Radial Peripapillary Research Articles

Global assessment of arteriolar, venular and capillary changes in normal tension glaucoma

Microcirculatory insufficiency has been hypothesized in glaucoma pathogenesis. There is a scarcity of data to comprehensively examine the changes in retinal microvasculature and its role in normal tension glaucoma (NTG). We conducted a cross-sectional case–control study and included 168 eyes from 100 NTG patients and 68 healthy subjects. Quantitative retinal arteriolar and venular metrics were measured from retinal photographs using a computer-assisted program. Radial peripapillary capillary network was imaged with OCT-A and quantitative capillary metrics (circumpapillary vessel density (cpVD) and circumpapillary fractal dimension (cpFD)) were measured with a customized MATLAB program. We found that NTG was associated with decreased arteriolar and venular tortuosity, arteriolar branching angle, cpVD and cpFD. Decreased venular caliber, arteriolar and venular branching angles, cpVD and cpFD were associated with thinner average RNFL thickness. Decreased arteriolar and venular branching angles, cpVD and cpFD were also associated with worse standard automated perimetry measurements (mean deviation and visual field index). Compared with retinal arteriolar and venular metrics, regression models based on OCT-A capillary metrics consistently showed stronger associations with NTG and structural and functional measurements in NTG. We concluded that NTG eyes showed generalized microvascular attenuations, in which OCT-A capillary metrics attenuations were more prominent and strongly associated with NTG.

Normative Data Assessment of Peripapillary and Macular Vessel Density and Foveal Avascular Zone Metrics Using Optical Coherence Tomography Angiography in Children.

To quantify the vessel density of the macula and optic disc and foveal avascular zone (FAZ) in healthy children and to evaluate the effects of age, gender, axial length, body mass index (BMI), and refractive errors on vessel density and FAZ. This study enrolled 92 eyes of 92 participants (42 boys and 50 girls). Optical coherence tomography angiography (OCTA) was performed using AngioVue (Avanti; Optivue). FAZ area, nonflow area, superficial and deep vessel density, FAZ perimeter, acircularity index of FAZ, foveal density, and radial peripapillary capillary vessel density were analyzed by gender. Correlations between the investigated OCTA parameters and age, axial length, and BMI were evaluated. Girls had significantly larger nonflow and FAZ area than boys (P = .01 and .02). Superficial and deep vessel density at the fovea was significantly higher in boys compared to girls (P = .01 and .03). Inferior temporal and superior temporal Radial peripapillary capillary vessel densities were significantly higher in girls than boys (P = .01 and .03). No significant difference was found in the macular and optic disc vessel density measurements within refractive groups (P > .05, for all). Regarding the correlation of age with FAZ and vessel density parameters, only nonflow area was positively correlated with age (r = 0.22, P = .03). This study provides normative data for children. Although boys had greater foveal vessel density, girls had greater FAZ area and nonflow area. Refractive status of the eye and BMI did not influence the OCTA parameters. Although nonflow area was positively correlated with age, other parameters were steady within the ages of 7 to 18 years. [J Pediatr Ophthalmol Strabismus. 2020;57(6):388-398.].

Effect of intraocular pressure lowering on the capillary density of optic nerve head and retinal nerve fiber layer in patients with glaucoma.

To evaluate the effect of IOP lowering on the capillary density of optic nerve head and retinal nerve fiber layer in patients with primary open angle glaucoma. Twenty eyes of 14 glaucomatous patients and 15 eyes of nine normal patients were enrolled. The most appropriate hypotonic treatment was applied to every patient. A HD Angio Disc 4.5 scan (Avanti-AngioVue) was performed at baseline and after a month in the glaucomatous eyes. The following parameters were analyzed: Radial Papillary Capillaries (RPC) density, inside disc, peripapillary, superior-hemi, inferior-hemi, quadrants, and peripapillary, hemi-superior, hemi-inferior, and quadrants RNFL thickness. Optic nerve head analysis was also evaluated. In addition, the RPC density and the RNFL were assessed in the eight sectors provided by the software. The RPC density did not significantly change after IOP reduction (p > 0.05). The inferior-temporal (p = 0.005) and inferior-nasal sectors (p < 0.001) showed a greater capillary density than the respective superior sectors in healthy eyes. In contrast in the glaucomatous eyes, the superior-nasal exhibited greater capillary density with respect to the inferior-nasal sectors. The aggregate RPC density of the inferior sectors was greater than the superior ones in the control group (p < 0.001). An improvement of the average disc area (p = 0.01) and the average cup volume (p = 0.059) were also observed along with increased RNFL thickness at different locations (all, p < 0.05) after IOP lowering therapy was initiated. The glaucomatous eyes presented rarefaction of the radial papillary capillaries density in the inferior sectors, but no significant changes in the density after IOP-lowering medications.

Early vascular modifications after endoscopic endonasal pituitary surgery: The role of OCT-angiography.

PurposeThe aim of the present study is to analyze the changes in retinal vessel density (VD), using Optical Coherence Tomography Angiography (OCT-A), in patients that received endoscopic endonasal approach for the removal of an intra-suprasellar pituitary adenoma compressing optic chiasm.MethodsWe evaluated the VD in Superficial Capillary Plexus (SCP), Deep Capillary Plexus (DCP), Radial Peripapillary Capillary (RPC) and the Foveal Avascular Zone (FAZ) area in a series of fourteen patients (7 males, 7 females, mean age 56 ± 13 years), as compared to healthy controls. We also detected the structural Spectral Domain (SD)-OCT parameters: Ganglion Cell Complex (GCC), Retinal Nerve Fiber Layer (RNFL), visual field parameters (Mean Deviation, Pattern Standard Deviation) and Best Corrected Visual Acuity (BCVA). These measurements were performed prior than surgery and 48 hours after.ResultsThe patients showed a significant decrease in VD of the macular and papillary regions, a significant increase in FAZ area, a significant impairment in SD-OCT, VF parameters and BCVA respect to 14 eyes of 14 healthy controls (p<0.05), at pre-op evaluation. In patients group the VD in SCP, DCP and RPC increased after surgery respect to baseline but the difference turned to be out statistically significant only in RPC (p = 0.003). Also the BCVA (p = 0.040) and the Mean Deviation at visual field (p = 0.015) significantly improved after surgery. While there was a reduction in structural OCT parameters but it was statistically significant only in GCC (p = 0.039). A positive correlation was found between the preoperative VD of the RPC, Mean Deviation, BCVA and the postoperative Mean Deviation (r = 0.426 p = 0.027; r = 0.624 p = 0.001; r = 0.515 p = 0.006).ConclusionOCT-A allows to detect the early changes occurring within 48 hours after surgery showing that the improvement in retinal vessel density could occur before the recovery of the structural OCT parameters and can be a positive predictive factor for the functional recovery.

Follow-up of Nonarteritic Anterior Ischemic Optic Neuropathy With Optical Coherence Tomography Angiography.

Peripapillary and macular microvasculature alterations after nonarteritic ischemic optic neuropathy (NAION) have been investigated in several studies. We aimed to explore the vascular changes from acute NAION (aNAION) to chronic NAION (cNAION). This prospective observational study composed of 16 eyes with aNAION and 40 healthy age-matched controls. Eyes with NAION were followed up for more than 6 months after acute event. Optical coherence tomography angiography (OCTA) was used to evaluate peripapillary and macular vessel densities (VDs). The customized software was used for calculating deep retinal VD to attenuate the large superficial vessel projection effect. The mean age of patients with NAION and controls was 56.13 ± 13.2 and 54.46 ± 15.5 years, respectively (P = 0.195). Radial peripapillary capillary density was significantly lower in both eyes with aNAION and eyes with cNAION than healthy eyes. Peripapillary capillary density decreased significantly from the acute to the chronic phase of NAION with values of 41.77 ± 4.05% and 34.35 ± 7.30%, respectively (P < 0.001). The mean superficial macular VD was 46.83 ± 3.47% in aNAION and 44.49 ± 4.50% in cNAION eyes with no significant difference between them (P = 0.252), but both were lower than control eyes. Deep macular VD was not affected in aNAION and cNAION eyes compared with control eyes. Correlation analysis in eyes with cNAION revealed that there were significant correlations between peripapillary nerve fiber layer and the capillary density (r = 0.772, P < 0.001) and between ganglion cell complex thickness and corresponding superficial macular VD. Although a decrease in peripapillary capillary density in aNAION eyes with active disc edema progressed when evaluated in the cNAION state, progressive VD loss was not observed in the macular area, suggesting a nonprogressive nature of macular vessel involvement in NAION.

Assessment of retinal vascular network in amnestic mild cognitive impairment by optical coherence tomography angiography.

ObjectiveTo assess the presence of retinal vascular network abnormalities in amnestic mild cognitive impairment (aMCI) patients and healthy subjects (HS) through optical coherence tomography angiography (OCTA).MethodsOCTA and SD-OCT were performed in aMCI patients and cognitive normal HS. A complete neuropsychological evaluation was performed. Differences in vessel density (VD) in each retinal vascular plexus and in foveal avascular zone (FAZ) were evaluated with linear mixed model after correction for age, sex and disease duration.ResultsTwenty-seven aMCI patients (10 Single domain aMCI, 17 Multidomain aMCI) and 29 HS were enrolled. aMCI patients showed a statistically significant reduced VD in superficial capillary plexus (SCP), deep capillary plexus (DCP) and an increased FAZ compared to controls. When aMCI patients were divided in single domain (SD) and multiple domains (MD) aMCI, SD aMCI showed no VD differences in SCP, DCP and Radial Peripapillary Capillary, while the FAZ area was significantly larger compared to controls. In MD aMCI, VD values were lower and FAZ was increased compared to controls. Comparing both aMCI groups, MD aMCI showed a significant reduction in VD values of SCP. No correlation was found between mini mental state examination (MMSE) scores and OCTA parameters.ConclusionsOCTA is able to detect changes in retinal microvascular network in early cognitive deficits and, the most sensitive alteration seems to be the enlargement of the FAZ. This non-invasive tool provides useful information on retinal involvement patterns in MCI diagnosis and follow up. Vascular network impairment seems to be related to the number of domains affected and not to MMSE.

Radial peripapillary capillary density in superior segmental optic hypoplasia measured with OCT angiography

BackgroundTo investigate the diagnostic power of radial peripapillary capillary (RPC) density, measured with optical coherence tomography angiography (OCT-A), in patients with superior segmental optic hypoplasia (SSOH).MethodsForty subjects with SSOH and 40 age- and axial length-matched control subjects were retrospectively registered for this study. SSOH was defined as intraocular pressure less than 21 mmHg with the presence of two of the following: superior rim thinning, superior entrance of the central retinal artery, scleral halo, and pale optic disc; as well as non-progressive visual field loss. RPC density was measured with swept-source OCT-A (Triton, Topcon) overall, in the quadrants, and in the 12 clock-wise sectors. Changes in RPC density were also compared in SSOH patients and age-matched patients with mild- or moderate-stage of glaucoma. RPC density was compared in pairs of groups with Welch’s t-test. Diagnostic power was assessed with the area under the receiver operating characteristics curve (AUC).ResultsOverall cpRNFLT was significantly different in the normal (106.7 ± 9.5 μm) and SSOH (77.2 ± 13.7 μm, p < 0.001) subjects. RPC density overall and in the superior, nasal, and inferior quadrants was significantly lower in the SSOH group (all, p < 0.001), but not in the temporal (p = 0.756) quadrant. The diagnostic power of RPC density was highest in the superior quadrant (AUC = 0.928) and the 1 o’clock sector (0.896). Comparing the SSOH and glaucoma patients showed that there were no significant differences in RPC density either overall (p = 0.391) or in the superior quadrant (p = 0.268), while RPC density was significantly higher in the inferior (p = 0.005) and temporal quadrants (p < 0.001) and lower in the nasal quadrant (p = 0.029).ConclusionsLow RPC density was found in the three non-temporal quadrants of the optic nerve head in SSOH patients, in comparison to normal subjects. Regionally, RPC density in SSOH was lower in the nasal quadrant and higher in the inferior and temporal quadrants in comparison to glaucoma patients. Measuring RPC density with OCT-A may help the diagnosis of SSOH and may improve the management of glaucoma.

Quantification of Microvascular Density of the Optic Nerve Head in Diabetic Retinopathy Using Optical Coherence Tomographic Angiography.

Aims To quantify the capillary density of the optic nerve head in healthy control eyes and different stages of diabetic retinopathy (DR) eyes and identify the parameters to detect eyes with or without DR using optical coherence tomographic angiography (OCTA). Methods In this cross-sectional study, 211 eyes of 121 participants with type 2 diabetes with different stages of DR or without DR and 73 eyes of 38 healthy age-matched controls were imaged by OCTA. Radial peripapillary capillary (RPC) plexus density and retinal nerve fiber layer (RNFL) thickness were examined. The mixed model binary logistic regression model was used to identify the parameters to detect eyes with or without DR. The area under the receiver operating characteristic (ROC) curve was calculated. Results RPC density decreased significantly in diabetic patients without DR compared with the healthy controls, and it was negatively correlated with the severity of DR (P < 0.01). RPC density was a significant parameter to distinguish diabetic eyes with or without DR (P < 0.01). The area under the ROC curve was 0.743. Conclusions Quantification of RPC density by OCTA provides evidence of microvascular changes in the optic nerve in diabetic patients. RPC density can serve as a possible biomarker in detecting eyes with DR. Larger cohort studies need to support this statement.

Altered Retinal Perfusion in Patients with Inactive Graves Ophthalmopathy Using Optical Coherence Tomography Angiography

Objective: The aim of this study was to evaluate retinal and optic nerve head (ONH) perfusion in patients with inactive Graves ophthalmopathy (GO) and compare it to healthy controls using optical coherence tomography angiography (OCTA). Methods: Twenty-nine eyes of 29 patients with inactive GO (study group) and 29 eyes of 29 healthy subjects (control group) were included in this study. The vessel density (VD) data in the superficial and deep retinal OCT angiogram of the macula and the radial peripapillary capillary network (RPC) were extracted and analyzed. OCTA was performed using RTVue XR Avanti with AngioVue (Optovue Inc, Fremont, CA). Clinical activity was evaluated using the clinical activity score, the severity assessment using the NOSPECS classification. Results: The VD in the superficial OCT angiogram and in the OCT angiogram of the ONH was significantly lower in the GO group when compared to the control group (whole en face, P = .016; parafovea, P = .026; RPC peripapillary, P = .027). There was no significant correlation between VD and functional parameters or the NOSPECS classification. Conclusion: Macular VD and ONH capillary density measured using OCTA were significantly lower in the study group compared to healthy controls. Noninvasive quantitative analysis of retinal perfusion using OCTA could be useful in monitoring patients with GO. Abbreviations: CAS = clinical activity score; GO = Graves ophthalmopathy; OCTA = optical coherence tomography angiography; ONH = optic nerve head; RPC = radial peripapillary capillary; rSp = Spearman's correlation coefficient; VD = vessel density.

The Detection of Retina Microvascular Density in Subclinical Aquaporin-4 Antibody Seropositive Neuromyelitis Optica Spectrum Disorders

Purpose: To use optical coherence tomography (OCT) and OCT angiography (OCT-A) to measure changes in the retinal structure and microvasculature of patients with aquaporin-4 antibody-positive, neuromyelitis optica spectrum disorder (NMOSD) with a history of optic neuritis (NMOSD+ON) and those without it (NMOSD–ON).Methods: A total of 27 aquaporin-4 antibody-positive NMOSD patients and 31 age- and gender-matched healthy control (HC) participants were included. In 27 NMOSD patients, 19 of them had a history of optic neuritis (ON) and 8 of them had no history of ON. Peripapillary retinal nerve fiber layer (pRNFL) thickness and macular ganglion cell and inner plexiform layer (GCIPL) thickness were measured by OCT. Radial peripapillary capillary density (RPCD) and macular superficial vessel density (MSVD) were measured by OCT-A. Comparisons of retinal structural and microvascular parameters between the cohorts were performed using generalized estimating equation (GEE) models. Diagnostic accuracy was evaluated by the area under the receiver operating characteristics curve (AROC).Results: In NMOSD+ON eyes, the GCIPL and pRNFL thicknesses, 48.6 ± 7.1 and 61.7 ± 25.1 μm, respectively, were significantly thinner than in HC eyes (P < 0.001 for both). However, in NMOSD–ON eyes, the GCIPL and pRNFL thicknesses were not significantly thinner than in HC eyes (P > 0.05 for both). In NMOSD+ON eyes, the RPCD and MSVD, 37.8 ± 7.1 and 36.7 ± 5.0%, respectively, were significantly less dense than HC eyes (P < 0.001 for both). Similarly, the RPCD and MSVD in NMOSD–ON eyes, 49.0 ± 2.8 and 43.9 ± 4.2%, respectively, were also less dense than in HC eyes (P < 0.029 for RPCD, P < 0.023 for MSVD). The highest AROC, 0.845 (sensitivity = 88.5%, specificity = 78.0%), was achieved by the logistic regression combination of all of the variables, i.e., pRNFL, GCIPL, RPCD, and MSVD.Conclusions: Retinal microvascular changes were present in NMOSD–ON eyes. The combination of retinal structural and microvascular parameters might be helpful to discriminate NMOSD–ON eyes from HC eyes.

Assessment of Perfused Peripapillary Capillaries and Peripapillary Capillary Density Maps in Glaucoma Patients.

Introduction:Monitoring and diagnosing glaucoma until 2017 included funduscopy, IOP measurements, gonioscopy, pachymetry, as well as visual field tests, optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). Radial peripapillary capillaries (RPC) can be observed by fluorescein angiography, as well as histologically - superficial and deep capillary layer.Aim:To correlate density of radial peripapillary capillary network (RPC) and retinal nerve fiber layer (RNFL) thickness in eight peripapillary segments in patients with a primary open angle glaucoma (POAG) which have the disease under 10 years of duration, over 10 years of duration and in a group of healthy patients.Methods:This is a cross-sectional review which included three groups of patients: POAG patients under 10 years of disease duration, over 10 years of disease duration and control group of patients. The study is performed on the commercial optical coherence tomography angiography system (AngioVue, Avanti RTVue-XR, Optovue, CA). Sectoral RPC density values, RPC maps and RNFL thickness were analyzed in three groups of patients, data was compared and correlation between parameters was examined.Results:Mean RPC Density values in both superior segments (S1, S2) were significantly lower in patients with glaucoma over 10 years of disease duration compared to patients with glaucoma under 10 years of disease duration (p<0.05). Statistically significant positive correlation was established between RNFL thickness and RPC density in all eight peripapillary segments.Conclusion:Analysis of radial peripapillary capillary network density on optical coherence tomography angiography may provide an earliest functional sign of progressive optic nerve disease and new insights into the pathophysiology of glaucomatous damage.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY DETECTS SUBCLINICAL RADIAL PERIPAPILLARY CAPILLARY DENSITY REDUCTION AFTER PLAQUE RADIOTHERAPY FOR CHOROIDAL MELANOMA.

To evaluate radial peripapillary capillary density (RPCD) in irradiated eyes without radiation papillopathy clinically. Patients treated with plaque radiotherapy for unilateral choroidal melanoma without radiation papillopathy clinically received optical coherence tomography and optical coherence tomography angiography imaging at ∼12- to 24-month follow-up. Comparison of RPCD globally and meridian closest to plaque and meridian farthest to plaque of irradiated versus nonirradiated eyes was performed. Mean age was 55 years (n = 10). Mean largest basal diameter and thickness were 10.1 and 4.4 mm, respectively. Mean radiation dose to the optic nerve head and foveola was 41.7 and 66.2 Gy, respectively. No radiation papillopathy was detected by ophthalmoscopy throughout follow-up (mean:14 months). Radial peripapillary capillary density was significantly reduced globally (all P < 0.02). Meridian closest to plaque RPCD was significantly reduced (P < 0.01), but not meridian farthest to plaque RPCD (P = 0.07). Circumpapillary retinal nerve fiber layer thickness was not significantly reduced (P > 0.26). Radiation dose to the optic nerve head was correlated with meridian closest to plaque RPCD reduction (r = 0.76; P < 0.01). Mean radiation dose to the optic nerve head for <5% and ≥5% RPCD reductions was 35.9 ± 12.2 and 55.2 ± 6.4 Gy, respectively. Radial peripapillary capillary density reduction was found in irradiated eyes before clinical evidence of radiation papillopathy and circumpapillary retinal nerve fiber layer thickness reduction. Radial peripapillary capillary density reduction is correlated to plaque location and radiation dose to the optic nerve head.

Optical coherence tomography angiography characteristics of acute retinal arterial occlusion

BackgroundTo characterize the vascular changes in eyes within the acute phase of retinal arterial occlusion (RAO) by optical coherence tomography angiography (OCT-A) imaging.MethodsThis was a retrospective, observational study. Nineteen patients with RAO (symptom onset within 7 days) and 19 age and sex-matched normal control individuals were included. A comprehensive ophthalmic examination and OCT-A examination were conducted for all the patients.ResultsThe vessel density of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and area with a width of 300 μm around the FAZ (FD-300) was significantly reduced in RAO patients compared with that in the fellow eyes and normal control eyes. The vessel density of the SCP of RAO fellow eyes was significantly lower than that of the normal control eyes (all P < 0.05). Though no difference was observed in the FAZ of RAO eyes compared with that of fellow eyes and normal control eyes, the acircularity index (AI) of the FAZ was significantly increased in RAO eyes (P < 0.05). Central macular thickness (CMT) was correlated with best-corrected visual acuity in central retinal arterial occlusion (CRAO) patients (r = 0.626, P = 0.024). In BRAO eyes, the vessel density of the RAO-affected hemifield was significantly reduced compared with that of the unaffected hemifield (P < 0.05). Radial peripapillary plexus (RPC) vessel density was reduced, accompanied by retinal nerve fiber layer (RNFL) thinning in 3 available CRAO patients.ConclusionsAs a valuable noninvasive imaging tool, OCT-A provides deeper and more detailed vascular information that extends our understanding of the vasculature alterations in acute RAO.

Measurable Aspects of the Retinal Neurovascular Unit in Diabetes, Glaucoma, and Controls

To study the structural and angiographic optical coherence tomography (OCT) data of the macula from controls, patients with diabetes, and patients with glaucoma to evaluate neurovascular and structural relationships. This was a retrospective study of 89 eyes from 49 patients in a community-based retinal referral practice with diabetes, glaucoma, and normal controls. The patients were evaluated with OCT to include retinal nerve fiber layer (RNFL) thickness measurement and ganglion cell layer (GCL) volume determination. The vascular density of the radial peripapillary capillary network and the vascular plexuses in the macula were evaluated with OCT angiography. The main outcome measures were the data obtained per disease state and the interrelationships the data displayed. The mean GCL volumes were significantly lower than the control group in both the diabetic (P= .016) and glaucoma (P < .001) groups. The difference between the diabetic and glaucoma groups was not significant (P= .052). The mean global vascular density was greater in the control group than the diabetic group (P= .002) and the glaucoma group (P < .001). The mean RNFL thicknesses were lowest in the glaucoma group. Both the diabetic and glaucoma groups had significantly lower radial peripapillary network and deep vascular plexus density values compared to controls. Although there are important differences in disease pathogenesis between diabetes and glaucoma, they share certain similarities in the structural and angiographic abnormalities eventually produced. This suggests that, in addition to canonical pathways of disease, a component of both could represent neurodegenerative disease, offering the possibility for the development of new treatments. NOTE: Publication of this article is sponsored bythe American Ophthalmological Society.

Retinal Vascular and Neural Remodeling Secondary to Optic Nerve Axonal Degeneration: A Study Using OCT Angiography

To investigate the pathophysiologic interrelations between retinal neural and vascular changes, detected by spectral-domain OCT (SD-OCT) and OCT angiography (OCTA), resulting from optic nerve axonal degeneration. Institutional, observational, case-control study with prospective enrollment. Twenty-six patients affected by optic nerve axonal degeneration secondary to posterior optic pathway glioma (OPG) involving the chiasma, the postchiasmatic visual pathway, or both (but not involving optic nerves) and 24 gender- and age-matched healthy participants were included consecutively. Best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study score) was measured and SD-OCT (Heidelberg Engineering, Heidelberg, Germany) and OCTA (Nidek RS-3000 Advance device; Nidek, Gamagori, Japan) were performed. Peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell complex (GCC), and inner nuclear layer (INL) were analyzed using SD-OCT. The radial peripapillary capillary plexus, full-thickness peripapillary retina vascularization, and the macular superficial plexus (SCP) and deep capillary plexus (DCP) were analyzed using OCTA. Peripapillary retinal nerve fiber layer and GCC thickness were reduced in eyes affected by OPG (P<0.0001). Radial peripapillary capillary plexus perfusion also was reduced, as well as full-thickness peripapillary retina vascularization (P < 0.01 and P < 0.05, respectively). Macular DCP perfusion was reduced in eyes affected by OPG, whereas macular SCP perfusion did not differ between the 2 groups (P < 0.05 and P > 0.05, respectively). Global pRNFL thickness reduction correlated with the reduction of peripapillary perfusion (P<0.01). Macular GCC thickness reduction did not correlate with SCP reduction (P > 0.05). The reduction of macular DCP perfusion did not correlate with inner nuclear layer thickness (P > 0.05). Retinal neural remodeling secondary to optic nerve axonal degeneration resulting from OPG located at or posterior to the chiasm is accompanied by a secondary retinal vascular remodeling involving not only the peripapillary area, but also the macular area (DCP).

Wide-Field OCT Angiography Investigation of the Relationship Between Radial Peripapillary Capillary Plexus Density and Nerve Fiber Layer Thickness.

PurposeTo characterize the density and distribution of the radial peripapillary capillary plexus (RPCP) and its relationship with retinal nerve fiber layer (NFL) thickness in healthy subjects.MethodsUsing spectral-domain optical coherence tomography (OCT), split-spectrum amplitude decorrelation angiography algorithm and automated montaging, wide-field OCT angiography (OCTA) was used to measure the RPCP capillary density (CD) and NFL thickness. Polar sector-average CD and thickness maps were also created on each eye.ResultsWide-field OCTA (8 × 8 mm) in 10 healthy eyes from 10 subjects demonstrated the distribution of the RPCP throughout the posterior pole. RPCP-CD decreases with distance from the disc, but along the arcuate nerve fiber bundles relatively dense (> half maximum density) RPCP extends more than 5 mm from the disc and includes regions superior to and inferior to the macula. The RPCP-CD and NFL thickness are highly correlated (R2 = 0.85, P < 0.001) and fit well with a nonlinear stacked-layer model. The model fit suggests that the RPCP is present when the NFL is thicker than 17.9 μm and reaches a ceiling area density of 84% and that the RPCP has an apparent volume density of 19% at the current instrument transverse resolution. This indicates that capillary overlap can be expected to occur when NFL thickness reaches 40 μm.ConclusionsThe wide distribution of dense overlapping RPCP suggests that wider (up to 8 mm vertical and 7 mm horizontal) OCTA scans may be better investigate capillary loss in the early stages of glaucoma or other optic neuropathies.

Measurement of Radial Peripapillary Capillary Density in the Normal Human Retina Using Optical Coherence Tomography Angiography.

To image the radial peripapillary capillary (RPC) network with optical coherence tomography angiography (OCTA) and measure its capillary density (CD) in the normal human retina. Fifty-two normal participants underwent OCTA imaging with RTVue XR 100 Avanti OCT. The angioflow enface RPCs network was extracted from OCTA and 8 peripapillary sectors with a sector angle of 45 degrees were selected for quantitative analysis: superior nasal, superior temporal, temporal upper, temporal lower, nasal upper, nasal lower, inferior nasal, and inferior temporal. CD was measured within a 3.4-mm circle diameter around the optic nerve head (ONH) using the Bar-Selective Combination of Shifted Filter Responses method. Using OCTA, the RPC network was visualized with excellent detail as a distinctive pattern of parallel, long, uniform-diameter vessels around ONH, oriented parallel to the retinal nerve fiber layer. The mean overall RPC density within the circle diameter of 3.4 mm around ONH was 0.21±0.053 (95% confidence interval: 0.204-0.216). The CD at the superior temporal (0.243±0.045) and inferior temporal (0.242±0.047) sectors was higher (P<0.05) when compared with the other sectors. Age, sex (P=0.7), and disc size (P=0.3) did not have a significant effect on CD measurement. We imaged and describe a reproducible method to measure the RPC density, which would help us to understand the role of this vascular bed in the functioning of the retinal nerve fiber layer. Our study demonstrated that there was symmetry in superior and inferior corresponding pair sectors with respect to the horizontal meridian and symmetry between paired sectors at the nasal and temporal poles with respect to the vertical meridian.

Visualization of Radial Peripapillary Capillaries Using Optical Coherence Tomography Angiography: The Effect of Image Averaging.

ObjectivesTo assess the effect of image registration and averaging on the visualization and quantification of the radial peripapillary capillary (RPC) network on optical coherence tomography angiography (OCTA).MethodsTwenty-two healthy controls were imaged with a commercial OCTA system (AngioVue, Optovue, Inc.). Ten 10x10° scans of the optic disc were obtained, and the most superficial layer (50-μm slab extending from the inner limiting membrane) was extracted for analysis. Rigid registration was achieved using ImageJ, and averaging of each 2 to 10 frames was performed in five ~2x2° regions of interest (ROI) located 1° from the optic disc margin. The ROI were automatically skeletonized. Signal-to-noise ratio (SNR), number of endpoints and mean capillary length from the skeleton, capillary density, and mean intercapillary distance (ICD) were measured for the reference and each averaged ROI. Repeated measures analysis of variance was used to assess statistical significance. Three patients with primary open angle glaucoma were also imaged to compare RPC density to controls.ResultsQualitatively, vessels appeared smoother and closer to histologic descriptions with increasing number of averaged frames. Quantitatively, number of endpoints decreased by 51%, and SNR, mean capillary length, capillary density, and ICD increased by 44%, 91%, 11%, and 4.5% from single frame to 10-frame averaged, respectively. The 10-frame averaged images from the glaucomatous eyes revealed decreased density correlating to visual field defects and retinal nerve fiber layer thinning.ConclusionsOCTA image registration and averaging is a viable and accessible method to enhance the visualization of RPCs, with significant improvements in image quality and RPC quantitative parameters. With this technique, we will be able to non-invasively and reliably study RPC involvement in diseases such as glaucoma.

Study of the Radial Peripapillary Capillary Network in Congenital Optic Disc Anomalies With Optical Coherence Tomography Angiography

To evaluate the radial peripapillary capillary network with optical coherence tomography angiography (angio-OCT) in morning glory syndrome (MGS), optic disc colobomas, and optic disc pits, and to explore possible correlations between the neural vascular structure and the pathogenesis of congenital optic disc anomalies. Prospective observational comparative case series. Fifteen eyes of 15 patients with congenital optic disc anomalies were enrolled in this study. All patients underwent angio-OCT. The scans were centered on optic discs. The mean age at presentation was 33 years (range: 19-50 years). Congenital optic disc anomalies were identified in all 15 eyes. Three eyes had the characteristic funduscopic signs of MGS, and angio-OCT scans of the peripapillary retina revealed a dense microvascular network. Optic disc colobomas were found in 5 eyes, and the characteristic funduscopic signs of optic pits were found in 7 eyes. Angio-OCT showed the absence of a radial peripapillary microvascular network in these 12 eyes. The finding that angio-OCT scans confirmed the presence of a peripapillary microvascular network only in MGS cases supports the hypothesis that a primary neuroectodermal abnormality and a secondary mesenchymal abnormality leads to MGS. Angio-OCT is a safe, rapid imaging technique that could shed light on the pathogenesis of rare diseases of the optic disc.

Quantitative Optical Coherence Tomography Angiography of Radial Peripapillary Capillaries in Glaucoma, Glaucoma Suspect, and Normal Eyes

To evaluate the quantitative characteristics of the radial peripapillary capillary (RPC) network in glaucoma, glaucoma suspect, and normal eyes using speckle variance optical coherence tomography angiography (OCT-A). To determine correlations between RPC density, nerve fiber layer (NFL) thickness, and visual field indices. Cross-sectional study. OCT-A images of RPCs were acquired at a single institution using a custom-built 1060nm system from 3 groups: unilateral glaucoma (10 eyes from 5 subjects), glaucoma suspects (6 eyes from 3 subjects), and normal control eyes (16 eyes from 9 normal subjects). Peripapillary NFL thickness measurements were determined using spectral-domain optical coherence tomography. Glaucoma and glaucoma suspects also underwent automated 30-2 Humphrey visual field analysis. Manual tracing techniques were used to quantify RPC density in the OCT-A images. Data were analyzed using a linear mixed model with 1 fixed-effect covariate. Correlations between main outcome measures (RPC density, NFL thickness, and visual field index) were determined. Mean age was not significantly different between the 3 groups (P= .25). The density of RPCs was significantly lower in glaucomatous eyes compared with matched-peripapillary regions in the fellow eye, glaucoma suspect group, and normal group (all P < .001). RPC density was strongly correlated with NFL thickness (P < .001) and visual field index (P < .001). Significant reductions in RPC density were correlated with sites of NFL decrease and visual field loss in glaucoma. Speckle variance OCT-A allows visualization and quantification of RPCs and may therefore be a useful tool for indirectly quantifying and monitoring retinal ganglion cell axonal injury in glaucoma.