Optical Coherence Tomography Angiography of the Optic Disc; an Overview

Imaging Artifacts and Quality Evaluation with Ultrawide-Field Swept-Source OCTA in Diabetic Retinopathy

PURPOSE

To evaluate the prevalence and types of artifacts in ultrawide-field swept-source optical coherence tomography angiography (SS-OCTA) scans of diabetic retinopathy (DR) patients.

METHODS

This study was a prospective, observational study conducted from May 2022 to October 2022. Participants comprised individuals with proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), no diabetic retinopathy, and healthy controls. SS-OCTA imaging was performed, and a 5-scan composite with a larger field of view (23.5 mm × 17.5 mm) was captured using built-in software. Two experienced ophthalmologists analyzed the images independently, and the image quality and artifact prevalence were recorded and analyzed.

RESULTS

The study included 70 eyes (16 with PDR, 24 with NPDR, 12 eyes of diabetic patients without DR, and 18 healthy eyes) in 70 subjects. Imaging artifacts were observed in a high percentage of eyes, with 98.57% of eyes presenting at least one type of artifact. A significant proportion of eyes (58.57%) exhibited a severe degree of artifacts. The most prevalent artifacts were loss of signal in 63 eyes (90%) and displacement artifact and masking artifact in 43 eyes (61.4%). Patients with more severe stages of DR had higher artifact scores (p < 0.05). Multivariate regression analysis indicated that DR severity was the most important factor influencing artifact scores (p < 0.05).

CONCLUSIONS

In OCTA photos, various artifacts arise at different frequencies. It is crucial to qualitatively evaluate the images to ensure their quality. The results demonstrate that DR severity has a significant correlation with artifact scores.

Towards standardising retinal OCT angiography image analysis with open-source toolbox OCTAVA

Quantitative assessment of retinal microvasculature in optical coherence tomography angiography (OCTA) images is important for studying, diagnosing, monitoring, and guiding the treatment of ocular and systemic diseases. However, the OCTA user community lacks universal and transparent image analysis tools that can be applied to images from a range of OCTA instruments and provide reliable and consistent microvascular metrics from diverse datasets. We present a retinal extension to the OCTA Vascular Analyser (OCTAVA) that addresses the challenges of providing robust, easy-to-use, and transparent analysis of retinal OCTA images. OCTAVA is a user-friendly, open-source toolbox that can analyse retinal OCTA images from various instruments. The toolbox delivers seven microvascular metrics for the whole image or subregions and six metrics characterising the foveal avascular zone. We validate OCTAVA using images collected by four commercial OCTA instruments demonstrating robust performance across datasets from different instruments acquired at different sites from different study cohorts. We show that OCTAVA delivers values for retinal microvascular metrics comparable to the literature and reduces their variation between studies compared to their commercial equivalents. By making OCTAVA publicly available, we aim to expand standardised research and thereby improve the reproducibility of quantitative analysis of retinal microvascular imaging. Such improvements will help to better identify more reliable and sensitive biomarkers of ocular and systemic diseases.

Optical coherence tomography angiography analysis in patients with intracranial hypertension

INTRODUCTION

Evidence on peripapillary microvasculature in intracranial hypertension (IH) after the regression of papilledema is still scarce. The aim of this preliminary study was to determine the association between structural changes in the optic nerve and the retina and peripapillary microvasculature in patients with IIH.

METHODS

We conducted a retrospective study. The study included 39 eyes of 21 patients with IIH. Treatment for IIH and history of obesity were registered from each patient. Moreover, OCT analysis including retinal nerve fiber layer (RNFL) thickness and ganglion cell-inner plexiform layer (GCIPL) thickness, and OCTA analysis including perfusion density (PD) and flux index (FI) of the radial peripapillary capillary plexus were performed.

RESULTS

Correlation analysis revealed a high correlation between GCIPL thickness and peripapillary PD and FI (p < 0,05, r > 0,7), whereas the degree of correlation between RNFL thickness and peripapillary microvascular parameters was low (p < 0,05, r < 0,7). Patients with regressed papilledema had significantly lower GCIPL thickness and peripapillary PD than control subjects (p < 0,05).

CONCLUSION

Peripapillary microvascular measurements are highly correlated with GCIPL thickness in patients with IIH. Moreover, GCIPL thickness and peripapillary PD are significantly inferior in patients with regressed papilledema compared to control group. Thus, we suggested that peripapillary microvascular parameters may be an early indicator of optic nerve atrophy in patients with IIH.

Accuracy of peripapillary OCTA in patients with acute nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

To evaluate the accuracy of peripapillary optical coherence tomography angiography (OCTA) segmentation in eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION) and healthy eyes.

METHOD

In this retrospective study, en face OCTA images of the optic disc of healthy eyes and eyes with unilateral acute NAION were obtained. The disc boundary and radial peripapillary capillary (RPC) segmentation were generated automatically by the instrument software and then corrected by 2 expert investigators. The frequency of segmentation errors and its impact on vessel density and nerve fibre layer (NFL) thickness measurements were evaluated.

RESULTS

Thirty-eight eyes of 38 subjects (18 in the healthy group and 20 in the acute NAION group) were studied. A misidentified disc border was noted in 5 healthy eyes (27.7%) and 19 eyes with NAION (95.0%; p < 0.001). Segmentation error at the RPC level was found in 6 healthy eyes (33.33%) and 19 eyes with NAION (95.0%; p < 0.001). The nerve fibre layer thickness and RPC density did not change statistically significantly after error corrections in both groups.

CONCLUSIONS

Misidentification of disc border and segmentation error of the RPC layer are common in OCTA images of the optic disc. Accuracy of OCTA imaging in disc boundary detection and RPC network segmentation is reduced in edematous optic discs following acute NAION.

Radial peripapillary capillary density as a predictive factor for glaucoma in eyes with ocular hypertension. An observational, comparative, single-centred study

Background: Ocular hypertension (OH) is a condition characterized by elevated intraocular pressure (IOP) exceeding the normal range, without any evident damage to the optic nerve or visual field defects characteristic of glaucoma. It constitutes a significant precursor to the development of glaucoma, a leading cause of irreversible vision loss worldwide. Emerging evidence has shown that microcirculation alterations in eyes with OH could serve as predicting factors to identify eyes at high risk for progression to glaucoma. In view of the above, the purpose of our study is to investigate microcirculation alterations of the radial peripapillary capillary plexus using optical coherence tomography angiography (OCT-A) in patients with ocular hypertension (OH). Methods: A total of 192 eyes were included in this observational, comparative, single-centre study and were divided in two groups: OH eyes and healthy controls. OCT-A was performed to analyze microcirculation characteristics at the peripapillary area. Radial peripapillary capillary density was measured at the total area of the optic disc and at each separate region (superior, inferior, inside). The parameters of age, medical treatment for ocular hypertension, sex and retinal fiber layer thickness were evaluated. Results: Total radial peripapillary capillary density was significantly lower in patients with OH than in healthy controls Concerning the microcirculation characteristics at each separate region of the peripapillary area, the results were as follows: inferior radial peripapillary capillary density was significantly decreased in individuals with OH than in controls, while measurements in the superior peripapillary area and internal optic disc were similar in both groups. Conclusions: Our study indicates decreased radial peripapillary capillary density in eyes with OH. Microcirculation alterations in the inferior peripapillary area could potentially comprise biomarkers for OH progression to glaucoma.

Evaluation of blood vessel network formation and visual field defect in optic disc melanocytoma

AIM

To investigate the association between visual field defects and blood vessel network (BVN) formation in optic disc melanocytomas (ODMs) using optical coherence tomography angiography (OCTA).

METHODS

Single-centre, retrospective case series of 32 eyes of 32 patients with ODM, in which eyes were divided into two groups based on complete and incomplete BVN formations.

RESULTS

OCTA revealed incomplete BVN formation in 16 of 32 ODMs. The location of BVN absence corresponded to the location of hypofluorescence from fluorescein angiography (FA) in 12 (75%) and to the location of visual field defect in 13 (81%) ODMs in the incomplete BVN group. Perimetric indices were significantly worse in the incomplete BVN group than in the complete BVN group. Linear regression of mean deviation (MD) and Visual Field Index (VFI) on the area of BVN absence were statistically significant (p=0.01 and p=0.003, respectively), whereas linear regressions of MD and VFI on the tumour area were not statistically significant (both p=0.09) in the incomplete BVN group.

CONCLUSION

The location of BVN absence within ODMs corresponded to the location of visual field defect and the location of FA hypofluorescence. Visual field defect was more severe in the incomplete BVN group than in the complete BVN group. Visual field defect was more significantly associated with the area of BVN absence than the tumour area.

Analysis of Vessel Density Using OCTA in Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose: To investigate the intraocular vessel density in patients with nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).Methods: Medical records of patients with NAION were retrospectively analyzed. Their age, sex, best corrected visual acuity, color vision results, mean deviation of visual field test were analyzed. Using results of OCT and OCTA that was performed at first visit within 3 weeks of symptom onset, vessel densities in eyes with NAION were evaluated by comparing contralateral unaffected eyes. Furthermore, in only affected eyes, the correlation between visual acuity at the time of diagnosis and anatomical factors such as mean vessel density and retinal nerve fiber layer (RNFL) thickness was investigated.Results: Twenty-five patients (11 males and 14 females) were enrolled in this study and the mean age was 65.92 ± 9.37 years. Whole RNFL thickness in affected eye was significantly lower than that in unaffected eye (<i>p</i> < 0.001). The average peripapillary vessel density was also significantly lower in affected eyes, 45.63% ± 7.60% compared to that in the contralateral eyes, 51.44% ± 3.40% (<i>p</i> = 0.004). In analysis of only 25 affected eyes, there was no significant correlation between each sectoral peripapillary RNFL thickness and vessel density. There was also no significant correlation between the visual acuity and the vessel density and retinal nerve fiber layer thickness in the ischemic peripapillary hemisphere. However, there was a significant negative correlation between the visual acuity and the un-ischemic peripapillary hemisphere with a coefficient of -0.608 (<i>p</i> = 0.001).Conclusions: The higher vessel density of nonaffected sector, the better visual acuity at the time of diagnosis in patients with NAION. Patency of blood supply in the preserved peripapillary intraretinal vessel density sector may affect the visual function.

The Role of Optical Coherence Tomography Angiography in Optic Nerve Head Edema: A Narrative Review

Optic nerve head (ONH) edema is a clinical manifestation of many ocular and systemic disorders. Ocular and central nervous system imaging has been used to differentiate the underlying cause of ONH edema and monitor the disease course. ONH vessel abnormalities are among the earliest signs of impaired axonal transportation. Optical coherence tomography angiography (OCTA) is a noninvasive method for imaging ONH and peripapillary vessels and has been used extensively for studying vascular changes in ONH disorders, including ONH edema. In this narrative review, we describe OCTA findings of the most common causes of ONH edema and its differential diagnoses including ONH drusen.

Prospective Cross-Sectional Study of Repeatability of Peripapillary Capillary Density Measurement Using Optical Coherence Tomography Angiography in Eyes With Optic Nerve and Retinal Vascular Pathology

BACKGROUND

Optical coherence tomography angiography (OCTA) is a new noninvasive imaging modality that provides high resolution images of the optic nerve head and peripapillary retinal capillary vasculature which can be affected by optic nerve or retinal pathologies. High repeatability of peripapillary capillary density measurement using OCTA has been demonstrated in normal eyes and eyes with glaucoma. The purpose of our study was to quantify the repeatability of peripapillary capillary density measurement using OCTA in both normal eyes and eyes with optic atrophy, optic disc edema, and retinal vasculopathy.

METHODS

This prospective cross-sectional study enrolled 31 patients (59 eyes) including 16 eyes with optic nerve pathology (7 with disc edema from papilledema and 9 with optic atrophy), 35 eyes with retinal vascular disease, and 8 normal eyes. All eyes were imaged twice (30 minutes apart) with the Optovue AngioVue OCTA instrument to obtain 4.5 × 4.5 mm peripapillary scans. Scans were considered good quality if signal strength was 6 or greater. The OCTA parameters obtained include the radial peripapillary capillary (RPC) density of the whole disc, inside the disc, peripapillary region, and the 4 quadrants of the disc (superior, nasal, inferior, and temporal). A Student's t test was used to compare means. Intraclass correlation coefficient (ICC) was calculated to measure repeatability.

RESULTS

Repeatability of RPC density measurements for all regions analyzed demonstrated good to excellent repeatability for the whole cohort {ICC for the whole image was 0.915 (95% confidence interval [CI] = 0.855-0.951)}; ICC for the peripapillary region was 0.945 (95% CI = 0.905-0.969). In the subset of eyes with good image quality (i.e., signal strength ≥ 6), ICC was slightly higher for all regions, with excellent repeatability of the peripapillary region (ICC was 0.971 [95% CI = 0.943-0.986]). Conversely, for eyes with poor image quality scans (i.e., signal strength < 6), ICC was lower, corresponding to moderate to good repeatability for most parameters. For the subset of eyes with optic atrophy, disc edema from papilledema or retinal vasculopathy, all had good to excellent repeatability of the vessel density of the entire disc (ICC values were 0.954 [95% CI = 0.804-0.990], 0.921 [95% CI = 0.711-0.982], and 0.895 [95% CI = 0.788-0.951, respectively]) and of the peripapillary region (ICC values were 0.980 [95% CI = 0.904-0.996], 0.966 [95% CI = 0.854-0.993], and 0.916 [95% CI = 0.827-0.961], respectively).

CONCLUSIONS

The peripapillary capillary density measurement obtained using a commercial OCTA instrument is highly repeatable in eyes with optic nerve atrophy, disc edema from papilledema, or retinal vasculopathy.

VASCULAR PERFUSION DENSITY MAPPING USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY COMPARING NORMAL AND OPTIC DISK PIT EYES

PURPOSE

Optic disk pits (ODPs) are typically detected incidentally as small, gray, unilateral, oval-shaped excavation in the temporal optic disk on routine fundus examination. In this cross-sectional retrospective case series, we report optical coherence tomography angiography findings in patients with unilateral ODPs and describe changes in vessel perfusion associated with ODP.

METHODS

A total of eight eyes (four with ODP and four normal contralateral) were included in this study. Patients were excluded if any other optic disk abnormalities were present. Spectral-domain optical coherence tomography angiography (AngioVue; Optovue, Fremont, CA) imaging was conducted to map the vascularization of three layers in the optic nerve over a 4.5-mm × 4.5-mm region. The radial peripapillary capillaries, the nerve head capillaries, and the choriocapillaris were automatically segmented based on the OCT system software, and the capillary perfusion density (CPD) was quantified for each layer. Kruskal-Wallis one-way analysis of variance was used to compare CPD in normal and ODP eyes of four patients with monocular ODP.

RESULTS

Overall, CPD was lower in eyes with ODP compared with the contralateral normal eye in the radial peripapillary capillary (0.4521 ± 0.08 vs. 0.5505 ± 0.03, P = 0.08) and nerve head capillary layers (0.5461 ± 0.08 vs. 0.5989 ± 0.01, P = 0.08). Significantly lower CPD values were associated with ODP eyes in the radial peripapillary capillary layer within the disk (P = 0.04), inferior nasal (P = 0.04), and temporal (P = 0.02) regions and in the nerve head vessel layer within the disk region (P = 0.04). Significantly higher CPD values were associated with ODP eyes in the choriocapillaris layer within the nasal (P = 0.02), superior temporal (P = 0.02), and inferior temporal (P = 0.02) regions. Visual acuity was also decreased in ODP eyes at 0.4 ± 0.3 logarithm of the minimum angle of resolution units (20/50) compared with normal eyes at 0.1 ± 0.1 logarithm of the minimum angle of resolution units (20/25) (P = 0.12).

CONCLUSION

This study demonstrated that the presence of an ODP is associated with decreased vascular density in some regions of the optic disk and reduced visual acuity.

Repeatability of Peripapillary OCT Angiography in Neurodegenerative Disease

Purpose

To assess the repeatability of peripapillary OCT angiography (OCTA) in those with Alzheimer disease (AD), mild cognitive impairment (MCI), Parkinson disease (PD), or normal cognition.

Design

Cross-sectional.

Participants

Patients with a clinical diagnosis of AD, MCI, PD, or normal cognition were imaged. Those with glaucoma, diabetes mellitus, vitreoretinal pathology, and poor-quality images were excluded.

Methods

Each eligible eye of each participant underwent 2 OCTA 4.5 × 4.5-mm peripapillary scans in a single session using a Zeiss Cirrus HD-OCT 5000 with AngioPlex (Carl Zeiss Meditec). The Zeiss software (v11.0.0.29946) quantified measures of perfusion in the radial peripapillary capillary (RPC) plexus in 4 sectors (superior, nasal, inferior, temporal). The average of these sectors was calculated and reported.

Main Outcome Measures

Radial peripapillary capillary plexus perfusion was quantified using 2 parameters: capillary perfusion density (CPD) and capillary flux index (CFI). Intraclass correlation coefficients (ICCs) were used to quantify repeatability. For subjects who had both eyes included, the average values of each scan pair were used to assess interocular symmetry of CPD and CFI.

Results

Of 374 eyes, 46 were from participants who had AD, 85 were from participants who had MCI, 87 were from participants who had PD, and 156 were from participants who had normal cognition. Capillary perfusion density ICC in AD = 0.88 (95% confidence interval [CI], 0.79–0.93), MCI = 0.95 (0.92–0.96), PD = 0.91 (0.87–0.94), and controls = 0.90 (0.87–0.93). Capillary flux index ICC in AD = 0.82 (0.70–0.90), MCI = 0.87 (0.80–0.91), PD = 0.91 (0.87–0.94) and controls = 0.85 (0.79–0.89). There were no significant differences in interocular variation in average CPD and CFI in AD, MCI, or PD (all P > 0.05). Isolated interocular sectoral CPD differences were noted in AD (nasal, P = 0.049; temporal, P = 0.024), PD (nasal, P = 0.036), and controls (nasal, P = 0.016). Interocular differences in CFI in the superior sector in MCI (P = 0.028) and in average CFI for controls (P = 0.035) were observed.

Conclusions

Peripapillary OCTA repeatability in AD, MCI, and PD is good-excellent and similar to those with normal cognition. Insignificant interocular asymmetry in peripapillary OCTA suggests neurodegeneration may proceed uniformly; future studies may reveal the appropriateness of single-eye imaging.

Optical Coherence Tomography Angiography Characteristics and Predictors of Visual Outcomes in Patients With Acute and Chronic Nonarteritic Anterior Ischemic Optic Neuropathy

BACKGROUND

To investigate the correlation between optical coherence tomography angiography (OCTA) characteristics and visual outcomes in patients with acute and chronic nonarteritic anterior ischemic optic neuropathy (NAION).

METHODS

We retrospectively reviewed clinical data and OCTA images of 26 eyes of 26 patients who had been diagnosed with unilateral NAION. OCTA images were acquired from 17 eyes at the acute stage and from 21 eyes at the chronic stage of NAION. We analyzed the peripapillary vessel density (VD) and macular VD in various layers of the retina and choroid for all images. Possible correlations between the OCTA parameters and visual outcomes were investigated.

RESULTS

Among the OCTA parameters for the acute stage of NAION, the temporal peripapillary VD was found to be positively correlated with final visual acuity and visual field with statistical significance (P = 0.039 and 0.009, respectively). In the chronic stage of NAION, both peripapillary and superficial macular VDs were positively correlated with visual outcomes. The nasal perifoveal VD in the superficial capillary plexus (SCP) also had a significant correlation with final visual acuity for both acute and chronic stages (the Spearman correlation coefficient = 0.565 and 0.685, respectively).

CONCLUSIONS

In patients with NAION, significant correlations were found between OCTA parameters and visual outcomes. The temporal peripapillary VD measured during the acute stage was a significant predictor of final visual outcomes. The decreased nasal perifoveal VD in the SCP was strongly associated with poor visual prognosis.

Assessment of Vascular Changes in Patients after Pars Plana Vitrectomy Surgery Due to Macula-Off Rhegmatogenous Retinal Detachment

The aim of this study was to investigate the changes in the retinal capillary plexuses in patients after pars plana vitrectomy (PPV), which is used for the treatment of rhegmatogenous retinal detachment (RRD). In this study, we included the results of 114 patients who underwent PPV after total retinal detachment (RRD; retinal detachment group). It should be kept in mind that to qualify for the study group, there was a condition that retinal detachment be only present in one eye, allowing the fellow healthy eye to be used for the control group, and the study, therefore, did not include cases where retinal detachment occurred binocularly. Optical coherence tomography (OCT) and OCT-A images were taken at 9 ± 2 months (median 10 months) after the surgery, with the study conducted in the years 2017–2019. OCT was used to examine the external limiting membrane (ELM), central macular thickness (CMT) and retinal nerve fiber layer (RNFL), while OCT-angiography (OCT-A) was used to examine the extent of the foveal avascular zone (FAZ) in the deep and superficial capillary plexuses. Changes in the FAZ area of the superficial plexus (SCP) between the study and control groups were analyzed over 346 ± 50 days. In our study, we observed changes in the FAZ area between the RRD and control groups in the SCP (203.65 ± 31.69 μm² vs. 215.30 ± 35.82 μm²; p = 0.28733) and DCP (284.79 ± 35.82 µm² vs. 336.84 ± 32.23 µm²; p = 0.00924). Changes in the RNFL thickness between the study and control groups over 346 ± 50 days were as follows: 90.15 μm vs. 82.44 μm; p = 0.19773. Disruption of the external limiting membrane was observed in 78.95% (90 eyes) of the study group. In the control group, it was undamaged, and no integrity disorder was observed. In the RRD, changes occurred in the FAZ of both the SCP and the DCP, which reduced the extent of this zone, an effect that was more pronounced in DCPs. A better understanding of the anatomical and hemodynamic changes taking place in the retina after macula-off RRD might be helpful in answering the question as to why BCVA in these cases is “only” or “as much as” from 0.4 to 0.1, namely, that it might be related to changes in the neurosensory retina after macular peeling.

OCT-A evaluation of radiation vasculopathy following slotted plaque brachytherapy

PURPOSE

To determine a reliable diagnostic method to reveal and monitor subclinical progression of neural and perineural radiation vasculopathy.

METHODS

A retrospective cross-sectional study, where optical coherence tomography angiography (OCT-A) imaging data was collected and analyzed from 22 consecutive patients that had been treated with circumneural slotted plaque brachytherapy for peripapillary, juxtapapillary, or circumpapillary choroidal melanomas. Pre-operative dosimetry of palladium-103 radiation dose to the optic nerve and fovea were collected. Quantified differences in OCT-A-measured vessel density and length in treated verses untreated contralateral control eyes were collected. Vessel density and length were correlated to radiation dose, plaque slot depth, visual acuity outcomes, and circumpapillary retinal nerve fiber layer thickness.

RESULTS

Patients had post-irradiation follow-up of median 39 months, interquartile range 62 months). The mean optic disc radiation dose was 89.9 Gy ± 39.2 (86.5, 30.8-189.0). In comparison to controls, OCT-A imaging revealed significant differences in radial peripapillary capillary vessel density (18 μm² in case eyes, 34 μm² in control eyes; p < 0.001) and length (10 μm in case eyes, 14 μm in control eyes; p < 0.001). Change in vessel density did not show a significant correlation to radiation dose, slot depth, or visual acuity. However, change in vessel length was significantly correlated to radiation dose (p = 0.049) and change in visual acuity (p < 0.001).

CONCLUSIONS

OCT-A imaging revealed that radial peripapillary capillary vessel density and length were significantly reduced after circumneural irradiation for choroidal melanoma. Therefore, OCT-A imaging can be used to monitor progression of papillary vasculopathy associated with radiation optic neuropathy.

Correlation Between Central Corneal Thickness and Radial Peripapillary Capillary Density, in Patients With Ocular Hypertension

Purpose

To investigate any possible relationship between the central corneal thickness and the radial peripapillary capillary density detected by optical coherence tomography (OCT) angiography in eyes with ocular hypertension.

Materials and methods

In this observational study, 135 eyes were examined. OCT angiography of the optic disc (4.5 mm) and ultrasound corneal pachymetry were performed in all cases. Age, medical treatment for ocular hypertension, sex, and retinal nerve fiber layer thickness were evaluated. The main indices of blood flow were also examined. Spearman correlation coefficients were used to explore the association between two continuous variables.

Results

A directly proportional significance regarding the correlation between central corneal thickness and radial peripapillary network was indicated in eyes with ocular hypertension (p = .036).

Conclusions

Central corneal thickness and radial peripapillary capillary density constitute two essential screening parameters for patients with ocular hypertension.

Spatial distribution of diabetic capillary non-perfusion

OBJECTIVE

To evaluate the distribution of capillary non-perfusion (CNP) in superficial and deep capillary plexuses (SCP and DCP) in eyes with diabetic retinopathy (DR).

METHODS

In this retrospective case series, macular optical coherence tomography angiography (OCTA) images were obtained from eyes with DR without diabetic macular edema (DME). The area of CNP in SCP and DCP was delineated using an automated approach after excluding the foveal avascular zone (FAZ) and major retinal vessels. The distribution and spatial correlation of the CNP in each layer were analyzed.

RESULTS

Forty-three eyes of 27 patients with DR with a mean age of 59.10 ± 9.05 years were included. The mean CNP area in SCP was statistically significantly higher than DCP (0.722 ± 0.437 mm² vs. 0.184 ± 0.145 mm² , respectively, p < .001). There was a statistically significant association between mean BCVA (0.28 ± 0.21 logMAR) and CNP area in DCP (p = .01). After automated subtraction of CNP areas in DCP from SCP, 25.43 ± 15.05% of CNP areas in the DCP had co-localized CNP areas in SCP. The CNP percentage was statistically significantly different between the concentric rings on foveal center, both in SCP and in DCP (both p < .001) showing a decreasing trend from the outer ring toward the center.

CONCLUSION

In DR, SCP is more ischemic than DCP. This is in contrast to the previously described oxygenation-dependent ischemic cascade following acute retinal vascular occlusions. This study provides further insight into the retinal ischemia in DR.

Optical Coherence Tomography Angiography and Structural Analyses of the Pale Optic Discs: Is It Possible to Differentiate the Cause?

Introduction: To compare the optic nerve head (ONH) structure and microvasculature in patients with optic atrophy due to non-arteritic anterior ischemic optic neuropathy (NAION), compressive optic neuropathy (CON), methanol-induced optic neuropathy (MION), and traumatic optic neuropathy (TON) using optical coherence tomography angiography.Methods: In this comparative, cross-sectional study, 32 eyes with NAION, 18 eyes with CON, 32 eyes with MION, 23 eyes with TON, and 55 normal eyes were enrolled. Radial peripapillary capillary (RPC) vessel density, peripapillary retinal nerve fiber layer (RNFL) thickness, disc area, cup volume, and cup/disc area ratio were obtained using the RTVue XR Avanti system (Optovue Inc., Fremont, CA, USA).Results: RPC vessel density and peripapillary RNFL thickness in all patients were significantly lower than normal subjects. A positive correlation was found between the RPC vessel density and peripapillary RNFL thickness in normal subjects and all study groups. The positive correlation between the inside and outside disc RPC vessel density was only found in the NAION (r = 0.36, P = .042) and MION (r = 0.42, P = .018) groups. No significant difference was found among the groups in terms of peripapillary and inside disc vascular densities (all P > .05). Disc area and cup volume in patients with MION was larger than the values in patients with NAION (P = .018) and TON (P = .044) and normal subjects (P = .015). The discriminating features among the study groups were the larger cup volume and cup/disc area ratio in patients with MION, and lower RNFL thickness in patients with TON.Conclusions: There was a positive correlation between the RNFL thickness and peripapillary RPC vessel density regardless of the cause of optic disc pallor. Structural evaluation of the ONH seems to be a better way to differentiate the cause of optic nerve head atrophy than the microangiographic changes.

Artifacts in Optical Coherence Tomography Angiography

We performed a comprehensive search of the published literature in PubMed and Google Scholar to identify types, prevalence, etiology, clinical impact, and current methods for correction of various artifacts in optical coherence tomography angiography (OCTA) images. We found that the prevalence of OCTA image artifacts is fairly high. Artifacts associated with eye motion, misidentification of retinal layers, projections, and low optical coherence tomography signal are the most prevalent types. Artifacts in OCTA images are the major limitations of this diagnostic modality in clinical practice and identification of these artifacts and measures to mitigate them are essential for correct diagnosis and follow-up of patients.

Quantitative assessment and determinants of the papillary microvasculature in healthy subjects

BACKGROUND

It is critical to monitor the optic disc's vessel density using Optical coherence tomography angiography (OCTA) and evaluate its determinants. In the current study, we investigate the superficial vessel density (VD) of the papillary microvasculature and its determinants in healthy subjects of Southern China.

METHODS

This was a prospective, cross-sectional study. Superficial VD in healthy individuals' optic disc region was measured by OCTA. The factors associated with ocular and systemic parameters were analyzed using a generalized estimation equation (GEE) model.

RESULTS

A total of 510 eyes of 260 healthy subjects were analyzed in the study. The total VD in the optic disc area was 17.21 ± 2.15 mm- 1 (95% CI, 17.02-17.40 mm- 1). The VD in the inner ring and the outer ring of the optic disc were significantly higher compared with the central ring, while the VD of the superior quadrant and inferior quadrant was significantly higher compared with the temporal and nasal quadrant. After adjusting for the ocular factors and systemic factors, AL (β = - 0.4917, P = 0.0003), disc area (β = - 0.3748, P = 0.0143), CMT (β = - 0.0183, P = 0.0003) and SSI (β = 1.0588, P < 0.001) were significantly associated with total VD of the optic disc.

CONCLUSION

The mean total VD in the optic disc area was 17.21 ± 2.15 mm- 1 in healthy subjects, and the superior and inferior VD was significantly higher than the temporal and nasal VD. AL, disc area, CMT, and SSI may affect the total VD in the optic disc area and should be considered in clinical practice.

Ginkgo Biloba affects microvascular morphology: a prospective optical coherence tomography angiography pilot study

PURPOSE

To analyze the vascular morphology changes after consumption of Ginkgo biloba in healthy volunteers by optical coherence tomography angiography (OCTA).

METHODS

Sixty healthy volunteers without systemic and ocular disease were included in this prospective pilot study. After receiving the informed consent of the volunteers, Ginkgo biloba extract (120 mg oral capsule) was administered to sixty volunteers for 4 weeks, once a day in the morning. The main outcome measures were the difference between before and after four-week of consumption in best-corrected visual acuity (BCVA), retinal nerve fiber layer (RNFL) and subfoveal choroidal thickness (sfCT) with optical coherence tomography; whole, foveal, parafoveal and perifoveal regions' superior and deep macular vascular plexus vessel density, foveal avascular zone area (FAZ), FAZ perimeter (PERIM), vessel density in a 300 µm wide region around FAZ (FD-300), choroidal and outer retinal flow area, radial peripapillary capillary (RPC) vascular density of whole, inside the disc, peripapillary and four quadrants with OCTA.

RESULTS

The study group consisted of sixty eyes of 32 women and 28 men with a mean age of 20.57 ± 1.16 years. In post-consumption measurements, peripapillary and superior, inferior, temporal quadrant RPC vascular density (%) was statistically significantly higher than pre-consumption measurements (p 0.020, p 0.021, p 0.008 and p 0.014, respectively). No significant difference was observed for BCVA, sfCT, other macular or RPC vascular density and flow area OCTA parameters between measurements.

CONCLUSION

Four-week consumption of Ginkgo biloba leads to vascular morphological changes in RPC. Further clinical studies are needed to demonstrate its use and effects/benefits in glaucoma, optic neuropathy and other diseases affecting the optic nerve.

Multimodal Imaging of Large Optic Disc Coloboma: A Report of Three Cases

Optic disc coloboma (ODC) is a rare congenital anomaly of the optic nerve. Optical coherence tomography (OCT) helps to monitor the complications when there is associated retinoschisis, retinal detachment, or peripapillary neovascularization, while being minimally invasive. OCT angiography could help to better understand this entity from a vascular perspective. We report multimodal imaging of 3 children with large ODC associated with cat eye syndrome, CHARGE syndrome (coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities), and branchio-oculo-facial syndrome.

Chorioretinal Side Effects of Therapeutic Ocular Irradiation: A Multimodal Imaging Approach

Radiation chorioretinopathy, radiation maculopathy, and radiation optic neuropathy are the major complications of ophthalmic radiotherapy. Optical coherence tomography (OCT) and OCT angiography (OCTA) are revolutionary imaging methods, allowing the visualization of the retinal cellular architecture and the retinal vascular system, respectively. In recent years this multimodal imaging approach has been applied to several retinal disease, but its role in the clinical characterization of retinal complications secondary to ophthalmic radiotherapy has not yet been defined. The purpose of this review is to critically evaluate the role of OCT and OCTA in the clinical assessment of radiation-induced chorioretinopathy, maculopathy, and optic neuropathy.

Quantification of vascular and neuronal changes in the peripapillary retinal area secondary to diabetic retinopathy

PURPOSE

To investigate and quantify peripapillary vascular and neuronal changes secondary to diabetic retinopathy, using spectral-domain optical coherence tomography (OCT) and OCT angiography (OCTA).

DESIGN

This was a cross-sectional study.

METHODS

51 eyes of 51 patients affected by non-proliferative diabetic retinopathy (NPDR) and 19 age-matched healthy control eyes underwent full ophthalmic examination, including OCT and OCTA in the peripapillary area. Vessel area density (VAD), vessel length fraction (VLF) and vessel diameter index (VDI) were quantified in a ring-shaped region of interest of each OCTA image. Capillaries and larger vessels were separately analysed. The thickness of the peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell complex (GCC) was also analysed.

RESULTS

VAD and VLF of peripapillary capillaries were significantly reduced in NPDR eyes, along with the progression of NPDR (p<0.05). VDI was significantly reduced in mild (p=0.0093) and moderate (p=0.0190) NPDR eyes, but not in severe NPDR (p=0.0841). Larger peripapillary vessels showed a significant increase of both VAD and VDI in NPDR eyes. pRNFL and GCC thickness decreased in NPDR eyes, reaching statistical significance only for GCC. No statistically significant correlation was found between perfusion parameters and pRNFL and GCC thickness.

CONCLUSIONS

Retinal capillary remodelling in NPDR involves the peripapillary vascularisation too, as confirmed by OCTA quantitative parameters. The peripapillary macrovasculature and microvasculature need to be separately evaluated. The lack of direct correlation between peripapillary capillaries changes and the loss of retinal nerve fibres suggests that neuronal damage cannot be simply considered secondary to the microvascular one.

Optical coherence tomography angiography (OCTA) applications in ocular oncology

Optical coherence tomography angiography (OCTA) is a revolutionary method in the visualization of the vascular system in different retinal and choroidal layers. During the last 4 years since the commercial availability of different OCTA devices, attempts have been made to utilize this technology in various aspects of ocular oncology from the differentiation of benign and malignant lesions to assisting in evaluation of post-treatment complications, such as radiation retinopathy. However, current OCTA technology is restricted by various artefacts and inherent limitations, some of which are more pronounced in the presence of elevated tumoural lesions. Imminent advancements in OCTA systems and image acquisition processes promise a great potential for application of OCTA in ocular oncology.

Stepwise segmentation error correction in optical coherence tomography angiography images of patients with diabetic macular edema

Aim:

To determine the minimum number of optical coherence tomography B-scan corrections required to provide acceptable vessel density measurements on optical coherence tomography angiography images in eyes with diabetic macular edema.

Methods:

In this prospective, noninterventional case series, the optical coherence tomography angiography images of eyes with center-involving diabetic macular edema were assessed. Optical coherence tomography angiography imaging was performed using RTVue Avanti spectral-domain optical coherence tomography system with the AngioVue software (V.2017.1.0.151; Optovue, Fremont, CA, USA). Segmentation error was recorded and manually corrected in the inner retinal layers in the central foveal, 100th and 200th optical coherence tomography B-scans. The segmentation error correction was then continued until all optical coherence tomography B-scans in whole en face image were corrected. At each step, the manual correction of each optical coherence tomography B-scan was propagated to whole image. The vessel density and retinal thickness were recorded at baseline and after each optical coherence tomography B-scan correction.

Results:

A total of 36 eyes of 26 patients were included. To achieve full segmentation error correction in whole en face image, an average of 1.72 ± 1.81 and 5.57 ± 3.87 B-scans was corrected in inner plexiform layer and outer plexiform layer, respectively. The change in the vessel density measurements after complete segmentation error correction was statistically significant after inner plexiform layer correction. However, no statistically significant change in vessel density was found after manual correction of the outer plexiform layer. The vessel density measurements were statistically significantly different after single central foveal B-scan correction of inner plexiform layer compared with the baseline measurements (p = 0.03); however, it remained unchanged after further segmentation corrections of inner plexiform layer.

Conclusion:

Multiple optical coherence tomography B-scans should be manually corrected to address segmentation error in whole images of en face optical coherence tomography angiography in eyes with diabetic macular edema. Correction of central foveal B-scan provides the most significant change in vessel density measurements in eyes with diabetic macular edema.

Retinal Microvasculature Changes After Repair of Macula-off Retinal Detachment Assessed with Optical Coherence Tomography Angiography

Objective

To characterize the microvascular retinal changes after repair of macula-off rhegmatogenous retinal detachment (RRD) using optical coherence tomography angiography (OCT-A).

Patients and Methods

A retrospective review of patients who underwent repair of macula-off RRD. Fellow unaffected eyes were used as controls. Post-operative OCT-A allowed comparison of vessel density (VD) and foveal avascular zone (FAZ) area in the superficial and deep retinal capillary plexus (DCP) as well as VD in the choriocapillaris layer.

Results

Seventeen eyes of 17 RRD patients were included in the final analysis. There was a reduction in VD of the deep retinal capillary plexus in affected eyes compared to fellow eyes (p = 0.046). RRD eyes with reduced VD in DCP compared with their fellow control eyes had worse visual acuity after repair compared to those without (p = 0.032). No significant microvasculature changes were detected in the FAZ area and VD in the superficial capillary plexus and choriocapillaris compared to fellow eyes.

Conclusion

In macula-off RRD eyes, significant microvascular changes were detected in the DCP using OCT-A even after successful anatomical repair. Decreased VD in the DCP compared to the fellow healthy eyes was correlated with worse visual acuity.

Oral medications for central serous chorioretinopathy: a literature review

Central serous chorioretinopathy (CSCR) is characterised by acute or chronic neurosensory detachments of the retina, usually in the posterior pole, with or without associated detachments of retinal pigment epithelium. Although the condition often resolves spontaneously, chronic and recurrent cases can lead to significant visual loss in the working population and it is thus increasingly recognised as an important public health issue. The uncertainty regarding the underlying cause of CSCR has led to a wide range of therapies being tried for this condition including photodynamic therapy, laser photocoagulation, anti-VEGF injections and a multitude of oral agents. This article aims to review the current evidence for oral agents that have been used for treatment of CSCR. A systematic literature search was conducted for articles published between 1980 to July 2018. A total of 73 articles were included. These studied the following oral medications: eplerenone, spironolactone, beta blockers, H. pylori agents, omeprazole, rifampicin, methotrexate, aspirin, acetazolamide, mifepristone, melatonin, finasteride, ketoconazole, antioxidants and curcumin phospholipid. Although none of the studies showed robust evidence of efficacy, the mineralocorticoid receptor antagonists, particularly eplerenone, appear to demonstrate the highest quality evidence for use in this condition. The review aims to give the reader an overview of the current available evidence for oral medications used in the treatment of CSCR in order to provide an evidence-based discussion with the patient and guide through possible options for treatment.

Widefield optical coherence tomography angiography in diabetic retinopathy

AIMS

To evaluate superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) perfusion in macular and near/mid periphery regions in diabetic patients using widefield swept-source optical coherence tomography angiography (WSS-OCTA).

METHODS

Ninety-four diabetic patients (94 eyes) classified as diabetics without diabetic retinopathy (no DR) (25 eyes), mild DR (23 eyes), moderate/severe DR (26 eyes), proliferative DR (20 eyes) and a control group of 25 healthy subjects (25 eyes) were imaged with the WSS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). Quantitative analysis was performed in the macular and peripheral regions. The main outcome measures were perfusion density (PD) and vessel length density of SCP, DCP and CC.

RESULTS

Peripheral retina (all sectors) showed lower SCP and DCP PD compared to the macular region (p  < 0.001). In diabetics without DR and DR in different stages, SCP and DCP PD significantly decreased at advancing stages of DR (p  < 0.001). At DCP level, central PD was significantly directly related to peripheral PD (superior, R = 0.682 and 0.479; temporal, R  = 0.918 and 0.554; inferior, R  = 0.711). A good sensitivity and an excellent specificity were found in terms of prediction of disease worsening, especially for central and temporal sectors in all plexuses and for all sectors both central and peripheral of DCP.

CONCLUSIONS

The widefield OCTA is useful for the study of central and peripheral retina in diabetic patients with or without diabetic retinopathy, assessing good correlation between central and peripheral retina.

The vascular densities of the macula and optic disc in normal eyes from children by optical coherence tomography angiography

PURPOSE

This study aims to describe the variation and characteristics of vessel density (VD) of the macula and optic disc in the normal eyes of children.

METHODS

This was a retrospective study where subjects aged 5-18 years with normal eyes were enrolled. The macula and optic disc were scanned by optical coherence tomography angiography (OCTA). The influences of age, gender, and axial length (AL) on VD were analyzed.

RESULTS

A total of 71 normal eyes from 71 subjects were enrolled. For the macula, the mean VD of fovea, parafovea, and perifovea at superficial retina and deep retina were 20.1%, 50.2%, 49.4%, 36.1%, 53.9%, and 48.1%, respectively. The mean foveal avascular zone (FAZ) was 0.277 mm². For optic disc, the mean VD of radial peripapillary capillary (RPC) and inside-disc areas were 51.8% and 51.7%, respectively. Significant differences were found between the superior-hemi and inferior-hemi VD of the superficial retinal parafovea, deep retinal perifovea, and perifovea. The fovea VD of the superficial and deep retina and FAZ areas were different between genders. The inside-disc VD was positively correlated with AL, while other VDs had no significant correlation with age and AL.

CONCLUSIONS

The parafovea VD of the superficial retina, parafovea, and perifovea of the deep retina had superior-hemi VD; boys had a higher fovea VD and smaller FAZ area than those of girls, the macular VD and peripapillary RPC density were steady for 5-18 year-olds. This study provided useful information for furthering the understanding of the development mode of vessel in children and the OCTA clinical applications in children.

OCT angiography of persistent hyaloid artery: a case report

Background

A persistent hyaloid artery is a rare fetal remnant. Several complications such as amblyopia, vitreous hemorrhage, and retinal detachment have been reported. Here, we present a case of vitreous hemorrhage with a persistent hyaloid artery.

Case presentation

A healthy 16-year-old male presented with blurred vision in his left eye. Vitreous hemorrhage occurred and absorbed spontaneously. Slit-lamp examination demonstrated a Mittendorf’s dot and fundus examination revealed a persistent hyaloid artery. Optical coherence tomography (OCT) showed a Bergmeister’s papilla. The blood flow of the persistent hyaloid artery via the Bergmeister’s papilla was found by OCT angiography.

Conclusion

The persistent hyaloid artery should be considered as a cause of spontaneous vitreous hemorrhage of young healthy patient. The OCT angiography will be a useful noninvasive approach to confirm the patency of the persistent hyaloid artery.

Leber's hereditary optic neuropathy: Severe vascular pathology in a severe primary mutation

The purpose of the present article was to evaluate the previously unreported vascular alterations in Leber's Hereditary Optic Neuropathy (LHON) 3460 mitochondrial DNA (mtDNA) mutation. Among the three primary mtDNA mutations, namely 11778, 14484, and 3460, LHON 3460 is the most rare and historically recognized as having the poorest visual prognosis. Optical coherence tomography angiography (OCTA) is a novel imaging modaility providing high-resolution microcirculation maps and enhancing visualization of the optic disc and peripapillary capillary beds. We herein exploit the advantages of OCTA, for the first time, to assess the optic nerve head and peripapillary microvasculature changes in an affected patient and compare these vascular changes with an asymptomatic carrier for LHON 3460, serving as a control. Vascular changes in LHON 11778 and 14484 have classically shown microvasculature attenuation localized specifically to the temporal peripapillary quadrant. In the present case, however, OCTA in LHON 3460, the most severe of the three mutational subtypes, illustrated significant vascular attenuation involving the nasal peripapillary region in addition to the temporal peripapillary microvascular changes classically seen in LHON. Our findings suggest that vascular measures may serve useful for objectively assessing mitochondrial disease. Further OCTA studies involving the nasal peripapillary region may be warranted to further understand vascular pathogenesis in LHON.

Repeatability and Reproducibility of Quantification of Superficial Peri-papillary Capillaries by four Different Optical Coherence Tomography Angiography Devices

This study was performed to test the repeatability and reproducibility of measurements of peri-papillary capillaries from four optical coherence tomography angiography (OCTA) devices. 109 healthy eyes were imaged with four OCTA devices (Spectralis, Optovue, Triton and Cirrus). A 3 × 3 mm scan pattern centered on the disc was repeated twice by each device. En face images of superficial capillary plexus were screened and processed for calculation. Vessel length density (VLD) was calculated on four equally divided parts of a ring between two concentric circles manually centered on the disc. General linear model (GLM) was used to test the impact of device and location on VLD. Intraclass correlation coefficient (ICC) of VLD between repeated scans was calculated. Of 218 acquisitions, 36%, 92%, 76% and 88% were eligible for analysis from Spectralis, Optovue, Triton and Cirrus, respectively. ICC was 0.94, 0.90, 0.84 and 0.87 for the four devices. GLM showed measurements significantly varied among devices (P < 0.001) and locations (P < 0.001). Pairwise comparison showed Triton = Spectralis >Optovue >Cirrus, and temporal = nasal >superior = inferior in measuring capillary VLD. This study revealed the repeatability of measuring peri-papillary capillaries was high for all four devices, while the reproducibility among the machines was unfavorable.

Principles of OCTA and Applications in Clinical Neurology

PURPOSE OF REVIEW

The article reviews the recent findings on the use of optical coherence tomography angiography (OCTA) in neurology.

RECENT FINDINGS

OCTA is a new addition to the powerful and complementary technology of the OCT. Due to its noninvasiveness, and reproducibility, it is possible to obtain high-resolution 3D images of the vessels of the human eye. As the vessels of the retina with the presence of endothelial cell's tight junctions resemble the brain vessels, it was hypothesized that the imaging of the retinal vessels might bring insight into brain vessels. OCTA has been effectively used to predict retinal vessel abnormalities in dementia, demyelization, optic disc neuropathies, and inherited degenerative diseases. Most common findings were decrease of vascular density and flow and an increase of avascular zones. Although OCTA is a relative new technology, recent studies show that it can be successfully applied in neurology.

Quantitative analysis of optical coherence tomographic angiography (OCT-A) in patients with non-arteritic anterior ischemic optic neuropathy (NAION) corresponds to visual function

Purpose

Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common cause of non-glaucomatous optic neuropathy in older adults. Optical coherence tomographic angiography (OCT-A) is an emerging, non-invasive method to study the microvasculature of the posterior pole, including the optic nerve head. The goal of this study was to assess the vascular changes in the optic nerve head and peripapillary area associated with NAION using OCT-A.

Design

Retrospective comparative case series.

Methods

We performed OCT-A in 25 eyes (7 acute and 18 non-acute) in 19 patients with NAION. Fellow, unaffected eyes were analyzed for comparison. Patent macro- and microvascular densities were quantified in the papillary and peripapillary regions of unaffected, acutely affected, and non-acutely affected eyes and compared across these groups according to laminar segment and capillary sampling region, and with respect to performance on automated visual field testing.

Results

In acutely affected eyes, OCT-A revealed a reduction in the signal from the major retinal vessels and dilation of patent superficial capillaries in the peripapillary area. By contrast, non-acutely affected eyes showed attenuation of patent capillaries. The peripapillary choriocapillaris was obscured by edema in acute cases, but was similar between non-acute and unaffected eyes. The degree of dilation of the superficial microvasculature in the acute phase and attenuation in the non-acute phase each correlated inversely with visual field performance. The region of reduced patent capillary density correlated with the location of visual field defects in 80% of acute cases and 80% of non-acute cases.

Conclusions

OCT-A reveals a dynamic shift in the superficial capillary network of the optic nerve head with strong functional correlates in both the acute and non-acute phases of NAION. Further study may validate OCT-A as a useful adjunctive diagnostic tool in the evaluation of ischemic optic neuropathy.

Optical coherence tomography angiography at the acute phase of optic disc edema

Background

The differential diagnosis of optic disc edema at the acute phase can be challenging. OCT angiography (OCTA) is a new technology allowing the visualization of the peripapillary vascular network and optic disc capillaries. The peripapillary network alterations of glaucoma and chronic non-arteritic anterior ischemic optic neuropathy (NAION) were reported. However, no OCTA studies on acute optic disc edema from various causes. The aim of this project was to use OCTA to demonstrate the vascular changes the optic nerve head of various types of optic disc edema at the acute phase.

Methods

In this retrospective study, patients with non-arteritic anterior ischemic optic neuropathy (NAION), papillitis or papilledema were recruited. Each patient was imaged using the AngioPlex™ CIRRUS™ HD-OCT device(model 5000, Carl Zeiss Meditec, Inc., Dublin, USA) with a scanning area of 6 × 6 mm² centered on the optic disc. A morphological analysis of the peripapillary network was performed. For some patients with unilateral optic disc edema, a quantitative analysis was performed using a swept-source OCT-A system (PLEX® Elite 9000, Carl Zeiss Meditec, Inc., Dublin, USA). Vessel perfusion density and flux index of the peripapillary area were calculated.

Results

Eight eyes with NAION (4 patients), 12 eyes with papillitis (6 patients) and 25 eyes with papilledema (13 patients) were imaged. The apparent disappearance or moderate pattern alteration of the peripapillary capillary vessels were observed in patients with NAION or papillitis, respectively. For papilledema, the capillaries at the surface of the optic disc were dilated and tortuous, but no peripapillary network pattern changes were observed. The quantitative analysis did not show any difference of peripapillary network between NAION and healthy eyes. For papillitis, the flux index was higher in inflammatory eyes compared to the healthy eyes in average (p = 0.03).

Conclusion

At the acute phase, the morphological analysis of OCT-A appeared to be more useful than the quantification analysis, facilitating the differentiation between the three kinds of ONH edema: ischemic, inflammatory and papilledema.

Peripapillary vascular changes in radiation optic neuropathy: an optical coherence tomography angiography grading

AIMS

To investigate peripapillary vascular changes secondary to radiation optic neuropathy (RON) using optical coherence tomography angiography (OCT-A) and to propose a clinical grading of RON based on OCT-A findings.

METHODS

Thirty-four patients affected by RON were consecutively included. Each patient underwent best corrected visual acuity measurement (ETDRS score) and OCT-A (Nidek RS-3000 Advance device, Nidek, Gamagori, Japan). The radial peripapillary capillary plexus (RPCP) and the entire peripapillary capillary bed (EPCB) were analysed. Quantitative analysis of the OCT-A images was performed using open-source available ImageJ software (National Institutes of Health, Bethesda, Maryland, USA). Qualitative analysis based on the proposed clinical grading (Grades 0-4) was also performed by two masked graders.

RESULTS

RON clinical (qualitative) classification based on RPCP correlated with the quantitative RPCP perfusion analysis (P=0.0001). RON clinical classification based on RPCP statistically correlated with ETDRS score (P=0.001). RON clinical classification based on EPCB also correlated with the quantitative EPCB perfusion analysis and ETDRS score (P=0.02 and P=0.01, respectively). Compared with the clinical classification based on EPCB, the qualitative classification based on RPCP reached a higher intergrader agreement (0.96 and 0.86, respectively).

CONCLUSION

OCT-A can be used to detect RPCP abnormalities and to clinically classify RON with a high interexaminer agreement. The proposed clinical classification is supported by the quantitative analysis based on the use of specific images elaboration techniques and correlates with visual acuity of the examined eyes.

An Update on Optical Coherence Tomography Angiography in Diabetic Retinopathy

Optical coherence tomography angiography (OCTA) is a novel non-invasive imaging modality for 3-dimensional visualization of retinal and optic nerve capillary networks. In this article, a comprehensive review of relevant original articles in the PubMed database was performed using the search terms "diabetic retinopathy," "diabetic macular edema," "diabetes mellitus," and "optical coherence tomography angiography." OCTA was found to detect microvascular changes early in diabetes mellitus, even before they become clinically evident. Morphological and qualitative assessment of vascular changes can help to determine the pathophysiological processes, activity, treatment, and follow-up of diabetic retinopathy (DR). Vessel density and foveal avascular zone are the most investigated quantified indices shown to be early predictors of DR, correlated to DR severity and visual function, and useful in predicting response to treatment. OCTA has shown to be a promising alternative to fluorescein angiography in the management of DR. Further studies are warranted to determine the role of OCTA in the routine clinical management of DR.

The Future of Imaging in Detecting Glaucoma Progression

Ocular imaging has been heavily incorporated into glaucoma management and provides important information that aids in the detection of disease progression. Longitudinal studies have shown that the circumpapillary retinal nerve fiber layer is an important parameter for glaucoma progression detection, whereas other studies have demonstrated that macular parameters, such as the ganglion cell inner plexiform layer and optic nerve head parameters, also are useful for progression detection. The introduction of novel technologies with faster scan speeds, wider scanning fields, higher resolution, and improved tissue penetration has enabled the precise quantification of additional key ocular structures, such as the individual retinal layers, optic nerve head, choroid, and lamina cribrosa. Furthermore, extracting functional information from scans such as blood flow rate and oxygen consumption provides new perspectives on the disease and its progression. These novel methods promise improved detection of glaucoma progression and better insight into the mechanisms of progression that will lead to better targeted treatment options to prevent visual damage and blindness.