Nonarteritic Anterior Ischemic Optic Neuropathy Eyes Research Articles

Features of Peripapillary Hyperreflective Ovoid Mass-Like Structures in Nonarteritic Anterior Ischemic Optic Neuropathy Patients and Normal Controls.

To determine the characteristics of peripapillary hyperreflective ovoid mass-like structures (PHOMS) in patients with nonarteritic anterior ischemic optic neuropathy (NAION) and in normal adults. A total of 406 included eyes were divided into four groups: acute NAION group, chronic NAION group, unaffected group, and normal eyes group. PHOMS were detected on optical coherence tomography slices from optical coherence tomography angiography scans centered on the optic nerve head (ONH). The differences in age, sex, and ONH parameters were investigated between eyes with PHOMS and eyes without PHOMS among groups. The prevalence of PHOMS in acute eyes (43.48%) and fellow eyes (28.20%) was significantly higher than that in normal eyes (11.76%) (acute vs. normal, P < 0.001; fellow vs. normal, P = 0.014). In the acute group, the PHOMS score of size was negatively correlated with age in acute eyes (r = -0.486, P = 0.03). The size of PHOMS was negatively correlated with age and cup/disc ratio and positively correlated with retinal nerve fiber layer thickness in the nasal and inferior sectors in the normal groups. No differences in age, sex, ONH parameters, or visual field defects were found between eyes with PHOMS and eyes without PHOMS. The prevalence of PHOMS increased significantly in acute nonoptic disc drusen (NODD)-NAION eyes and fellow eyes. PHOMS could also be found among normal adults. PHOMS may be a nonspecific sign secondary to ONH edema and axoplasmic stasis. The high prevalence of PHOMS in acute NODD-NAION eyes may indicate axoplasmic stasis secondary to tissue edema.

Assessment of macular and peripapillary choroidal thickness in non-arteritic anterior ischemic optic neuropathy: A meta-analysis

Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common optic neuropathy in adults aged ≥ 50 years. Transient non-perfusion or hypoperfusion of the optic nerve head circulation is believed to be the underlying cause of NAION. It has been suggested that peripapillary choroidal thickness (PCT) is altered after ischemic disorders of the optic nerve head, but the results have not always been consistent. To address this issue and provide evidence for the pathogenesis of NAION, we performed a meta-analysis to systematically evaluate macular choroidal thickness (MCT) and PCT in patients with NAION. A comprehensive literature search of PubMed, Embase, Cochrane Library, and Web of Science databases was performed until August 31, 2022. The main inclusion criterion was a case-control study in which MCT and PCT were measured using optical coherence tomography in patients with NAION. Mean difference (MD) and 95% confidence interval were calculated for continuous estimates. The Review Manager (V5.40) was used for the analysis. Nine studies comprising 663 eyes (283 NAION eyes and 380 healthy control eyes) were included (Newcastle-Ottawa Scale score ≥ 5). MCT and PCT were higher in eyes with chronic NAION (MD = 19.16, P = .04; MD = 35.36, P < .00001) and NAION fellow eyes (MD = 30.35, P = .0006; MD = 29.86, P = .04) than in healthy controls. No difference was noted in the MCT between eyes with acute NAION and healthy controls (MD = 2.99, P = .87). Increased MCT and PCT may be important anatomical and physiological features of the eyes in patients with NAION.

Peripapillary and macular microvasculature features of non-arteritic anterior ischemic optic neuropathy.

The hallmark of non-arteritic anterior ischemic optic neuropathy (NAION) is vascular compromise to the anterior optic nerve and thinning of the retinal nerve fiber layer (RNFL) and secondary degeneration of the retinal ganglion cell body or thinning of the ganglion cell complex (GCC). This study investigates optical coherence tomography (OCT) and OCT Angiography (OCTA) changes in chronic NAION and identifies imaging biomarkers that best predict disease. We performed a retrospective case-control study of 24 chronic NAION eyes (18 patients) and 70 control eyes (45 patients) to compare both whole-eye and regional OCT, OCTA, static perimetry measurements. OCT measurements were quantified automatically using commercial software, and OCTA was analyzed using custom MATLAB script with large vessel removal to measure 154 total parameters per eye. We confirmed that static perimetry mean deviation (MD) was significantly worse in chronic NAION (-13.53 ± 2.36) than control (-0.47 ± 0.72; P < 0.001) eyes, and NAION eyes had 31 μm thinner RNFL (control: 95.9 ± 25.8 μm; NAION: 64.5 ± 18.0, P < 0.001), and 21.8 μm thinner GCC compared with controls (control: 81.5 ± 4.4 μm; NAION: 59.7 ± 10.5, P < 0.001). Spearman correlation analysis of OCTA parameters reveal that vessel area density (VAD) and flux are highly correlated with visual field MD and OCT measurements. Hierarchical clustering two distinct groups (NAION and control), where standardized measurements of NAION eyes were generally lower than controls. Two-way mixed ANOVAs showed significant interaction between patient status (control and chronic NAION) and structure (optic disk and macula) for annulus VAD and flux values and mean RNFL and GCC thickness. Post-hoc tests showed this effect stems from lower peripapillary values in NAION compared to controls. Separate logistic regression models with LASSO regularization identified VAD and flux are one of the best OCTA parameters for predicting NAION. Ischemic insult to the optic disk is more severe likely from primary degeneration of the affected peripapillary region while macula is affected by secondary retrograde degeneration and loss of retinal ganglion cells. In addition to OCT measurements, peripapillary and macular vascular parameters such as VAD and flux are good predictors of optic nerve and retinal changes in NAION.

Characteristics of macrophage-like cells in acute nonarteritic anterior ischemic optic neuropathy and the normal fellow eyes on en face optical coherence tomography.

To quantitatively analyze macrophage-like cells (MLCs) at the vitreoretinal interface (VRI) in acute nonarteritic anterior ischemic optic neuropathy (NAION) using en face swept-source optical coherence tomography (OCT). Twenty-five acute NAION eyes and 25 normal fellow eyes from 25 patients were included in the study. MLCs were visualized in a 3 μm 6 mm×6 mm en face OCT slab above the VRI centered on the optic nerve head (ONH). After semiautomatic binarization and quantification, we evaluated the MLC density between the two groups. We also investigated the relationship between MLC density and other OCT parameters, including the increase in peripapillary retinal nerve fiber layer (RNFL) thickness and loss of vessel density (VD) in radical peripapillary capillary (RPC). The MLC density in the affected eye of the ONH was highly correlated with that in the fellow eye (r=0.612, p=0.001). The MLC density significantly increased in acute NAION eyes (NAION vs. normal, 11.97 ± 6.66 vs. 9.31 ± 6.10 cell/mm2, p=0.028). In sectorial analysis, the increase in MLCs was mainly in the superior regions (4.13 ± 7.49 vs. 0.94 ± 5.21 cell/mm2, p=0.001). The VD of RPC decreased significantly in the affected eyes (NAION vs. normal, 37.54 ± 5.25 vs. 40.56 ± 4.25, p=0.016), and the loss of RPC was predominantly in the superior sectors and the temporal sectors when compared to the inferior sectors and the nasal sectors, respectively (superior vs. inferior, -3.54 ± 6.71 vs. -0.37 ± 8.07, p=0.004; temporal vs. nasal, -2.69 ± 8.72 vs. -1.22 ± 6.06, p=0.005). The loss of RPC and the increase in MLC density were greater in affected sector corresponding to the visual field (VF) defect. MLCs located above the VRI increased significantly in acute NAION eyes, especially in subregions corresponding to VF defect, which provides clinical evidence supporting that the inflammatory response participates in the pathological process of NAION. The magnitude of the increase in MLCs corresponds to the RPC loss in the quadrant analysis.

Vision-Related Quality of Life and Association Between Retinal Parameters in Patients with Non-Arteritic Anterior Ischemic Optic Neuropathy.

PurposeTo evaluate visual-related quality of life (VR-QoL) and its association with optic nerve head microvasculature in individuals with nonarteritic anterior ischemic optic neuropathy (NAION) evaluated at the acute stage.MethodsIn this retrospective case-control study, 23 NAION eyes at the acute stage and 25 age and gender matched healthy eyes were included, respectively. All included eyes underwent a complete ophthalmic examination including optical coherence tomography (OCT) and OCT angiography (OCTA). The Chinese version of the National Eye Institute Visual Function Questionnaire-25 (CHI-NEI-VFQ-25) was applied to assess VR-QoL in individuals consecutively visited at an ophthalmic center. Descriptive and analytic statistics were employed.ResultsThere were no significant differences on age, gender, socioeconomic and education level (P > 0.05), but best-corrected visual acuity (BCVA) differences were reported between cases and controls (P < 0.05). Each peripapillary retinal nerve fiber layer (RNFL) thickness was higher but peripapillary vessel density (VD) and VR-QoL scores for all subscales were significantly lower in cases when compared with controls, respectively (P < 0.05). Particularly, pearson’s partial correlation analysis restricted to eyes with NAION revealed stronger correlations between peripapillary RNFL measurements, VD and VR-QoL.ConclusionNAION at the acute stage affects VR-QoL in Chinese individuals. Some peripapillary RNFL measurements and VD correlated with VR-QoL. Retinal anatomic and blood flow examinations and inventions in patients with NAION are necessary to facilitate VR-QoL and disease control.

Peripapillary Microvascular and Structural Parameters in Atrophic Nonarteritic Anterior Ischemic Optic Neuropathy and Their Unaffected Fellow Eyes.

This cross-sectional study aimed to evaluate the peripapillary vessel density (VD), peripapillary retinal nerve fiber layer (RNFL) thickness values of eyes with atrophic nonarteritic anterior ischemic optic neuropathy (NAION), and unaffected fellow eyes. Peripapillary VDs and RNFL thicknesses in the peripapillary region and 4 sectors (superior, inferior, nasal, and temporal) were evaluated using optical coherence tomography angiography among 19 atrophic NAION eyes, 19 unaffected fellow eyes, and 22 age-matched and sex-matched healthy controls. The NAION eyes had lower peripapillary VD and RNFL thickness values in all areas compared with both the fellow and the healthy control eyes ( P < 0.001 for all). The fellow eyes also demonstrated lower peripapillary VD values ( P = 0.02) despite similar RNFL thickness values ( P = 0.99) in the peripapillary region compared with the age-matched and sex-matched healthy controls. The peripapillary RNFL thickness values significantly correlated with peripapillary VD values in both NAION and fellow eyes. Diminished RNFL thickness and peripapillary VD values were observed in atrophic NAION eyes. In addition, a tendency for a lower peripapillary VD despite similar RNFL thickness values in the fellow eyes may indicate the potential vascular risk factors for NAION.

Peripapillary Choroidal Vascularity and Visual Correlates in Non-Arteritic Anterior Ischemic Optic Neuropathy Using Swept-Source Optical Coherence Tomography.

The peripapillary choroid shares a blood supply with and is directly apposed to the optic nerve, and therefore may contribute to the pathogenesis of non-arteritic anterior ischemic optic neuropathy (NAION). Prior studies evaluating peripapillary choroidal thickness (PCT) or choroidal vascularity index (CVI; the ratio of the perfused area to total choroid area) have produced mixed results. None investigated the relationship between PCT and CVI or demonstrated functional correlates. We hypothesized that greater PCT and lower CVI would correlate with visual function in patients presenting with NAION. Seventeen eyes with NAION (9 acute, 8 non-acute) and 6 unaffected "fellow" eyes in 13 patients, and 18 eyes in 18 age-matched control subjects were imaged using swept-source optical coherence tomography (SS-OCT) prospectively between 2017-2018. Mean PCT and CVI measurements were compared across groups and with respect to corresponding automated perimetric performance at the same visit. Analysis of variance showed significantly greater PCT (NAION: 278 ± 65 μm, Fellow: 221 ± 50 μm, Control: 158 ± 27 μm, p<0.001) and lower CVI (NAION: 0.35 ± 0.03, Fellow: 0.35 ± 0.04, Control: 0.38 ± 0.02, p<0.005) in patients with NAION compared to control subjects. Bonferroni-corrected pairwise comparisons showed greater PCT and lower CVI in NAION-affected eyes compared to control eyes (p values<0.008), and no significant differences in PCT or CVI between NAION and fellow eyes (p values>0.06). PCT was negatively correlated with CVI among unaffected fellow eyes (r=-0.8, p<0.05), but not among acute NAION eyes (r=-0.1, p>0.7), non-acute NAION eyes (r=0.1, p>0.7), or controls (r=-0.3, p>0.2). Nasal CVI was positively correlated with mean deviation scores in non-acute NAION (r=0.8, p<0.02), but not among fellow unaffected eyes (r=0.8, p>0.05) or acutely affected NAION eyes (r=-0.3, p>0.4). Mean and temporal PCT correlated with pattern standard deviation scores among unaffected fellow eyes (r=0.8, p<0.04; r=0.9, p<0.03), but not among acute NAION eyes (r=-0.2, p>0.5; r=-0.1, p>0.7) or non-acute NAION eyes (r=0.1, p>0.7; r=0.05, p>0.9). NAION and unaffected fellow eyes demonstrate increased choroidal thicknesses and reduced vascular density. Perimetric performance is directly associated with vascular density among non-acutely affected eyes with NAION. Ongoing work will provide further insights into these structure-function relationships with pathogenic and pathophysiologic relevance.

Retinal Nerve Fiber Layer-to-Disc Ratio Distinguishing Glaucoma from Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose: To evaluate the diagnostic value of retinal nerve fiber layer-to-disc ratio (RDR) compared to established parameters including retinal nerve fiber layer thickness (RNFLT), Bruch membrane opening-minimum rim width (BMO-MRW), and Bruch membrane opening-minimum rim area (BMO-MRA) for differentiating between open angle glaucoma (OAG) and nonarteritic anterior ischemic optic neuropathy (NAION).Methods: This retrospective study included 23 optic disc size-matched normal control eyes and 23 OAG and NAION eyes matched according to global RNFLT. The RDR, RNFLT, BMO-MRW, and BMO-MRA were analyzed; the diagnostic capabilities of these parameters were compared using the area under the receiver operating characteristic curve (AUC).Results: The global BMO-MRW and total BMO-MRA were lower in the OAG group than in the other two groups (all &lt;i&gt;p&lt;/i&gt; &lt; 0.001). RDR was greatest in the OAG group, followed by the healthy and NAION groups (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). Between the OAG and NAION groups, the AUCs for temporal inferior BMO-MRW, total BMO-MRA, and RDR were 0.987, 0.996, and 1.000, respectively; these were greater than the temporal inferior RNFLT (0.811; &lt;i&gt;p&lt;/i&gt; = 0.005, &lt;i&gt;p&lt;/i&gt; = 0.006, and &lt;i&gt;p&lt;/i&gt; = 0.006, respectively).Conclusions: RDR could be one of the useful parameters for differential diagnosis in OAG and NAION.

Dynamic volume-rendered optical coherence tomography pupillometry.

To assess intrapupillary space (IPS) changes in healthy subjects with regard to decreased iris motility in patients with pseudoexfoliation glaucoma (PEXG) or non-arteritic anterior ischaemic optic neuropathy (NAION) in a feasibility study in a clinical environment. Scotopic and photopic IPS measurements using three-dimensionally rendered swept-source optical coherence tomography (SS-OCT) data were obtained and compared for all subjects. Intrapupillary space (IPS) parameters were evaluated such as absolute volumetric differences, relative light response for volumetric ratios and pupillary ejection fraction (PEF) for functional contraction measurements. From a total of 122 IPS from 66 subjects, 106 IPS were eligible for comparison providing values for 72 normal, 30 PEXG and 4 NAION eyes. In healthy, PEXG and NAION subjects, scotopic overall mean IPS was 8.90, 3.45 and 4.16 mm3 , and photopic overall mean IPS was 0.87, 0.74 and 1.13 mm3 , respectively. Three-dimensional contractility showed a mean absolute difference of 8.03 mm3 for normals (defined as 100% contractility), 2.72 mm3 for PEXG (33.88% of normal) and 3.03 mm3 for NAION (38.50% of normal) with a relative light response ratio between scotopic and photopic volumes of 10.26 (100%), 4.69 (45.70%) and 3.67 (35.78%), respectively. Pupillary ejection fraction (PEF) showed a contractile pupillary emptying of 88.11% for normals, 76.92% for PEXG and 70.91% for NAION patients. This 3D pupillometry OCT assessment allows for quantitative measurements of pupil function, contractility and response to light. More specifically, PEF is presented as a potential (neuro)-pupillary outcome measure that could be useful in the monitoring of ophthalmic disorders that affect pupillary function.

Carotid disease and retinal optical coherence tomography angiography parameters in patients with non-arteritic anterior ischemic optic neuropathy.

In order to analyze the data and retinal microvasculature for non-arteritic anterior ischemic optic neuropathy (NAION), patients were referred to have carotid Doppler ultrasound(CDU) from 2016 to 2020. In this case-control observational study, 30 NAION patients were evaluated with CDU. Twenty-two NAION patients (at least 3months after the onset of symptoms) and 9 normal subjects underwent a complete ophthalmic examination including optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). NAION eyes and fellow eyes were further divided into two groups based on the presence of carotid stenosis (CS). NAION patients with CS were termed "CS-NAION"; and those without CS were termed "NCS-NAION." Measurements of radial peripapillary capillary vessel density (RPC VD), ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) thicknesses were compared among groups. Fourteen of 30 NAION patients referred to have carotid Doppler were positive for CS with each one of such referrals having less than 50% stenosis. RNLF, GCC and RPC VDs were reduced in NAION patients' eyes, when compared to controls and the fellow eyes. RPC VD was significantly lower in the temporal-superior (P = 0.037) and the superior-temporal (P = 0.012) sectors of the NCS-NAION patients than in the CS-NAION patients. No significant differences were found between CS-fellow eyes and NCS-fellow eyes in terms of RPC VDs, RNLF or GCC. Results of the study highlight the effect of the carotid artery stenosis on ocular perfusion pressure in the pathogenesis of NAION. More extensive studies are necessary.

Microvascular alterations detected by optical coherence tomography angiography in non-arteritic anterior ischaemic optic neuropathy: a meta-analysis.

To evaluate microvascular alterations with optical coherence tomography angiography (OCTA) in eyes with non-arteritic anterior ischaemic optic neuropathy (NAION) and the unaffected fellow eyes. Systematic review and meta-analysis. A comprehensive literature search was conducted in the PubMed and Embase databases through 6 September 2020, to identify the studies on NAION and the unaffected fellow eyes using OCTA. Eligible studies and data of interest were extracted and analysed by RevMan Software v. 5.4 and Stata Software v.14.0. The weighted mean differences and 95% confidence intervals were used to assess the strength of the association. Seventeen observational comparative studies, including 379 eyes with NAION, 175 unaffected contralateral eyes and 470 eyes of healthy controls, were identified. Compared to those of the healthy controls, the perfusion density (PD) of radial peripapillary capillary (RPC) and peripapillary superficial capillary plexus (ppSCP) of NAION were significantly lower. Moreover, the PD of the macular SCP (mSCP) in NAION was significantly reduced in the whole image, superior quadrant and temporal quadrant, while the macular deep capillary plexus (mDCP) showed a decreasing PD only within the whole image. Between unaffected fellow eyes and healthy eyes, significant differences of PD were demonstrated in the whole image and some peripapillary regions of the RPC and ppSCP. Our results suggested that compared to those of healthy controls, the eyes affected by NAION and unaffected fellow eyes demonstrated significant microvascular impairments in different regions. Between acute and non-acute NAION, macular OCTA parameters showed different characteristic patterns.

Evaluation of hemodynamic changes in nonarteritic anterior ischemic optic neuropathy using multimodality imaging.

Nonarteritic anterior ischemic optic neuropathy (NAION) patients experience hypo-perfusion in the short posterior ciliary arteries (SPCAs), however, the cause of hypo-perfusion is unclear. Real-time dynamic hemodynamic observations may provide clues into specific NAION pathogenic mechanisms. We aim to analyze hemodynamic changes occurring in NAION using multimodality imaging. Our specific focus is identifying pathogenic mechanisms underlying SPCA insufficiency in NAION. Three-dimensional arterial spin labeling (3D ASL) magnetic resonance imaging (MRI) and three-dimensional time-of-flight (3D-TOF) magnetic resonance angiography (MRA) were performed on 25 NAION patients (50 eyes) and 22 (44 eyes) normal cases were recruited. The diameter of the initial part of the ophthalmic artery and internal carotid artery siphon were measured using MRA. Blood vessel identification and blood flow (BF) were detected using 3D ASL MRI. We measured BF values of the optic nerve head (ONH) region of the retina/choroid complex, optic nerve (ON), temporal lobe, and occipital lobe. We studied 32 NAION affected eyes, 18 NAION uninvolved eyes, and 44 normal eyes. Diameter of the initial part of ophthalmic artery in the NAION affected eyes was significantly larger than the uninvolved eyes (P=0.026). Diameter of the NAION eyes was 1.33±0.19 mm [mean ± standard deviation (SD)], uninvolved eyes were 1.15±0.21 mm. At a photolabeling delay times (PLD) of 1,500 and 2,500 ms, BF of the ONH and ON in NAION affected eyes was significantly less than uninvolved and normal eyes (pONH <0.001 both at 1,500 and 2,500 ms, pON <0.001 and pON =0.001 at 1,500 and 2,500 ms, respectively). ONH of uninvolved eyes was also significantly less than normal eyes. Additionally, BF of the ONH region correlated with temporal lobe BF, with an R2=0.3231 and 0.2397 at 1,500 and 2,500 ms, respectively. BF of the ONH region also correlated with occipital lobe BF, with an R2=0.2534 and 0.4397 at 1,500 and 2,500 ms, respectively. ON and temporal lobe BF also correlated, with an R2=0.226 and 0.1504 at 1,500 and 2,500 ms, respectively. Abnormal hemodynamics of small cerebral vessels existed prior to the onset of NAION. A candidate mechanism underlying NAION appears to be transient insufficiency of blood supply and decompensation of ocular vascular regulation.

Microvascular and structural alterations in the optic nerve head of advanced primary open-angle glaucoma compared with atrophic non-arteritic anterior ischemic optic neuropathy.

This cross-sectional study compared the peripapillary vessel density (VD), peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters between eyes with atrophic non-arteritic anterior ischemic optic neuropathy (NAION) and eyes with advanced primary open-angle glaucoma (POAG) matched for visual field mean deviation. Peripapillary VDs and RNFL thicknesses in the peripapillary region, and 4 sectors (superior, inferior, nasal, and temporal), and scanning laser ophthalmoscopy parameters of the ONH were evaluated with optical coherence tomography angiography (OCTA) among 21 atrophic NAION cases, 26 advanced POAG cases, and 30 age- and sex-matched healthy controls. The POAG eyes had lower peripapillary VDs in all areas compared with the NAION eyes, which was most marked in the inferior and nasal sectors (p=0.005 for both). RNFL loss was similar between the 2 groups in all areas, except for a preserved thickness in the inferior sector in NAION eyes (p=0.01). Peripapillary VD demonstrated stronger correlations with global RNFL thickness in the peripapillary region in the NAION eyes compared with that of the POAG eyes (r=0.91 p<0.00001, r=0.42 p=0.03 respectively). In multivariate analysis, the peripapillary VD correlated with age and RNFL thickness in the POAG eyes while it correlated with SSI and RNFL thickness in the NAION eyes. A tendency for a lower peripapillary VD despite similar visual field mean deviation values may infer a more prominent role of the vascular regression in POAG compared with NAION.

Three-dimensional ophthalmic artery model reconstruction and assessment captured by computed tomographic angiography in non-arteritic anterior ischemic optic neuropathy patients.

BackgroundThe ophthalmic artery (OA) was first reconstructed using computer software. The structural differences of ophthalmic arteries in non-arteritic anterior ischemic optic neuropathy (NAION) and normal eyes, in addition to hemodynamic alterations, were assessed.MethodsThirty-one NAION eyes, 19 uninvolved eyes with NAION, and a control group of 26 healthy eyes were retrospectively included. Computed tomographic angiography data were recorded, and corresponding three-dimensional OA models were constructed. Initial OA and internal carotid artery (ICA) diameters and the angle between them were analyzed. Three different OA models were used to evaluate hemodynamic performance. The statistical relationships between the initial diameters of the OA and ICA and the angle between the OA and ICA were described.ResultsOA diameters in NAION eyes were significantly smaller than those in both uninvolved and healthy eyes (P<0.05). There was no significant difference between uninvolved and healthy eyes (P=0.31). The initial ICA diameter and the angle between the OA and ICA did not significantly differ among the three groups. In the three models, the blood flow velocity in the initial ophthalmic arteries of uninvolved eyes was higher than that in the NAION eyes. The mass flows of the right and left ophthalmic arteries, accounting for the ipsilateral ICA in the control model, were 0.57%. However, these values in uninvolved and NAION eyes were 1.36% and 0.25%, respectively.ConclusionsNAION is associated with a smaller initial OA diameter, which may be related to hypoperfusion. To our knowledge, this is the first pilot study to analyze hemodynamic alterations using OA models.

OCT angiography analysis in acute non-arteritic anterior ischemic optic neuropathy: The importance of segmentation.

In non-arteritic anterior ischemic optic neuropathy (NAION), optical coherence tomography angiography (OCTA) shows changes in peripapillary vascularization. However, the presence of an optic disc edema may induce artifacts that prevent visualizing the peripapillary network. The aim of this study was to evaluate the peripapillary vascularization in acute NAION using swept-source OCTA algorithms allowing segmenting only the retinal nerve fiber layer (RNFL). Retrospective analysis of 15 eyes with acute NAION of 15 patients. The optic nerve head was imaged using swept-source OCTA. Morphological and quantitative analyzes were performed. The capillary flux index (CFI), defined as the total weighted area of perfused vasculature per unit area, and the capillary perfusion density (CPD), defined as the total area of perfused microvasculature per unit area, were quantified. Each NAION eye was compared to the unaffected fellow eye using a Wilcoxon test for matched samples. After segmentation at the RNFL, the morphological analysis showed less vascular dropout and more vascular tortuosity than the analysis of a larger segmentation. The quantitative analysis showed that the mean CFI and the CFI in the four quadrants were significantly higher in NAION eyes compared to healthy eyes (p = 0.0002 and p < 0.01). The mean CPD and the CFD in the inferior quadrant were lower in NAION eyes (p = 0.03 and p = 0.0054, respectively). The RNFL segmentation allowed better visualizing the peripapillary network because the edema related darkening was reduced. The increased CFI suggests an autoregulatory phenomenon to compensate the ischemic process at the ciliary vasculature.

Comparison of Peripapillary Vessel Density of Acute Nonarteritic Anterior Ischemic Optic Neuropathy and Other Optic Neuropathies With Disc Swelling Using Optical Coherence Tomography Angiography: A Pilot Study.

The purpose of this study is to quantitatively compare the peripapillary vessel density (PPVD), measured with optical coherence tomography angiography (OCT-A), between acute nonarteritic anterior ischemic optic neuropathy (NAION) and other causes of disc swelling ("others"). In this prospective comparative case series, patients with unilateral disc swelling due to acute NAION (n = 7) and "others" (n = 7) underwent OCT-A scanning of the optic nerve head with a swept-source OCT (Triton DRI-OCT), in addition to functional assessment. OCT-A images were analyzed using an automated customized MATLAB program. Comparison was made between total and 6 sectoral PPVD (radial peripapillary capillary [RPC] and choroid layers) of affected and fellow eyes; and between the 2 groups' affected eyes. Five NAION patients had repeated assessments at 1, 3, and 6 months. Acute NAION eyes had a significantly lower total and superonasal PPVD (both layers) compared to fellow eyes. No such difference was observed in "others" group for the RPC layer. NAION eyes also had significantly lower total RPC PPVD than affected eyes in the "others" group. Over 6 months, NAION eyes had persistently lower RPC PPVD compared to fellow eyes but the reduced choroidal PPVD resolved by 1 month. The study demonstrated reduced superonasal and total RPC PPVD in acute NAION, which persisted over 6 months. Because there is currently no single diagnostic test for NAION, use of OCT-A images to analyze RPC PPVD may potentially help distinguish acute NAION from other causes of disc swelling by quantitatively demonstrating capillary dropout in the RPC layer.

Changes in the structure of retinal layers over time in non-arteritic anterior ischaemic optic neuropathy.

To examine structural changes in retinal layers over time in patients with non-arteritic anterior ischaemic optic neuropathy (NAION) and determine the layers that predict visual outcomes. The optical coherence tomography parameters in NAION eyes at <2 months, 2-5 months, and 6-18 months from the onset were compared to age-matched normal controls. Generalised estimating equation analysis was used to analyse the changes over time and regression analysis was performed to identify the layer that could predict visual field outcomes. Less than 2 months from the onset, the peripapillary retinal nerve fibre layer (RNFL) (p = 0.001) and macular outer nuclear layer (ONL) (p = 0.024) were significantly thicker in the NAION eyes than in the control eyes. The average peripapillary RNFL, macular RNFL, and ganglion cell layer and inner plexiform layer (GCIPL) showed reductions in thickness within 2-5 months (peripapillary RNFL: -19.8 μm/month, p < 0.001, macular RNFL: -14.5 μm/month, p < 0.001, GCIPL: -26.8 μm/month, p < 0.001). The change of thickness in temporal and superior peripapillary RNFL, GCIPL, inner nuclear layer (INL), and ONL by 2-5 months was associated with the final visual field results (p = 0.018, p < 0.001, p = 0.040, p = 0.020, and p = 0.002, respectively). The peripapillary RNFL swelling initially observed started to decrease within 2-5 months along with macular RNFL and GCIPL thinning. The rate of thickness changes in the peripapillary RNFL, GCIPL, INL, and ONL by 2-5 months was associated with visual field outcomes.

Patterns of Retinal Ganglion Cell Damage in Nonarteritic Anterior Ischemic Optic Neuropathy Assessed by Swept-Source Optical Coherence Tomography.

To evaluate the ability of macular ganglion cell and inner plexiform layer (mGCIPL) and retinal nerve fiber layer (RNFL) thickness measurements by long-wavelength swept-source optical coherence tomography (SS-OCT) to assess retinal ganglion cell (RGC) damage in nonarteritic anterior ischemic optic neuropathy (NAION). A retrospective study of 20 patients with unilateral NAION was performed. SS-OCT scanning of the macular and peripapillary areas was performed to measure the total and six-sector thicknesses of macular RNFL (mRNFL) and mGCIPL, as well as peripapillary RNFL (pRNFL) thicknesses in global and 12 clock-hour sectors. Further comparison of these thicknesses between NAION involved eyes and uninvolved counterparts was performed in 12 of the 20 patients at 4 visits. The thickness map and en face images generated by volume data of the posterior pole over a 12 × 9-mm area were used for RNFL analysis. Median time intervals between the visual symptom onset and first thinning occurrences of mGCIPL, mRNFL, and pRNFL were 17 days (95% Confidence Interval [CI] 14-18 days), 43 days (95% CI 32-48 days), and 70 days (95% CI 62-80 days), respectively. The thickness map indicated a significantly reduced pRNFL in the superior temporal sectors or temporal sectors after 9 weeks, and retinal damage corresponded to the superior hemisphere's mRNFL and mGCIPL. En face images showed that the RNFL thinning area gradually expanded along the retinal nerve fiber direction and progressed toward the optic nerve head. The patterns of RGC damage in the macular and peripapillary areas of NAION eyes can be revealed by SS-OCT. Objective measurement of SS-OCT is valuable in characterizing NAION.

Differentiation of Nonarteritic Anterior Ischemic Optic Neuropathy from Normal Tension Glaucoma by Comparison of the Lamina Cribrosa.

PurposeTo compare lamina cribrosa (LC) morphology between eyes with nonarteritic anterior ischemic optic neuropathy (NAION) and eyes with normal tension glaucoma (NTG) in the Korean population.MethodsThis retrospective study included 48 eyes with NAION, 48 eyes with NTG, and 48 healthy control eyes matched by age, intraocular pressure, axial length, and optic disc area. Eyes with NAION and NTG were also matched by retinal nerve fiber layer (RNFL) thickness in the affected sector. Optic nerve heads were scanned using enhanced depth imaging spectral-domain optical coherence tomography. LC depth (LCD) and the LC curvature index (LCCI) were measured at seven locations spaced equidistantly across the vertical optic disc diameter. LCD and the LCCI were compared in the three groups.ResultsRNFL thicknesses of the matched affected sectors did not differ between the NAION and NTG groups (P = 0.347). LCD and the LCCI were significantly larger in the NTG group than in the NAION and healthy control groups at all seven planes (P < 0.001 each), but were comparable in the NAION and healthy control groups. The LCCI was larger in the affected than in the unaffected sector of NTG eyes (P = 0.010) but did not differ in NAION eyes (P = 1.000). LCD did not differ between affected and unaffected sectors in either NAION (P = 0.600) or NTG (P = 0.098) eyes.ConclusionsLC morphology differed in eyes with NAION and NTG, despite a similar degree of RNFL damage. Evaluation of LC morphology may help to understand the distinctive pathophysiology of NAION and to differentiate NAION from NTG eyes.

Young Adults With Anterior Ischemic Optic Neuropathy: A Multicenter Optic Disc Drusen Study

Optic disc drusen (ODD), present in 2% of the general population, have occasionally been reported in patients with nonarteritic anterior ischemic optic neuropathy (NA-AION). The purpose of this study was to examine the prevalence of ODD in young patients with NA-AION. Retrospective, cross-sectional multicenter study. All patients with NA-AION 50 years old or younger, seen in neuro-ophthalmology clinics of the international ODDS (Optic Disc Drusen Studies) Consortium between April 1, 2017, and March 31, 2019, were identified. Patients were included if ODD were diagnosed by any method, or if ODD were excluded by enhanced-depth imaging optical coherence tomography (EDI-OCT) using ODDS Consortium guidelines. NA-AION eyes with ODD were termed "ODD-AION"; those without were termed "NODD-AION". A total of 65 patients (127 eyes) with NA-AION were included (mean 41 years old). Of the 74 eyes with NA-AION, 51% had ODD-AION, whereas 43% of fellow eyes without NA-AION had ODD (P= .36). No significant differences were found between ODD-AION and NODD-AION eyes in terms of Snellen best-corrected VA or perimetric mean deviation. According to EDI-OCT results, 28% of eyes with NODD-AION had peripapillary hyperreflective ovoid mass-like structures (PHOMS); 7% had hyperreflective lines, whereas 54% with ODD-AION had PHOMS; and 66% had hyperreflective lines (P= .006 and P < .001, respectively). Most of these young NA-AION patients had ODD. This indicates that ODD may be an independent risk factor for the development of NA-AION, at least in younger patients. This study suggests ODD-AION be recognized as a novel diagnosis.