Identifying Microvascular and Neural Parameters Related to the Severity of Diabetic Retinopathy Using Optical Coherence Tomography Angiography.
ABSTRACT: Purpose:To identify microvascular and neural parameters related to the severity of diabetic retinopathy (DR) by using optical coherence tomography angiography in patients with type 2 diabetes. Methods:This cross-sectional study included 110 eyes (63 patients) with no DR, 46 eyes (33 patients) with mild nonproliferative DR, 36 eyes (23 patients) with moderate nonproliferative DR, 36 eyes (22 patients) with severe nonproliferative DR, and 31 eyes (19 patients) with proliferative DR. The optical coherence tomography angiography images were processed to quantify the foveal avascular zone parameters, macular vessel density (VD), retinal thickness, peripapillary VD, retinal nerve fiber layer thickness, and ganglion cell complex thickness. A LASSO-based continuation ratio model was used to select the most clinically relevant parameters for predicting the stage of DR. Results:The regression model identified a set of regional parameters for each scanning pattern that identified the DR severity, including foveal avascular zone perimeter; FD-300; temporal perifoveal superficial capillary plexus VD and retinal thickness; temporal and nasal parafoveal deep capillary plexus VD; peripapillary VD in the temporal superior, nasal inferior, and temporal inferior sectors; temporal superior and nasal inferior retinal nerve fiber layer thickness; ganglion cell complex thickness; and FLV, which changed significantly with the progression of DR. Furthermore, two combined blocks exhibited different sensitive parameters to differentiate between the groups based on DR severity. Similar results were obtained in eyes without diabetic macular edema. Conclusions:We identified microvascular and neural parameters related to the severity of DR using optical coherence tomography angiography, suggesting their potential clinical application for better screening and staging of DR.
Project description:<h4>Purpose</h4>The purpose of this study was to evaluate differences in optical coherence tomography angiography (OCTA) metrics in the superficial (SCP), intermediate (ICP), and deep (DCP) vascular plexuses across diabetic retinopathy (DR) severity levels.<h4>Methods</h4>This was a cross sectional observational retrospective chart review study. Eligible patients with diabetes who underwent same day RTVue XR Avanti OCTA, spectral-domain optical coherence tomography (SD-OCT), and 200-degree Optos ultrawide field color imaging. SCP, ICP, and DCP vessel density (VD) and vessel length density (VLD) were assessed using 3-D projection artifact removal software (PAROCTA) software.<h4>Results</h4>Of 396 eyes (237 patients), 16.1% had no DR, 26.9% mild nonproliferative DR (NPDR), 21.1% moderate NPDR, 12.1% severe NPDR, 10.1% proliferative DR (PDR) without panretinal photocoagulation (PRP), and 13.4% PDR with PRP. When comparing mild NPDR to no DR eyes, ICP and DCP VD and VLD were significantly lower, but there was no difference for SCP metrics. In eyes with more severe DR, there were significant differences in SCP VD and VLD between DR severity levels (mild versus moderate NPDR: VD 35.45 ± 3.31 vs. 34.14 ± 3.38, P = 0.008 and VLD 17.59 ± 1.83 vs. 16.80 ± 1.83, P = 0.003; moderate versus severe NPDR: VLD 16.80 ± 1.83 vs. 15.79 ± 1.84, P = 0.019), but no significant differences in ICP or DCP.<h4>Conclusions</h4>Although VD of each of the three individual layers decreases with increasing DR severity, DR severity has a substantially different effect on OCTA parameters within each layer. Vascular changes in eyes with no to early DR were present primarily in the deeper vascular layers, whereas in eyes with advanced DR the opposite was observed. This study highlights the effects of ICP and the importance of assessing SCP and DCP changes independently across each DR severity level.
Project description:PURPOSE:To evaluate the correlation between retinal sensitivity in microperimetry (MP) with vessel density (VD) using optical coherence tomography angiography (OCTA) in primary open-angle glaucoma (POAG). METHODS:We enrolled 30 participants (52 eyes) with POAG and 15 participants (23 eyes) in the healthy control group. All participants were examined for retinal structure using OCTA to assess VD and Spectral domain OCT (SD-OCT) to assess ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) thickness. Retinal sensitivity was tested with MP and standard automatic perimetry (SAP). RESULTS:The VD in moderate/severe POAG was lower than that in mild POAG and healthy control in the macular superficial vascular plexus (SVP) (38.7±6.3% vs. 42.9±5.2%, 49.7±2.6% respectively, P<0.001) and peripapillary radial peripapillary capillaries (pRPC) (36.4±5.7% vs. 43.6±6.6%, 49.1±2.4% respectively, P<0.001). The Pearson's correlations between function-structure parameters were strongest with MP average sensitivity threshold and SVP VD in the area of whole macula (r = 0.68); followed by SAP mean deviation (MD) and pRNFL thickness (r = 0.63); SAP MD and pRPC VD (r = 0.59) and MP average threshold and GCC thickness (r = 0.54). We found the AUROCs for discriminating between glaucomatous and healthy eyes were highest for structural parameters as follows: pRNFL (0.94), macular SVP whole (0.92), pRPC (0.92) and GCC (0.91). Pairwise comparison of the above parameters showed no difference (P>0.05). CONCLUSION:The relationship between microvascular damage in the macular SVP whole and the decrease of MP average sensitivity threshold is stronger than the pRNFL thickness measurements and SAP parameters. OCTA and MP techniques are valuable methods that allow clinically monitor structural and functional changes in glaucomatous eyes.
Project description:Although early glaucoma detection is important to prevent visual loss due to disease progression, its clinical diagnosis in highly myopic eyes is still difficult. Many studies using optical coherence tomography (OCT) angiography (OCTA) reported decreased vessel density (VD) in glaucomatous eyes compared to normal eyes. We evaluated the diagnostic ability of peripapillary VD and macular VD measured by OCTA, comparing them with conventional valuables such as peripapillary retinal nerve fibre layer (RNFL) thickness and macular ganglion cell-inner plexiform layer (GCIPL) thickness measured by OCT. We also calculated the average VD ratio (VDR) (average outer macular VD/average inner macular VD), superior VDR (superior outer macular VD/average inner macular VD), and inferior VDR (inferior outer macular VD/average inner macular VD). Totally, 169 eyes from 169 subjects were enrolled. Among OCTA measurements, the best diagnostic parameters were average VDR (AUROC: 0.852 and 0.909) and inferior VDR (AUROC: 0.820 and 0.941) in nonhighly and highly myopic eyes, respectively. Inferior VDR showed better diagnostic ability than most of the other OCT measurements including peripapillary RNFL thickness and macular GCIPL thickness in highly myopic eyes. Accordingly, OCTA measurements can be useful for diagnosing glaucoma in highly myopic eyes, especially when using calculated indices such as average VDR or inferior VDR.
Project description:To quantify changes in retinal microvasculature in diabetic retinopathy (DR) by using spectral-domain optical coherence tomography angiography (SD-OCTA).Retrospective, cross-sectional, observational study of healthy and diabetic adult subjects with and without DR. Retinal microvascular changes were assessed by using SD-OCTA images and an intensity-based optical microangiography algorithm. A semiautomated program was used to calculate indices of microvascular density and morphology in nonsegmented and segmented SD-OCTA images. Microvascular density was quantified by using skeleton density (SD) and vessel density (VD), while vessel morphology was quantified as fractal dimension (FD) and vessel diameter index (VDI). Statistical analyses were performed by using the Student's t-test or analysis of variance with post hoc Tukey honest significant difference tests for multiple comparisons.Eighty-four eyes with DR and 14 healthy eyes were studied. Spearman's rank test demonstrated a negative correlation between DR severity and SD, VD, and FD, and a positive correlation with VDI (? = -0.767, -0.7166, -0.768, and +0.5051, respectively; P < 0.0001). All parameters showed high reproducibility between graders (ICC = 0.971, 0.962, 0.937, and 0.994 for SD, VD, FD, and VDI, respectively). Repeatability (?) was greater than 0.99 for SD, VD, FD, and VDI.Vascular changes in DR can be objectively and reliably characterized with SD, VD, FD, and VDI. In general, decreasing capillary density (SD and VD), branching complexity (FD), and increasing average vascular caliber (VDI) were associated with worsening DR. Changes in capillary density and morphology were significantly correlated with diabetic macular edema.
Project description:PURPOSE:Evaluate and compare the retinal microvasculature in the superficial capillary plexus (SCP) in Alzheimer's disease (AD), mild cognitive impairment (MCI), and cognitively intact controls using OCT angiography. OCT parameters were also compared. DESIGN:Cross-sectional study. PARTICIPANTS:Seventy eyes from 39 AD participants, 72 eyes from 37 MCI participants, and 254 eyes from 133 control participants were enrolled. METHODS:Participants were imaged using Zeiss Cirrus HD-5000 with AngioPlex (Carl Zeiss Meditec, Dublin, CA) and underwent cognitive evaluation with Mini-Mental State Examination. MAIN OUTCOME MEASURES:Vessel density (VD) and perfusion density (PD) in the SCP within the Early Treatment Diabetic Retinopathy Study 6-mm circle, 3-mm circle, and 3-mm ring were compared between groups. Foveal avascular zone (FAZ) area, central subfield thickness (CST), macular ganglion cell-inner plexiform layer (GC-IPL) thickness, and peripapillary retinal nerve fiber layer (RNFL) thickness were also compared. RESULTS:Alzheimer's participants showed significantly decreased SCP VD and PD in the 3-mm ring (P = 0.001 and P = 0.002, respectively) and 3-mm circle (P = 0.003 and P = 0.004, respectively) and decreased SCP VD in the 6-mm circle (P = 0.047) compared with MCI and significantly decreased SCP VD and PD in the 3-mm ring (P = 0.008 and P = 0.004, respectively) and 3-mm circle (P = 0.015 and P = 0.009, respectively) and SCP PD in the 6-mm circle (P = 0.033) when compared with cognitively intact controls. There was no difference in SCP VD or PD between MCI and controls (P > 0.05). FAZ area and CST did not differ significantly between groups (P > 0.05). Alzheimer's participants showed significantly decreased GC-IPL thickness over the inferior (P = 0.032) and inferonasal (P = 0.025) sectors compared with MCI and significantly decreased GC-IPL thickness over the entire (P = 0.012), superonasal (P = 0.041), inferior (P = 0.004), and inferonasal (P = 0.006) sectors compared to controls. MCI participants showed significantly decreased temporal RNFL thickness (P = 0.04) compared with controls. CONCLUSIONS:Alzheimer's participants showed significantly reduced macular VD, PD, and GC-IPL thickness compared with MCI and controls. Changes in the retinal microvasculature may mirror small vessel cerebrovascular changes in AD.
Project description:PURPOSE:To explore the relationships between vessel density (VD) in the retinal vascular plexuses with the thickness and structural changes of their corresponding retinal layers in patients with diabetic retinopathy (DR). METHODS:Retrospective analysis of 17 eyes of 17 Type 1 diabetes (T1D) patients with severe non-proliferative or proliferative DR and no current or past macular edema. Seventeen age- and sex-matched healthy subjects were included as controls. Using optical coherence tomography (OCT) and OCT-angiography (OCTA), VD was measured in the superficial vascular plexus (SVP) and deep vascular complex (DVC) that includes the intermediate (ICP) and deep capillary plexuses (DCP), and compared to the retinal thickness (RT) of the inner (from the inner limiting membrane to the inner plexiform layer) and intermediate (inner nuclear and outer plexiform layer) retinal layers. The correlation between the inner and intermediate RT and the VD of the corresponding vascular networks (SVP and DVC, respectively) was assessed. All OCT and OCTA examinations were performed using the RTVue XR Avanti (Optovue, Fremont, CA). RESULTS:The inner RT and VD in all plexuses were significantly reduced in T1D patients compared to healthy subjects. The capillary drop-out patterns were polygonal and well-defined in the SVP while the ICP and DCP showed a more diffuse capillary rarefaction and a VD that varied in the same proportion. The inner RT significantly correlated with VD in the SVP (r = 0.71 in healthy subjects and r = 0.62 in T1D patients, p <0.01). The intermediate RT did not significantly correlate with VD in the DVC. CONCLUSIONS:In T1D subjects, OCTA allowed observing different capillary drop-out patterns in the SVP and in the ICP-DCP, with different structural changes in the corresponding retinal layers, suggesting that they should be considered as distinct anatomical and functional entities.
Project description:Importance:Projection artifacts in optical coherence tomography angiography (OCTA) blur the retinal vascular plexuses together and limit visualization of the individual plexuses. Objective:To describe projection-resolved (PR) OCTA in eyes with diabetic retinopathy (DR) and healthy eyes. Design, Setting, and Participants:In this case-control study, patients with DR and healthy controls were enrolled in this observational study from January 26, 2015, to December 4, 2015, at a tertiary academic center. Spectral-domain, 70-kHz OCT obtained 3?×?3-mm macular scans. The PR algorithm suppressed projection artifacts. A semiautomated segmentation algorithm divided PR-OCTA into superficial, intermediate, and deep retinal plexuses. Two masked graders examined 3-layer PR-OCTA and combined angiograms for nonperfusion and abnormal capillaries. Main Outcomes and Measures:Retinal nonperfusion and capillary abnormalities and the diagnostic accuracy of detecting DR. Results:Twenty-nine eyes of 15 healthy individuals (mean [SD] age, 36.2 [13.4] years; 11 women) and 47 eyes of 29 patients with DR (mean [SD] age, 55.5 [11.9]; 10 women) underwent imaging. PR-OCTA revealed 3 distinct retinal plexuses in their known anatomical locations in all eyes. The intermediate and deep plexuses of healthy eyes revealed capillary networks of uniform density and caliber, whereas the superficial plexus revealed vessels in the familiar centripetal branching pattern. In eyes with DR, 3-layer PR-OCTA disclosed incongruent areas of nonperfusion and varied vessel caliber and density in the deeper plexuses. Masked grading of capillary nonperfusion on 3-layer PR-OCTA detected DR with 100% sensitivity (95% CI, 90.8%-100%) and 100% specificity (95% CI, 85.4%-100%). With unsegmented retinal angiograms, the sensitivity and specificity were 78.7% (95% CI, 63.9%-88.8%) and 100% (95% CI, 85.4%-100%), respectively (P?=?.002 for sensitivity). On 3-layer PR-OCTA, sensitivity was 72.2% (95% CI, 54.6%-85.2%) for severe nonproliferative DR and proliferative DR eyes with generalized nonperfusion in 2 or more individual plexuses, but on combined angiogram, sensitivity was 25.0% (95% CI, 12.7%-42.5%) for generalized nonperfusion (P?<?.001). PR-OCTA disclosed dilated vessels in the intermediate and deep plexuses in 23 eyes (100%) with proliferative DR, 13 eyes (100%) with severe nonproliferative DR, 8 eyes (73%) with mild to moderate nonproliferative DR, and 0 control eyes. Conclusions and Relevance:By presenting 3 retinal vascular plexuses distinctly, PR-OCTA reveals capillary abnormalities in deeper layers with clarity and may distinguish DR from healthy eyes and severe DR from mild DR with greater accuracy compared with conventional OCTA.
Project description:OBJECTIVE:The study aimed to evaluate the quantitative characteristics of the macular vessel density (VD) and foveal avascular zone (FAZ) in glaucoma using optical coherence tomography angiography (OCT-A). DESIGN:Cross-sectional, age- and sex-matched case-control study. METHODS:Fifty-two eyes of 52 patients with primary open angle glaucoma and 52 eyes from 52 healthy participants were recruited retrospectively. OCT-A was performed on a 3 x 3-mm macular region centered on the fovea. OCT-A scans were manually graded to define the FAZ. Parafoveal VD in superficial and deep retina were analyzed in the circular- and quadrant-segmented zone. The FAZ parameters included size, perimeter, and circularity index. The regression analysis among VD and FAZ-related parameters and ocular parameters was performed, and the diagnostic ability was calculated with refractive error adjusted. RESULTS:For both groups, the mean age and the sex ratio was not different between groups. With refractive error adjusted, the average macular VD was lower in glaucoma than in the control group for superficial (P = 0.013), deep (P<0.001), and the whole retina (P = 0.002). There were increased FAZ perimeter and decreased FAZ circularity index in glaucoma when compared with controls (P<0.001). In the multivariate regression models, FAZ circularity index were significantly associated with decreased peripapillary RNFL thickness (P = 0.007) and macular GCIPL thickness (P = 0.009) measured by OCT. The refractive-error adjusted area under receiver operating characteristics was highest for FAZ circularity index (0.905; 95% CI, 0.844-0.966), followed by temporal deep retinal VD (0.870; 95% CI, 0.803-0.937) and FAZ perimeter (0.858; 95% CI, 0.784-0.932). CONCLUSIONS:Decreased macular VD, increased FAZ perimeter, and decreased FAZ circularity index were observed in eyes with glaucoma using OCT-A. With refractive error adjusted, these parameters showed considerable diagnostic value for glaucoma. FAZ circularity index may be a novel biomarker representing disruption of the parafoveal capillary network in glaucoma, as supported by its association with structural parameters.
Project description:Purpose:The purpose of this study was to evaluate specifically in type 1 diabetes mellitus (DM) individuals the relationship between perifoveal superficial capillary plexus (SCP) parameters assessed by optical coherence tomography angiography (OCTA) and diabetic retinopathy (DR) grade. Methods:Cross-sectional analysis of a large scale prospective OCTA trial cohort (ClinicalTrials.gov NCT03422965). A total of 1186 eyes (593 individuals), 956 type 1 DM eyes (478 patients), and 230 control eyes (115 healthy volunteers) were included in this study. DR stage was graded according to the International Classification. OCTA imaging was performed with a commercially available device (Cirrus HD-OCT). Vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) area, perimeter and circularity measurements were quantified in the SCP and receiver operating characteristic (ROC) curves were constructed for each OCTA parameter. Results:VD and PD (in both 3 × 3 and 6 × 6 mm captures) were inversely associated with DR stage (P < 0.001 in all cases) in a multiple regression analysis after controlling by age, gender, signal strength index, axial length, and DM duration. Greater FAZ area and perimeter and conversely lower circularity measurements were observed as DR severity increased in both scanning protocols (P < 0.05 in all cases). Conclusions:In type 1 DM individuals, OCTA provides an objective, continuous, and reliable method for accurate quantification of VD, PD, and FAZ parameters in the SCP, which ultimately correlate with DR stages. Translational Relevance:Objective OCTA measurements of the retinal microvasculature could substitute the clinical DR classification in patients with type 1 DM, identify patients at risk of DR progression, and inform treatment decisions to modify the evolution of the disease.
Project description:<b>Purpose: </b>To investigate superficial retinal microvascular plexuses detected by optical coherence tomography angiography (OCT-A) in multiple sclerosis (MS) subjects and compare them with healthy controls.<br><br><b>Methods: </b>A total of 92 eyes from 92 patients with relapsing-remitting MS and 149 control eyes were included in this prospective observational study. OCT-A imaging was performed using Triton Swept-Source OCT (Topcon Corporation, Japan). The vessel density (VD) percentage in the superficial retinal plexus and optic disc area (6 x 6 mm grid) was measured and compared between groups.<br><br><b>Results: </b>MS patients showed a significant decrease VD in the superior (p = 0.005), nasal (p = 0.029) and inferior (p = 0.040) parafoveal retina compared with healthy subjects. Patients with disease durations of more than 5 years presented lower VD in the superior (p = 0.002), nasal (p = 0.017) and inferior (p = 0.022) parafoveal areas compared with healthy subjects. Patients with past optic neuritis episodes did not show retinal microvasculature alterations, but patients with an EDSS score of less than 3 showed a significant decrease in nasal (p = 0.024) and superior (p = 0.006) perifoveal VD when compared with healthy subjects.<br><br><b>Conclusions: </b>MS produces a decrease in retinal vascularization density in the superficial plexus of the parafoveal retina. Alterations in retinal vascularization observed in MS patients are independent of the presence of optic nerve inflammation. OCT-A has the ability to detect subclinical vascular changes and is a potential biomarker for diagnosing the presence and progression of MS.