Retinal Flow Density Research Articles

The Preserflo MicroShunt Affects Microvascular Flow Density in Optical Coherence Tomography Angiography.

Intraocular pressure (IOP) lowering surgery has been shown to alter microvascular density in glaucoma patients. The aim of this study is to report changes in retinal flow density (FD) over the course of treatment with the Preserflo MicroShunt, using optical coherence tomography angiography (OCTA). 34 eyes from 34 patients who underwent Preserflo MicroShunt implantation were prospectively enrolled in this study. OCTA imaging was conducted at the superficial (SCP), deep (DCP) and radial peripapillary plexus (RPC) levels. The progression of FD and IOP was assessed at different time points from baseline to six months postoperatively for the entire patient population, as well as disease severity subgroups. The Preserflo MicroShunt achieved a significant reduction in IOP over the course of six months (median: 8 mmHg; p < 0.01). FD values of the SCP and DCP did not show significant fluctuations, even after adjusting for disease severity. FD of the RPC decreased significantly over the course of six months postoperatively from 42.31 at baseline to 39.59 at six months postoperatively (p < 0.01). The decrease in peripapillary FD was strongest in patients with advanced glaucoma (median: -3.58). These observations hint towards dysfunctional autoregulatory mechanisms in capillaries surrounding the optic nerve head in advanced glaucoma. In comparison, the microvascular structure of the macula appeared more resilient to changes in IOP.

Retinal Flow Density Changes in Early-stage Parkinson’s Disease Investigated by Swept-Source Optical Coherence Tomography Angiography

ABSTRACT Background: Parkinson’s Disease (PD) is the second-most common neurodegenerative disease affecting the elderly population. The eye has been referred to as a window to the brain due to its inseparable relationship with the central nervous system. The development of Swept-Source Optical Coherence Tomography (SS-OCT) and Optical Coherence Tomography Angiography (OCTA) technologies has offered us a better imaging modality to study the impact of PD on the retina. Method: Seventy-five eyes of 42 early-stage PD patients and 150 eyes of 75 matched healthy controls were enrolled in the current study. We performed SS-OCT and SS-OCTA to assess retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) + inner plexiform layer (IPL), internal nuclear layer (INL) thickness, and retinal flow density and flow ratio. Results: Our study indicates decreasing superficial and deep flow density in most regions of the retina. Superficial and deep flow parameters were also associated with RNFL, GCL+IPL, and INL thickness. ROC analysis reveals superficial flow density demonstrated an Area Under Curve (AUC) of 0.688, which is greater than deep flow density and retinal thickness measurements. Conclusion: To the best of our knowledge, we are the first study using SS-OCT and SS-OCTA to study superficial and deep retinal flow changes in early-stage PD patients. Our study suggests decreasing retinal flow density provides greater diagnostic power than retinal thickness measurements in the early stage of PD. SS-OCTA parameters could potentially serve as imaging biomarkers in PD diagnosis and staging.

OCT angiography analysis of retinal vessel density in primary open-angle glaucoma with and without Tafluprost therapy

BackgroundPrimary open-angle glaucoma (POAG) is a progressive neurodegenerative disease which leads to irreversible blindness. An elevated intraocular pressure (IOP) is considered to be the main risk factor for the disease progression. It is known that retinal blood flow is altered in POAG eyes. Tafluprost, a prostaglandin analogue which lowers the IOP, has shown to also improve the retinal blood flow in animals.MethodsThe current study therefore evaluated the retinal vessel density in the peripapillary and macular region of POAG patients with normal IOP treated with topical Tafluprost (n = 20) compared to surgically treated patients with normal IOP (n = 22) using optical coherence tomography angiography (OCT-A). The retinal flow density was obtained after binarisation and evaluated in five sectors.ResultsThere was a significantly higher peripapillary flow density in all sectors in Tafluprost treated eyes when compared to post-surgery eyes. The flow density in the inferior sector of the superficial plexus in the macular region was also significantly higher in the Tafluprost group.Conclusions: These results indicate that Tafluprost not only lowers IOP, but may also enhance retinal blood flow in POAG patients with a normal IOP.

Evaluation of Ocular Perfusion in Alzheimer's Disease Using Optical Coherence Tomography Angiography.

There is increasing evidence for the involvement of cerebrovascular factors in Alzheimer's disease (AD). To evaluate retinal and optic nerve head perfusion in patients with AD using optical coherence tomography angiography (OCTA), and to analyze the correlations of quantitative OCTA metrics with AD pathology and vascular cerebral lesions in AD patients. 36 eyes of 36 patients with AD (study group) and 38 eyes of 38 healthy subjects (control group) were prospectively included in this study. OCTA was performed using RTVue XR Avanti with AngioVue. In addition, patients underwent a detailed ophthalmological and neurological examination including Mini-Mental State Examination, cerebral magnetic resonance imaging, and amyloid-β (Aβ) and tau levels in the cerebrospinal fluid (CSF). The flow density in the superficial retinal OCT angiogram of the macula in the study group was significantly lower compared to the control group (p = 0.001). There was a significant correlation between the flow density in the superficial retinal OCT angiogram of the macula, as measured using OCTA, and the Fazekas scale (Spearman's correlation coefficient = -0.520; p = 0.003). There was no significant correlation between the Aβ or tau levels in the CSF and the flow density data. Patients with AD showed a reduced flow density in the radial peripapillary capillaries layer and in the superficial retinal OCT angiogram when compared with healthy controls. The reduced retinal flow density measured using OCTA is not specifically associated with AD pathology but is associated with the vascular cerebral lesions in AD.

Changes in retinal flow density measured by optical coherence tomography angiography in patients with carotid artery stenosis after carotid endarterectomy

The aim of the study presented here was to evaluate retinal and optic nerve head (ONH) perfusion in patients with severe asymptomatic carotid artery stenosis (CAS) compared with healthy controls and to analyze the impact of carotid endarterectomy using optical coherence tomography angiography (OCT-A). 25 eyes of 25 patients with CAS (study group) and 25 eyes of 25 healthy controls (control group) were prospectively included in this study. OCT-A was performed using RTVue XR Avanti (Optovue, Inc, Fremont, California, USA). The flow density data in the superficial and deep retinal OCT-angiogram of the macula and in the radial peripapillary capillary network (RPC) of the ONH were extracted and analyzed. The flow density in the superficial retinal OCT angiogram of the macula and in the ONH were significantly lower in the study group compared with the control group (macula: p = 0.003) (ONH: p = 0.013). The flow density in the ONH improved significantly after carotid endarterectomy (p = 0.004). A reduced flow density was observed in patients with CAS when compared with healthy controls. The flow density also improved after carotid endarterectomy. Quantitative changes in the microvascular density, as measured using OCT-A, could well be useful in the diagnosis of CAS and the evaluation of therapy success.

Retinal flow density by optical coherence tomography angiography is useful for detection of nonperfused areas in diabetic retinopathy.

Fluorescein angiography (FA) has been conventionally used for detection of retinal nonperfused area (NPA) in diabetic retinopathy (DR) in spite of its qualitative evaluation. Optical coherence tomography angiography (OCTA) has been recently reported to be useful for the quantification of retinal vascular disorder in DR. In this study, we examined whether retinal flow density (FD) measurement in OCTA was useful for NPA detection in DR. The study included 41 eyes from 29 patients with DR who underwent FA and OCTA. Regions surrounded by arteries or veins were extracted in the OCTA image, and the FDs in each region were measured by Image J. Furthermore, each region was classified as NPA or perfused area (PA) in FA. The receiver operating characteristic (ROC) curve was prepared by logistic regression analysis of the FD. The AUC (area under the ROC curve) and cutoff value of FD were also calculated. Two hundred fifty-two regions were analyzed and classified into 38 NPA regions and 214 PA regions using FA. FD of each capillary plexus in NPA was significantly smaller than in PA (p< 0.0001). The AUC of total capillary plexus layers (TCP), superficial capillary plexus layer (SCP), and deep capillary plexus layer (DCP) was 0.975, 0.974, and 0.971, respectively. All areas, where the FD was more than the cutoff value (0.07 in TCP), were diagnosed with PA. Three areas with intraretinal microvascular abnormalities (IRMA) were diagnosed as PA despite being below the cutoff value. FD measurement in OCTA is useful for NPA detection in DR.

Optical coherence tomography angiography analysis of macular flow density in glaucoma.

Modifications in ocular blood flow may play a significant role in glaucoma development. Optical coherence tomography angiography (OCT-A) is based on the detection and analysis of the reflection behaviour of motion in a static environment and therefore is able to quantify the retinal flow density. We used this new technology to examine the density of the active flow vasculature in the macular area in glaucoma patients compared to healthy patients. Thirty patients with primary open-angle glaucoma (mean age: 72.6±7.1years) and 21 healthy patients (mean age: 70.3±8.6years) were recruited. Patients received perimetry and OCT measurements of the peripapillary retinal nerve fibre layer thickness (RNFLT) and macular retinal thickness and OCT-A of the macular area in the superficial and deep retinal (DR) plexus. Flow density of the OCT-A scan was calculated by binarisation and quantification of the pixel density. Macular flow density was globally and nasally reduced in glaucoma patients in the superficial (globally: p=0.0203; nasally: p=0.0003) and DR plexus (globally: p=0.0113, nasally: p<0.0001). There was no significant difference between the superficial retina and the DR concerning the flow density. Flow density showed no significant correlation with perimetry results, RNFLT or retinal segment thickness. Patients with glaucoma exhibit a reduced macular flow density measured by OCT-A compared to controls. The independence of the macular flow density of the retinal segment thickness changes could indicate an altered vascular element in patients with glaucoma.

Vascular flow density in pathological myopia: an optical coherence tomography angiography study

ObjectivesTo investigate vascular flow density in pathological myopia with optical coherence tomography (OCT) angiography.DesignA prospective comparative study was conducted from December 2015 to March 2016.SettingParticipants were recruited in Beijing Tongren...