Superficial Capillary Network Research Articles

Vascular changes in the retinal capillary network in fellow eye of the patients with central retinal artery occlusion.

We aimed to evaluate the retinal vascular changes in the superficial and deep retinal vascular networks in the fellow eye of patients with central retinal artery occlusion (CRAO) and compare them with controls using optical coherence tomography angiography (OCT-A). In a cross-sectional study, 27 patients with CRAO and 189 normal controls were included. Ophthalmic examination and OCT-A images were performed on all participants. The total vascular density of the superficial capillary network in the 6-mm scan was significantly lower in the fellow eye of patients with CRAO than in the control group (p = 0.02). No significant difference was observed in the FAZ area of the affected eyes and their fellow eyes compared with the controls. Total vascular density at 300 microns around the fovea was lower in the fellow eye compared with the control group (p = 0.034). The retinal vascular network changes in the fellow eyes of patients with CRAO suggest that persistent microvascular changes may be present before the onset of CRAO. This finding indicates that such changes could serve as an early diagnostic window for systemic vascular changes before catastrophic vascular events occur.

Choroidal thickness and retinal vascular changes in patients with lichen planus: an inflammatory disease beyond the skin.

Lichen planus (LP) is a common inflammatory condition of unknown etiology that commonly affects the skin and mucous membranes. Optical coherence tomography angiography (OCTA) is a noninvasive technique for identifying early retinal vascular impairment in systemic disease without clinical damage by imaging deep and superficial capillary networks. To assess the impacts of LP on the choroid and assess vascular changes in retinal capillary density using OCTA. This single-center prospective case-control study included 30 therapeutic-naïve LP patients and 30 age and sex-matched healthy individuals. All study subjects underwent a complete ophthalmological examination, including best-corrected visual acuity (BCVA) measurement using a Snellen chart, slit-lamp biomicroscopy, intraocular pressure (IOP) measurement, and fundus examination. They were then examined using spectral domain OCT and choroidal thickness was measured. The vessel density of the superficial and deep capillary networks was measured and assessed using OCTA. Patients had significantly thicker choroidal and retinal thickness than controls, with subfoveal, nasal, and temporal areas showing a significant difference. A significantly higher vascular density in the superficial capillary plexus, particularly in the nasal perifoveal area, was found compared to the control group. Significantly, higher vascular density in the deep capillary plexus in the parafoveal area compared to controls was reported. Significant correlations were found between visual acuity and IOP, and age, duration of disease, and severity of disease. This study is the first to reveal that LP patients exhibit choroidal changes and retinal vascular alterations compared to healthy controls.

Optical coherence tomography angiography: a review of the current literature

This narrative review presents a comprehensive examination of optical coherence tomography angiography (OCTA), a non-invasive retinal vascular imaging technology, as reported in the existing literature. Building on the coherence tomography principles of standard OCT, OCTA further delineates the retinal vascular system, thus offering an advanced alternative to conventional dye-based imaging. OCTA provides high-resolution visualisation of both the superficial and deep capillary networks, an achievement previously unattainable. However, image quality may be compromised by factors such as motion artefacts or media opacities, potentially limiting the utility of OCTA in certain patient cohorts. Despite these limitations, OCTA has various potential clinical applications in managing retinal and choroidal vascular diseases. Still, given its considerable cost implications relative to current modalities, further research is warranted to justify its broader application in clinical practice.

Quantitative Measurements of Macular and Optic Nerve Head Blood Flow Parameters Following Cataract Surgery in Eye Department, Red Cross Tertiary General Hospital, Athens, Greece

Objective: To evaluate the effect of uncomplicated cataract surgery on macular and optic nerve head blood flow with Optical Coherence Tomography Angiography (OCT-A). Retinal vascular changes and macular vessel remodeling following cataract surgery is an area of interest, as the effect, cause and duration of such changes remain debatable.
 Setting: Eye Department, Red Cross Tertiary General Hospital, Athens, Greece.
 Methods: In this study, we recruited cataract surgery candidates who had regular post operative visits and underwent longitudinal OCT-A examinations before and after surgery.
 Results: Macular vessel density increased in the post operative visits both in the superficial (SCP) and deep capillary network (DCP) (P<0.001) and showed a persistent effect over 3 months follow-up. Macular thickness increased over the first postoperative month, but returned to preoperative values at 3 months. Foveal avascular zone (FAZ) measurements and vessel density at radial peripapillary capillaries (RPC) were unaffected.
 Conclusions: OCT-A enables a quantitative analysis of blood flow by regular patient monitoring. In this study, we found that after cataract surgery, macular blood flow increased significantly. The reason for this could be attributed to post operative inflammatory process or vascular remodeling due to change in retinal metabolic demands.

Post COVID-19 Retinal Evaluation Using Optical Coherence Tomography Angiography: A Case Control Study

ABSTRACT Purpose To study the effect of coronavirus disease of 2019 (COVID-19) on retinal vasculature by Optical Coherence Tomography Angiography (OCTA). Methods Macular OCTA images of patients recovered from COVID-19 infections were studied including foveal avascular zone (FAZ), capillary vascular densities (CVD) of the superficial and deep capillary network (SCP, DCP), and central foveal thickness (CFT). Results The FAZ area was significantly larger in post COVID-19 cases compared to the healthy controls (p=0.032). Post COVID-19 cases had significant lower CVDs in perifoveal quadrants of the SCP. They also had lower CVD in the whole area, parafoveal, temporal and inferior perifoveal areas in the DCP. The parafoveal DCP area showed a positive correlation with disease duration (r=0.249, p-value=0.018). The whole SCP was significantly larger in cases with lymphopenia (p-value=0.004). Conclusion This study found asymptomatic retinal vascular affection in post COVID-19 eyes showing a relation with disease clinical and laboratory features.

Optical coherence tomography angiography biomarkers of microvascular alterations in RVCL-S.

BackgroundThe brain and retina share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in patients with a monogenic vasculopathy using optical coherence tomography angiography (OCTA). OCT-A is a novel precise non-invasive imaging method that may provide biomarkers suitable for diagnosis and follow-up of small vessel diseases.MethodsIn this exploratory cross-sectional study, eleven RVCL-S patients and eleven age-matched healthy control participants were included. The size of the foveal avascular zone (FAZ) and the vascular density of the superficial capillary networks in the retina were measured by OCT-A.ResultsThe symptomatic and presymptomatic patients showed significantly lower vascular density values than controls in the foveal region [median (IQR) 18.2% (15.8–18.6) vs. 24.4% (21.5–26.8) (p < 0.001), 29.8% (29.6–30.8) vs. 33.2% (32.0–33.6) (p = 0.002), respectively]. The FAZ was significantly larger in the symptomatic RVCL-S patients than in the control group [13,416 square pixels [7,529–22,860] vs. 1,405 square pixels [1,344–2,470] (p < 0.001)]. No significant difference was identified in measurements of FAZ comparing presymptomatic and controls.ConclusionOur findings with OCT-A demonstrated that RVCL-S causes an increase in the size of the FAZ in symptomatic RVCL-S patients compared to healthy participants. Moreover, there is a decrease in vessel density in the superficial capillary networks in both symptomatic and presymptomatic patients. In the future, newly developed precise objective instruments such as OCT (-A) may provide important tools in determining disease activity for follow up of common small vessel diseases.

Optical coherence tomography angiography metrics predict normal tension glaucoma progression.

ABSTRACTPurposeTo prospectively determine the relationship between optical coherence tomography angiography (OCTA) metrics and visual field (VF) progression in eyes with normal tension glaucoma (NTG).MethodsProspective, cohort study conducted from January 2017 to October 2021. OCTA metrics at the peripapillary region (circumpapillary vessel density (cpVD), vessel diameter index (VDI) and fractal dimension (FD) in the radial superficial capillary network), and the macular region (macular vessel density, foveal avascular zone (FAZ) area, FAZ circularity and macular FD in superficial capillary plexus (SCP) and deep capillary plexus (DCP)), were investigated and measured by a customized MATLAB program. VF was evaluated semiannually using standard automated perimetry. Cox proportional hazards model was used to evaluate the relationship of OCTA metrics at baseline to the risk of NTG progression over time.ResultsThe cohort included 164 NTG patients (270 eyes), which were followed up for at least 2 years. Over a mean follow‐up period of 48.58 ± 7.98 months, 42 of the 270 NTG eyes (15.56%) developed VF deterioration. Among OCTA metrics at peripapillary region, lower superotemporal cpVD (HR per SD decrease, 1.401; 95% CI, 1.017–1.929) was associated with VF deterioration after adjusting for reported risk factors at baseline.ConclusionsLower superotemporal cpVD at peripapillary region measured from OCTA improves the prediction of VF deterioration in NTG. These findings provided further evidence to support the prognostic role of OCTA in the risk assessment of NTG progression.

Features of interpretation of data of light and spectral dermatoscopy in patients with actinic keratosis

Actinic keratosis (AK) is a common disease that is formed as a result of excessive insolation of exposed skin areas. One of the possible options for the development of the disease is the transformation of AK into squamous cell carcinoma. The timely diagnosis of suspicious areas of AK with their subsequent excision and histological examination has great importance in the prevention of neoplastic transformations of the skin.The aim of our study was to identify dermatoscopic patterns of the initial stages of neoplastic transformation of actinic keratosis and a comparative analysis of the diagnostic effectiveness of digital dermatoscopy, two­color spectral dermatoscopy in relation to histological examination in a group of individuals suffering from actinic keratosis.There were 49 patients with AK under our supervision. All suspected cases of keratosis were additionally examined histologically. We analyzed the features of clinical forms and modified existing diagnostic methods. To expand the diagnostic capabilities of standard dermatoscopy, studies were performed in different ranges of light. Spectral dermatoscopy allowed estimating the potential foci of neoplastic transformation in blue and green light field (standard illumination range was suppressed). Particular attention was paid to areas of increased keratinization, areas of excessive vascularization with a predominance of superficial capillary network, micro­ulcers with loose edges that contrast well with the green spectrum, as well as dynamic changes in color in one field of study for 30 days.It was found that the use of spectral dermatoscopy increases the diagnostic capabilities of AK and allows identifying more accurately the early signs of neoplastic transformations associated with both pathological neoangiogenesis («strawberry» pattern, glomerular network) and pathological proliferation (pseudogranulations, pathological keratinization, etc.).

MORPHOLOGY OF TONGUE VASCULAR BED CURRENT OF RATS IN HEALTH

At present it is known that the morphology of the tongue mucous membrane is significantly impacted by the state of the internal organs that is manifested indirectly through the nervous and circulatory systems. This necessitates a detailed study of the structure of the tongue vascular system. The aim of this study was to investigate the morphology of tongue vascular bed in intact white rats. The study was performed on 10 outbred white rats of both sexes, weighing 204±0.67 g. The experiment was conducted in accordance with the bioethical norms and ethical principles of work with experimental animals. Traditional paraffin and semi-thin sections were made from the preparations of the tongue and then examined with a light microscope. We have found the tongue vascular bed in white rats by its general characteristics is very similar to the vascular bed morphology of human tongue. We distinguish two relatively autonomous associations of blood micro vessels in the tongue circulatory bed of white rats. The first is represented by a capillary network running through the muscles of the tongue and providing trophism of the muscles and small salivary glands of the tongue. The second is localized in the lamina propria of the mucous membrane and, in turn, is divided into a superficial capillary network in the connective tissue papillae, the main purpose of which is indirect provision of trophic processes of multilayered squamous keratin epithelium, and deep capillary network providing blood supply to the connective tissue. The microcirculatory bed of the tongue mucous membrane in white rats has noticeable differences in metric parameters in the area of the apex, body and basal parts, which must be taken into account when interpreting experimental studies.

Use of ultra-wide field retinal imaging and optical coherence tomography angiography in the diagnosis of incomplete Susac syndrome.

To describe clinical findings through ultra-wide field (UWF) images and optical coherence tomography angiography (OCT-A), in Susac's syndrome (SS). SS patients were retrospectively analyzed in a single center. Clinical features, ultra-wide-field retinographies (UWF-PR), UWF fluorescein angiographies (UWF-FA), and optical coherence tomography angiography & en face (OCT-A/EF) were reviewed. Twelve eyes from six patients with a mean follow-up of 35.66 months ± SD 36.88 were included. UWF-PR showed areas of retinal whitening and cotton-wool spots in all the eyes after acute attack. Segmentary mid peripheral arteriolitis could be observed in five eyes by UWF-FA in acute and convalescent stages. OCT-A revealed capillary density changes in all of the affected eyes. During the acute phase there was a well-preserved superficial capillary network, while deep retinal plexus showed a lower density in the affected areas. OCT-A/EF revealed deep retinal plexus drop-out and surrounding edematous retina in acute attacks, becoming atrophic over time. Conversely, superficial plexus was much less affected. Perifoveal reperfusion was seen in seven eyes after the acute attack. UWF-PR/FA and OCT-A/EF might be helpful to stablish an early diagnosis and to monitor SS progression.

The peripapillary retinal capillary density is highly correlated with its nerve fibre layer in normal population.

To explore the peripapillary capillary density distribution and its correlation with nerve fibre layer in superficial and deep retinal layers of healthy Chinese. Images of superficial and deep retinal capillary networks were obtained by optical coherence tomography angiography (OCTA) using a CIRRUS TM HD-OCT Model 5000 system and analyzed by Image-Pro Plus (Medical Cybernetics, Version 6.0). Peripapillary capillary density was defined as the mean optical density of the annular region between two concentric circles of 3.085 mm and 3.835 mm diameter. Parafoveal capillary density was defined as the mean optical density between the foveal avascular zone (FAZ) boarder and a 2.5 mm diameter circle. Retinal nerve fibre layer (RNFL) thickness was also measured and the correlation with capillary density determined. Mean peripapillary capillary density was 4.16±1.06 in the superficial and 2.92±0.80 in the deep layer. Corresponding mean parafoveal densities were 2.65±0.55 and 2.51±0.55. Capillary densities were higher in the superficial layer of all quadrants for both peripapillary and parafoveal regions (P < 0.001). A significant correlation between peripapillary capillary density and RNFL thickness was found in the superficial layer (r = 0.305, P < 0.05). A negative correlation between age and capillary density was found in both peripapillary and parafoveal regions (P < 0.001). Peripapillary capillary density in the superficial layer highly correlated with RNFL thickness. Regional and age-related differences in peripapillary and parafoveal capillary density should be considered when diagnosing and monitoring individuals with diseases affecting retinal capillary density.

Optical Coherence Tomography Angiography Contributions in Classification of Nonproliferative Diabetic Retinopathy.

Introduction:To show the importance of optical coherence tomography (OCT) angiography imaging of superficial and deep capillary network in patients with non-proliferative diabetic retinopathy (NPDR), and to show the correlation between blood glucose level and changes in the foveal microvasculature.Methods:A cross-sectional study was performed on eyes with NPDR and healthy subjects using a highspeed 840-nm-wavelength spectral-domain optical coherence tomography instrument (RTVue XR Avanti; Optovue, Inc, Fremont, California, USA). Blood flow was detected using the split-spectrum amplitude-decorrelation angiography algorithm. A fully automated microstructural analysis of the foveal avascular zone (FAZ) and avascular surfaces was performed. Quantitative values from diabetic patients were compared with those of healthy subjects. Data about blood status in diabetic patients and healthy subjects were taken from patients’ medical history.Results:Size of both, FAZ and vascular dropout are significantly different between healthy patients and patients with NPDR. OCT angiography detected enlargement and distortion of the foveal avascular zone, retinal capillary dropout, and a higher number of vascular loops and microaneurysms. Sizes of FAZ and vascular dropout increase with the duration of disease. Central macular thickness (CMT) is not significantly different between healthy patients and patients with NPDR. A study has proven a positive correlation between the size of FAZ and the size of vascular dropout in superficial vascular plexus in patients that have DM over 10 years.Conclusion:A qualitative and quantitative OCT angiography approach to retinal vascular status can offer objective data on monitoring patients with non-proliferative diabetic retinopathy as well as indicate the progression of the disease.

Retinal and Choroidal Perfusion Status in the Area of Laser Scars Assessed With Swept-Source Optical Coherence Tomography Angiography.

To evaluate the perfusion status of the retina and choriocapillaris in the area of laser scars on swept-source optical coherence tomography angiography (OCTA) images of eyes previously treated with panretinal photocoagulation (PRP). Cross-sectional exploratory analysis of swept-source OCTA images, which were retrospectively reviewed for laser scars. The appearance of the capillary networks in the area of previous laser were evaluated following a three-step grading system (normal/sparse/missing capillary network). The superficial and deep capillary plexus of the retina and the choriocapillaris were graded separately. A total of 3140 laser scars in 54 eyes of 31 patients (13 female, mean age 57 ± 12 years) were included in this analysis. In the retina, 6.8% of the superficial and deep capillary network in the area evaluated appeared normal, 58% and 56% sparse, and 35% and 37% missing. Capillary dropout in the retina was not restricted to the area of prior laser treatment. The choriocapillaris decorrelation signal was either sparse (61%) or completely missing (38%) within the laser scar area. The perfusion of the choriocapillaris appeared normal in the area adjacent to laser scars. Capillary non-perfusion in the choriocapillaris was found within the laser scar area. Laser treatment seems to cause sustained non-perfusion of choriocapillaris in the area treated.

Comparison of vascular parameters between normal cynomolgus macaques and healthy humans by optical coherence tomography angiography

BackgroundThe metabolic activity of retina is higher than other human tissues and is crucial to the vision. Cynomolgus macaques is widely used in ophthalmic disease research. The evaluation and comparison of macular and optic disc vascular circulation parameters between normal adult cynomolgus macaques and healthy adult humans using OCT-A can promote better use of nonhuman primate models in studies of ophthalmic vascular disease.MethodsTwelve normal adult cynomolgus macaques with a mean age of 4.91 ± 0.43 years were studied for data collection. The macula of 28 adult healthy humans (14 males and 14 females), with a mean age of 25.11 ± 6.21 years and the optic discs of 9 adult healthy humans (4 males and 5 females) with a mean age of 28.56 ± 6.78 years were measured. The vessel density (VD) was measured using an RTVue XR with AngioVue. The scan sizes of the macular and optic discs were 3 × 3 mm and 4.5 × 4.5 mm, respectively.ResultsOCT-A can image the superficial and deep capillary plexuses and radial peripapillary capillary network. In RPC layer of the optic disc, the VD in the nasal quadrant was lower than the VD in the inferior temporal quadrant. Similarities and significant differences in VD between healthy humans and cynomolgus macaques were obtained using OCT-A.ConclusionsThis study provides normal vascular parameters for adult cynomolgus macaques using OCT-A to help establish an optical parameter database for cynomolgus macaques and compare VD between healthy humans and cynomolgus macaques to promote choroid-retinopathy research.Trial registrationCurrent Controlled Trials NCT03692169, retrospectively registered on 26 sept 2018.

Macular retinal thickness and flow density change by optical coherence tomography angiography after posterior scleral reinforcement

Optical coherence tomography angiography (Angio-OCT) has introduced a new non-invasive, quantitative method to assess superficial and deep capillary networks of the retina. In this study, we investigated macular retinal thickness and flow density change following posterior scleral reinforcement (PSR) surgery, using an RTVue XR Avanti Angio-OCT (A2016.2.0.35, Optovue, Fremont, CA), in patients with pathological myopia. A total of 13 patients with pathological myopia were recruited and all patients completed the 6 months follow-up visit. Data from 22 eyes were used in this study. The mean age was 36.23±15.29 years, and 43% (n=6) were men. Spherical equivalent refractive error (SE) ranged from -8.0 to -24.0 D. Post-operative axial length, best-corrected visual acuity and SE did not change significantly at each follow-up, compared with preoperative measure (all P>0.05). Postoperative flow density of superficial and deep retinal layers at each sector did not change significantly at each follow-up, compared to pre-operative measure (all P>0.05). However, we found significant decrease in retinal thickness of parafovea-inferior sector after PSR surgery (P<0.01), indicating potential relaxation of vitreofoveal traction after PSR surgery.

Evaluation of Foveal Avascular Zone and Capillary Plexuses in Diabetic Patients by Optical Coherence Tomography Angiography.

PurposeTo investigate the foveal avascular zone (AVZ), superficial and deep foveal and parafoveal vessel density (VD) changes related to diabetic retinopathy.MethodsForty-nine type 2 diabetes mellitus (DM) and 45 healthy control subjects were included in this study. The demographic data (age and sex), disease duration, and level of glycated hemoglobin were collected. Superficial VD (%), superficial AVZ area (mm2), deep VD (%) and deep AVZ area (mm2) were evaluated via optic coherence tomography angiography.ResultsSuperficial AVZ was 0.438 ± 0.05 mm2 in the DM group, 0.246 ± 0.022 mm2 in the control group (p < 0.001). Deep AVZ was 0.732 ± 0.06 mm2 in the DM group, and 0.342 ± 0.022 mm2 in the control group (p < 0.001). Superficial foveal VD was 29.45 ± 0.76 mm2 in the DM group, and 34.86 ± 0.75 mm2 in the control group (p < 0.001). Deep foveal VD was 24.85 ± 1.08 mm2 in the DM group, and 33.47 ± 0.56 mm2 in the control group (p < 0.001).ConclusionsIn this study, we demonstrated an enlargement in the foveal AVZ along with a reduction in the vascular density of the superficial and deep capillary network in the foveal and parafoveal area using optic coherence tomography angiography in patients with nonproliferative diabetic retinopathy. This technique can be used to monitor the progression of the disease and to evaluate the response to treatment.

Swept-source optical coherence tomography and optical coherence tomography angiography in acquired toxoplasmic chorioretinitis: a case report

PurposeTo describe swept-source optical coherence tomography and optical coherence tomography angiography retinal changes in a case of acute toxoplasmic chorioretinitis both at the time of diagnosis and after healing.Case presentationA 57-year-old white woman suffering from acquired toxoplasmic chorioretinitis underwent swept-source optical coherence tomography and optical coherence tomography angiography both at the time of diagnosis and after healing. In the acute phase of the disease, swept-source optical coherence tomography clearly showed retinal and choroidal involvement in the superficial retina and in the choroidal swelling. Optical coherence tomography angiography showed a complete loss of deep and superficial capillary networks and of choroidal vessels in the area of the inflammation. After healing, swept-source optical coherence tomography showed a retinal thinning of the area involved, with a subversion of retinal layers and no visible change at the choroid level. On the other hand, optical coherence tomography angiography showed the persistence of a vascular occlusion at the retina and choroid level.ConclusionThis is the first case in the optical coherence tomography angiography literature that shows the imaging of toxoplasmic chorioretinal lesions. This case confirms the involvement of the retina and choroid in toxoplasmic uveitis and the disruptive potential of such inflammation. The optical coherence tomography angiography performed after healing showed a persistent ablation of the retina, choriocapillaris, and choroidal vessels. The non-invasive optical coherence tomography angiography imaging technique may have diagnostic and prognostic value in regard to toxoplasmic uveitis.

Cystoid edema, neovascularization and inflammatory processes in the murine Norrin-deficient retina

Mutations in the Norrin (NDP) gene cause severe developmental blood vessel defects in the retina leading to congenital blindness. In the retina of Ndph-knockout mice only the superficial capillary network develops. Here, a detailed characterization of this mouse model at late stages of the disease using in vivo retinal imaging revealed cystoid structures that closely resemble the ovoid cysts in the inner nuclear layer of the human retina with cystoid macular edema (CME). In human CME an involvement of Müller glia cells is hypothesized. In Ndph-knockout retinae we could demonstrate that activated Müller cells were located around and within these cystoid spaces. In addition, we observed extensive activation of retinal microglia and development of neovascularization. Furthermore, ex vivo analyses detected extravasation of monocytic cells suggesting a breakdown of the blood retina barrier. Thus, we could demonstrate that also in the developmental retinal vascular pathology present in the Ndph-knockout mouse inflammatory processes are active and may contribute to further retinal degeneration. This observation delivers a new perspective for curative treatments of retinal vasculopathies. Modulation of inflammatory responses might reduce the symptoms and improve visual acuity in these diseases.

Optical Coherence Tomography Angiography in Eyes with Retinal Vein Occlusion.

Optical coherence angiography (OCTA) is a noninvasive technique that has been introduced in recent years to detect ophthalmological pathology. The growing usage of OCTA to detect retinal abnormalities can be attributed to its advantages over the reference-standard fluorescein angiography (FA), although both of these techniques can be used in association. OCTA's advantages include its dye independency, its ability to produce depth-resolved images of retinal and choroidal vessels that yield images of different vascular layers of the retina, and the better delineation of the foveal avascular zone. OCTA's disadvantages include the lack of normalized patient data, artefactual projection issues, and its inability to detect low-flow lesions or pathologic conditions. Different OCTA platforms use unique algorithms to detect microvasculature, which are implemented in both spectral-domain (SD) and swept-source (SS) OCT machines. Microvascular changes in retinal vein occlusions (RVOs) are visible in both the superficial and deep capillary networks of the retina in OCTA. These visualizations include a decrease in foveal and parafoveal vascular densities, non-perfusion areas, capillary engorgement and telangiectasias, vascular tortuosity, microaneurysms, disruption of the foveal perivascular plexus, and formation of collateral vessels. The restricted field of view and inability to show leakage are important limitations associated with the use of OCTA in RVO cases. In this article, we present a brief overview of OCTA and a review of the changes detectable in different slabs by OCTA in RVO cases published in PubMed and Embase.

The Quantitative Measurements of Vascular Density and Flow Areas of Macula Using Optical Coherence Tomography Angiography in Normal Volunteers.

The quantification of the density of macular vascular networks and blood flow areas in the foveal and parafoveal area in healthy subjects using optical coherence tomography angiography (OCTA). Cross-sectional, prospective study in an institutional setting at the Retina Services of Farabi Eye Hospital. One hundred twelve normal volunteers with no known ocular or systemic disease were included, including patient numbers (one or both eyes), selection procedures, inclusion/exclusion criteria, randomization procedure, and masking. En face angiogram OCTA was performed on a 3 mm × 3 mm region centered on the macula. Automated thresholding and measuring algorithm method for foveal and parafoveal blood flow and vascular density (VD) were used. The density of macular vascular networks and blood flow area in the foveal and parafoveal area were measured. A total of 224 healthy eyes from 112 subjects with a mean age of 36.4 years ± 11.3 years were included. In the foveal region, the VD of the superficial capillary network (sCN) was significantly higher than that of the deep capillary network (dCN) (31.1% ± 5.5% vs. 28.3% ± 7.2%; P < .001), whereas in the parafoveal area, VD was higher in the dCN (62.24% ± 2.8% vs. 56.5% ± 2.5%; P < .001). Flow area in the 1-mm radius circle in the sCN was less than in the dCN. Superficial foveal avascular zone (sFAZ) size was negatively correlated with the VD of the foveal sCN, but in the deep FAZ (dFAZ) was not correlated with VD or blood flow area of the fovea. There was no difference between measured VD and blood flow surface area in both eyes of the subjects. OCTA could be used as a noninvasive, repeatable, layer-free method in quantitative evaluation of VD and blood flow of macular area. The normal quantities of the vascular plexus density and flow will help in better understanding the pathophysiological basis of the vascular disease of retina. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:478-486.].