings in the exudative versus the nonexudative MNV group, but this difference did not reach statistical significance.ConclusionsThe CC FD% was greater in the area surrounding MNV versus age-matched normal controls and in the ring closer to the MNV lesion. Further, CC FD was greater in eyes with exudative versus nonexudative MNV in both rings surrounding the associated dark halo, although this difference was not statistically significant.

Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain-Optical Coherence Tomography Angiography.

To assess longitudinal microvascular changes in eyes treated with I-125 episcleral plaque brachytherapy (EPB). High resolution OCT angiograms of the central 3×3mm macula were obtained from I-125 episcleral plaque brachytherapy treated and untreated fellow eyes of 61 patients. Capillary density (vessel skeleton density, VSD) and caliber (vessel diameter index, VDI) were quantified using previously validated semi-automated algorithms. Nonperfusion was also quantified as flow impairment regions (FIR). Exams from treated and fellow eyes obtained pre-treatment and at 6-month, 1-year, and 2-year intervals were compared using generalized estimating equation linear models. Dosimetry maps were used to evaluate spatial correlation between radiation dose and microvascular metrics. At 6 months, treated eyes had significantly lower VSD (0.145 ± 0.003 vs 0.155 ± 0.002; p = 0.009) and higher FIR (2.01 ± 0.199 vs 1.46 ± 0.104; p = 0.010) compared to fellow eyes. There was a significant decrease in VSD and a corresponding increase in FIR even for treated eyes without clinically identifiable retinopathy at 6 months. VDI was significantly higher in treated eyes than in fellow eyes at 2 years (2.92 ± 0.025 vs 2.84 ± 0.018; p < 0.001). When our cohort was categorized into low dose radiation (<15Gy) and high dose radiation (>45Gy) to the fovea, there were significant differences in VSD and FIR between groups. OCTA can be used to quantify and monitor EPB induced retinopathy, and can detect vascular abnormalities even in the absence of clinically observable retinopathy. OCTA may therefore be useful in investigating treatment interventions that aim to delay EPB-induced radiation retinopathy.

PREDICTIVE ACTIVATION BIOMARKERS OF TREATMENT-NAIVE ASYMPTOMATIC CHOROIDAL NEOVASCULARIZATION IN AGE-RELATED MACULAR DEGENERATION.

To assess the long-term evolution of treatment-naive quiescent choroidal neovascularization (CNV), in age-related macular degeneration (AMD), to identify predictive activation biomarkers. Patients with quiescent CNV underwent a comprehensive ophthalmological examination, including fluorescein and indocyanine green angiographies, structural optical coherence tomography (OCT), and OCT angiography. Qualitative and quantitative analyses of structural OCT and OCT angiography images were performed during the study period. At the last follow-up evaluation, the enrolled eyes were divided into two groups: eyes with quiescent CNV converting to exudative AMD (eAMD) and those not progressing to eAMD. Sixty-eight eyes of 68 patients were enrolled in the study. Mean follow-up duration was 40 ± 28 months using multimodal imaging and 22 ± 13 months using OCT angiography. On structural OCT, quiescent CNV not converting to eAMD showed a preferential growth of the pigment epithelium detachment greatest linear diameter (P = 0.009), whereas the eAMD group presented a preferential growth of the pigment epithelium detachment maximal height (P < 0.0001) during the study period. Quantitative analysis of choriocapillaris OCT angiograms confirmed the CNV area growth during follow-up (from 4.18 ± 4.77 mm at baseline to 5.10 ± 5.06 mm at the last follow-up visit; P = 0.02). A close follow-up is recommended to early identify predictive activation biomarkers of treatment-naive quiescent CNV.