Indocyanine green and fluorescein angiography in nonarteritic anterior ischemic optic neuropathy

Validation of retinal oximetry vessel selection using fluorescein angiography in patients with optic disc drusen

Retinal oximetry could provide insights into the pathophysiology of optic nerve disease, including optic disc drusen (ODD). Vessel selection for oximetry analysis is based on morphological characteristics of arterioles and venules and supported by an overlay of estimated blood oxygen saturations. The purpose of this cross-sectional study was to determine the validity of this vessel selection procedure by comparing it with vessel selection supported by video fluorescein angiography (FA). The study included 36 eyes of 36 patients with ODD who underwent retinal oximetry (Oxymap retinal oximeter T1) followed by FA (Heidelberg Spectralis). Two trained graders selected vessel segments in a pre-defined measurement area around the optic disc. One of these graders additionally performed the vessel segment selection with the support of FA images. When performed by the same grader, FA-supported and non-FA-supported vessel selection did not lead to significant differences in total vessel segment length, estimated oxygen saturations or vessel diameters (all p > 0.05). Inter-grader differences were found for arterial and venous segment lengths and arterial saturation (p < 0.05). A similar tendency was found for the arteriovenous saturation difference (p = 0.10). In conclusion, identifying vessel segments for retinal oximetry analysis based on vessel morphology and supported by a color-coded saturation overlay appears to be a valid method without the need for invasive angiography. A numerically small inter-grader variation may influence oximetry results. Further studies of retinal oximetry in ODD are warranted.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION): A Comprehensive Overview

Non-arteritic anterior ischemic optic neuropathy (NA-AION) represents one of the most important causes of blindness or severely impaired vision in middle-aged and elderly people. Unilateral optic disc edema and abrupt, painless vision loss are its defining features. It is commonly assumed that NA-AION is caused by an ischemic infarction of the optic nerve head, and, although the exact pathogenesis is still unknown, several risk factors and comorbidities associated with its development have been found. NA-AION occurs generally in patients older than 50 years who have small optic discs and vasculopathy risk factors. Even though numerous treatment options have been proposed, no available effective medical or surgical therapy or prophylactic measure for NA-AION currently exists. The purpose of present-day therapeutic strategies is therefore to identify and possibly control any underlying modifiable risk factors, aiming to prevent the development of new NA-AION episodes in the affected and fellow eye. A thorough assessment of NAION, including its history, epidemiology, etiology, pathophysiology, risk factors, associated comorbidities, clinical findings, diagnostic tests, treatment choices, prognosis, and future research, is the goal of this work.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION): A Comprehensive Overview

Non-arteritic anterior ischemic optic neuropathy (NA-AION) represents one of the most important causes of blindness or severely impaired vision in middle-aged and elderly people. Unilateral optic disc edema and abrupt, painless vision loss are its defining features. It is commonly assumed that NA-AION is caused by an ischemic infarction of the optic nerve head, and, although the exact pathogenesis is still unknown, several risk factors and comorbidities associated with its development have been found. NA-AION occurs generally in patients older than 50 years who have small optic discs and vasculopathy risk factors. Even though numerous treatment options have been proposed, no available effective medical or surgical therapy or prophylactic measure for NA-AION currently exists. The purpose of present-day therapeutic strategies is therefore to identify and possibly control any underlying modifiable risk factors, aiming to prevent the development of new NA-AION episodes in the affected and fellow eye. A thorough assessment of NAION, including its history, epidemiology, etiology, pathophysiology, risk factors, associated comorbidities, clinical findings, diagnostic tests, treatment choices, prognosis, and future research, is the goal of this work.

Evaluation of optical coherence tomography angiography changes in nonarteritic anterior ischemic optic neuropathy

Purpose

To study the long-term microvasculature changes at the macula and the optic disk in eyes with nonarteritic anterior ischemic optic neuropathy (NAION).

Methods

Patients with acute NAION of less than 6 weeks duration were included. Optical coherence tomography angiography (OCTA) of the macula and the optic disk was performed at baseline, 3 and 6 months and compared with the controls.

Results

The mean age of 15 patients was 52.25 (±9.06) years. The whole image superficial peripapillary density (42.49 ± 5.28) was significantly low when compared to that of control eyes (46.36 ± 2.09); similarly, radial peripapillary capillary density (49.35 ± 5.64) was also significantly reduced when compared to controls (53.45 ± 1.96, P < 0.05). These parameters showed significant progressive decrease at 3 and 6 months (P < 0.05). At the macula, both superficial (41.83 ± 3.64) and deep macular vasculature densities (47.30 ± 2.04) were significantly reduced when compared to control eyes (52.15 ± 4.84 and 55.13 ± 1.81, respectively). The vascular density at the macula remained stable at 3- and 6-months period.

Conclusion

The study shows that the microvasculature in case of NAION is significantly reduced both in peripapillary area and in macular area.

Vascular supply of the optic nerve head: implications for optic disc ischaemia

The vascular supply of the optic nerve head is complex and remains incompletely delineated. Over the past 50 years, various investigators have attempted to clarify the relative contributions of the choroid, the short posterior ciliary arteries and the central retinal artery to the vascular beds of the inner retinal, prelaminar, laminar and retrolaminar segments of the nerve head. Conflicting theories have evolved, in no small part due to differing techniques of study, involving both flow parameters and anatomical constructs. These have included studies, both in normal subjects and in those with optic nerve ischaemia, of histopathology, electron microscopic corrosion casting, orbital colour Doppler flow studies, fluorescein angiography, indocyanine green angiography, laser Doppler flow studies, laser speckle flowgraphy, microperfusion and labelling studies and optical coherence tomography angiography. The nature of the optic disc, peripapillary retina and choroid microvasculature has implications for the pathophysiology of ischaemic optic neuropathy.

Atypical chorioretinal lesions in Siberian Husky dogs with primary angle-closure glaucoma: a case series

BACKGROUND

A number of etiologies for different canine chorioretinal lesions have been proved or suggested but some fundic lesions remain unclear in terms of an etiologic diagnosis, treatment options and prognosis. The purpose of this case series is to describe atypical chorioretinal lesions observed in dogs with primary angle-closure glaucoma (PACG).

CASE PRESENTATION

Two spayed-female Siberian Huskies (3- and 4-year-old) and one Siberian Husky/Australian Shepherd mixed breed dog (11-month-old) that had multifocal depigmented retinal lesions and PACG were included.

PROCEDURES

Ophthalmic examination, gross, and histopathologic examination findings are described. One of the dogs underwent further clinical diagnostics. Advanced clinical diagnostics on the fellow, presumed to be non-glaucomatous eye of a dog revealed: pectinate ligament dysplasia by gonioscopy, retinal thinning in the depigmented area and wedge shaped retinal thinning with delayed choroidal vascular perfusion by optical coherence tomography, confocal scanning laser ophthalmoscopy, fluorescein and indocyanine green angiography. Quantifiable maze testing for the same eye revealed mild nyctalopia but the full-field electroretinogram showed no generalized decrease of retinal function. Genetic testing for mutations within the retinitis pigmentosa GTPase regulator gene causing X-linked progressive retinal atrophy in Siberian Huskies was negative. Histopathologic evaluations on enucleated eyes in two dogs confirmed goniodysgenesis, PACG with optic nerve head cupping, and diffuse inner retinal atrophy. In addition, segmental profound retinal atrophy, loss of retinal pigment epithelium, and adhesion of the retina to Bruch's membrane was observed and coincided with multifocal depigmented lesions noted on fundic examination.

CONCLUSIONS

To our knowledge, this is the first case series with clinical and histopathologic data of chorioretinal lesions, most likely caused by severely impaired choroidal perfusion. Further studies are warranted to elucidate the etiology and pathophysiology, including its possible association with PACG.

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

PURPOSE

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.

DESIGN

Systematic review and meta-analysis.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

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

BACKGROUND

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").

METHODS

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.

RESULTS

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.

CONCLUSION

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.

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

PURPOSE

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.

METHODS

In this case-control observational study, 30 NAION patients were evaluated with CDU. Twenty-two NAION patients (at least 3 months 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.

RESULTS

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.

CONCLUSION

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.

Comparison of Optic Nerve Head Microvasculature Between Normal-Tension Glaucoma and Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose

To compare the microvasculature of the optic nerve head (ONH) and peripapillary tissues in eyes with normal-tension glaucoma (NTG) and nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).

Methods

Thirty-eight eyes with treatment-naïve NTG, 38 eyes with NAION matched for retinal nerve fiber layer (RNFL) thickness in each superior and inferior quadrant, and 38 healthy eyes matched by age were included. ONH and peripapillary retinal microvasculature was evaluated in en face images obtained using OCTA. Vessel density (VD) was calculated as the percent area occupied by vessels in the measured region in each layer segmented into the prelaminar tissue (PLT), lamina cribrosa (LC), and peripapillary retina (PR).

Results

VDs in the PLT and LC were lower in NTG eyes than in both NAION and healthy eyes (P ≤ 0.008), and did not differ between the NAION and healthy eyes. VDs in the PR did not differ between the NTG and NAION eyes. In intersectoral comparisons, VDs in the PLT (P = 0.030) and LC (P = 0.028) were lower in the affected than in the unaffected sector of eyes with NTG, but the differences did not occur in eyes with NAION. VD in the PR was lower in the affected than in the unaffected sector in both NTG and NAION eyes (both P < 0.001).

Conclusions

Despite similar degrees of RNFL loss and VD decreases in the PR, VDs in the ONH differed between eyes with NTG and NAION, indicating different mechanisms of vascular impairment and ONH damage in each condition.

Biomarkers of lesion severity in a rodent model of nonarteritic anterior ischemic optic neuropathy (rNAION)

The rodent model of nonarteritic anterior ischemic optic neuropathy (rNAION) is similar in many of its pathophysiological responses to clinical NAION. Like human NAION, there is significant variability in the severity of the lesion produced, and little is known of the parameters associated with rNAION induction severity or if pre- or early post-induction biomarkers can be identified that enable prediction of lesion severity and ultimate loss of retinal ganglion cells (RGCs). Adult male Sprague-Dawley outbred rats were evaluated for various parameters including physiological characteristics (heart rate, respiratory rate, temperature, hematocrit [Hct]), optic nerve head (ONH) appearance, pre- and post-induction mean diameter, and intravenous fluorescein and indocyanine green angiographic patterns of vascular leakage at 5 hours post-induction, performed using a spectral domain-optical coherence tomography (SD-OCT) instrument. Early changes were correlated with ultimate RGC loss by Brn3a (+) immunohistology. RGC loss also was correlated with the relative level of laser exposure. The severity of ONH edema 2d, but not 5hr, post induction was most closely associated with the degree of RGC loss, revealing a threshold effect, and consistent with a compartment syndrome where a minimum level of capillary compression within a tight space is responsible for damage. RGC loss increased dramatically as the degree of laser exposure increased. Neither physiological parameters nor the degree of capillary leakage 5hr post induction were informative as to the ultimate degree of RGC loss. Similar to human NAION, the rNAION model exhibits marked variability in lesion severity. Unlike clinical NAION, pre-induction ONH diameter likely does not contribute to ultimate lesion severity; however, cross-sectional ONH edema can be used as a biomarker 2d post-induction to determine randomization of subjects prior to inclusion in specific neuroprotection or neuroregeneration studies.

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.

Peripapillary and Macular Flow Changes in Nonarteritic Anterior Ischemic Optic Neuropathy (NAION) by Optical Coherence Tomography Angiography (OCT-A)

Background

To analyze the blood flow changes of radial peripapillary capillaries (RPCs) and macula with time procession in patients with nonarteritic anterior ischemic optic neuropathy (NAION) by optical coherence tomography angiography (OCT-A).

Methods

A total of 21 affected eyes and 19 unaffected eyes from 21 NAION patients were included. Assessments of BCVA, CFP, SD-OCT, and OCT-A were performed on NAION patients at enrollment and at 1-2 weeks, 1-2 months, and 3–6 months after enrollment. Measures of the thickness of the peripapillary retinal nerve fiber layer (wRNFL) and macular ganglion cell complex (wGCC) of the whole image in SD-OCT, vessel density of the RPC (wRPC) and superficial and deep vascular complexes (wSVD, wDVD) in the whole image of OCT-A, and their superior- and inferior-hemi values (s/iRNFL, s/iGCC, s/iRPC, and s/iSVD) were assessed.

Results

Compared to unaffected control eyes, wRPC (p ≤ 0.001) was significantly lower in affected eyes at baseline, and there was no significant difference in wSVD (p > 0.05). The wRPC and wSVD values of affected eyes were significantly decreased at follow-up time points of 1–2 and 3–6 months compared to baseline (p=0.001, p ≤ 0.001; p ≤ 0.001, p ≤ 0.001). The sRPC values were significantly lower than iRPC at 1-2/3–6 months (p=0.016, p=0.013), and sSVD values were lower than iSVD at 1-2 months (p=0.010). Statistically significant correlations were found between wRPC and wRNFL values at 3–6 months (r = 0.626, p=0.022), between wSVD and wGCC at 1-2 weeks and 1-2 months (r = 0.570, r = 0.436; p=0.007, p=0.048).

Conclusion

OCT-A revealed a sectorial reduction in vessel density in the RPC and macula with the disease progression of NAION from acute to atrophic stages, a classification associated with structural deficits.

Optical Coherence Tomography Angiography Assessment of the Peripapillary Vessel Density and Structure in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy: A Meta-Analysis

Background

This meta-analysis is aimed at assessing the peripapillary vessel density (VD) and structural outcomes using optical coherence tomography angiography (OCTA) in patients with nonarteritic anterior ischemic optic neuropathy (NAION).

Methods

A comprehensive search of PubMed, Embase, Cochrane Library, and Web of Science databases for literature comparing VD and structural outcomes in patients with NAION and controls was performed. Mean differences (MDs) and its 95% confidence interval (CI) were calculated for continuous estimates. Review Manager (V5.30) was used for analysis.

Results

Fourteen published studies met the requirement. The radial peripapillary capillary (RPC) whole enface VD measured by OCTA was significantly lower in patients with NAION compared to that of the controls (MD = −10.51, P < 0.00001). The RPC inside disc VD was significantly decreased in the NAION group than that in the control group (MD = −8.47, P < 0.00001). For RPC peripapillary VD, there was a statistically significant difference between patients with NAION and the controls (MD = −12.48, P < 0.00001). The peripapillary retinal nerve fibre layer (p-RNFL) thickness was significantly lower in patients with NAION in comparison to the controls (MD = −22.18, P = 0.004). The ganglion cell complex (GCC) thickness in the macular zone of NAION patients was remarkably reduced compared to that in the controls (MD = −17.18, P = 0.0002).

Conclusions

The findings suggested that the peripapillary VD and RNFL thickness were attenuated, and the macular GCC thickness was reduced in patients with NAION. OCTA, in the future, may facilitate the diagnosis and monitoring of patients with NAION.

Choroidal Thickness in Acute Non-arteritic Anterior Ischemic Optic Neuropathy

Purpose

To compare the choroidal thickness in eyes with acute non-arteritic anterior ischemic optic neuropathy (NAION) with healthy contralateral eye and normal controls.

Methods

Thirty-eight eyes with NAION, thirty-eight unaffected fellow eyes, and seventy-four eyes from 37 healthy, age- and sex-matched subjects were included in this prospective comparative case-control study. Choroidal thickness was measured by enhanced depth imaging (EDI) of spectral domain optical coherence tomography (SD-OCT). Peripapillary choroidal thickness (PCT) was measured at 1000 and 1500 μm from Bruch's membrane opening (BMO). Subfoveal choroidal thickness (SFCT) was measured in central subfoveal area, and 500 microns apart in temporal and nasal sides. Choroidal thickness among NAION eyes, uninvolved fellow eyes, and control eyes were compared.

Results

The mean of PCT at 1000 μm was significantly thicker in NAION and fellow eyes compared to control eyes (169.7 ± 47, 154.4 ± 42.1, and 127.7 ± 49.9 μm, respectively, P< 0.001 and P = 0.42). The mean PCT at 1500 μm was also significantly thicker in NAION and fellow eyes compared to control eyes (178.6 ± 52.8, 162.6 ± 46.1, and 135.1 ± 59 μm, respectively, P = 0.007 and P = 0.048). The mean PCT at 1000 and 1500 μm was significantly greater in NAION compared to fellow eyes (P = 0.027 and P = 0.035, respectively). The mean of SFCT was significantly thicker in NAION compared to control eyes (P = 0.032); however, there was no significant difference between uninvolved fellow and control eyes (P = 0.248).

Conclusion

Thicker choroidal thickness in acute NAION and uninvolved fellow eyes compared to normal eyes suggests a primary choroidal role in NAION pathophysiology.

Assessment of peripapillary vessel density in acute non-arteritic anterior ischemic optic neuropathy

PURPOSE

To assess the peripapillary perfusion in eyes with acute non-arteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).

METHODS

Twenty-five patients with unilateral acute NAION were included in this observational cross-sectional study. They were divided into two groups: group I (25 eyes) included eyes with acute NAION, and group II (25 eyes) included fellow normal eyes. Diagnosis of NAION was based on clinical examination and fluorescein angiography. OCTA (AngioVue, Optovue) was used to evaluate the optic nerve head perfusion and measure the peripapillary vessel density in all eyes included in the study.

RESULTS

Fourteen male and 11 female patients with a mean age of 60.2 ± 3.5 years were included in this study. The mean duration of presentation was 4.3 ± 0.6 days. Mean BCVA was 0.13 ± 0.06 and 0.69 ± 0.18 in eyes with NAION and normal eyes, respectively (p < 0.001). The peripapillary vessel was significantly decreased in all eyes with NAION compared with normal ones (p < 0.001). Two morphological changes were noted in eyes with NAION: vascular dropout related to area of disc edema in 25 eyes (100% of eyes) and vascular dilatation with tortuosity in 17 eyes (68%).

CONCLUSION

Eyes with NAION have decreased peripapillary vessel density with peripapillary vascular dilatation and tortuosity as assessed by OCTA.

Exploring choroidal angioarchitecture in health and disease using choroidal vascularity index

The choroid is one of the most vascularized structures of the human body and plays an irreplaceable role in nourishing photoreceptors. As such, choroidal dysfunction is implicated in a multitude of ocular diseases. Studying the choroid can lead to a better understanding of disease pathogenesis, progression and discovery of novel management strategies. However, current research has produced inconsistent findings, partly due to the physical inaccessibility of the choroid and the lack of reliable biomarkers. With the advancements in optical coherence tomography technology, our group has developed a novel quantitative imaging biomarker known as the choroidal vascularity index (CVI), defined as the ratio of vascular area to the total choroidal area. CVI is a potential tool in establishing early diagnoses, monitoring disease progression and prognosticating patients. CVI has been reported in existing literature as a robust marker in numerous retinal and choroidal diseases. In this review, we will discuss the current role of CVI with reference to existing literature, and make postulations about its potential and future applications.

Choroidal Vascular Changes in Arteritic and Nonarteritic Anterior Ischemic Optic Neuropathy

PURPOSE

To compare choroidal vascularity index (CVI) in patients with arteritic anterior ischemic optic neuropathy (A-AION), nonarteritic anterior ischemic optic neuropathy (NA-AION), and control subjects.

DESIGN

Retrospective cross-sectional study.

METHODS

This study was conducted at the Ophthalmology Unit of the S.Orsola-Malpighi University Hospital (Bologna, Italy). Macular and optic nerve head optical coherence tomography (OCT) scans of 20 patients with A-AION secondary to giant cell arteritis (biopsy-proven), 20 patients with NA-AION, and 20 control subjects were acquired with Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany). Images were binarized using ImageJ software, and total choroid area (TCA), luminal area (LA), and stromal area (SA) were segmented. The main outcome measure was CVI, defined as the ratio of LA to TCA.

RESULTS

Patients with A-AION showed a significantly lower macular and peripapillary CVI compared to both patients with NA-AION (respectively, 67.17 ± 2.35 vs 69.66 ± 4.18, P = .048; 63.51 ± 3.29 vs 67.67 ± 3.07, P < .001) and control subjects (respectively, 67.17 ± 2.35 vs 70.00 ± 2.95, P = .021; 63.51 ± 3.29 vs 68.69 ± 3.19, P = .002). Conversely, no significant difference in macular and peripapillary CVI was found between patients with NA-AION and controls (respectively, P = .942 and P = .570). After adjustment for age, the difference of peripapillary CVI among groups remained statistically significant (P < .001), while the difference in macular CVI did not (P = .060).

CONCLUSIONS

Macular and peripapillary CVI are reduced in patients with A-AION. These parameters may be useful to quantitatively evaluate choroidal vascular dysfunction in A-AION, serving as a new additional diagnostic tool to distinguish A-AION from NA-AION.

Choroidal Vascularity in Non-arteritic Anterior Ischaemic Optic Neuropathy

This study evaluates the peripapillary choroidal vascularity in eyes with non-arteritic anterior ischaemic optic neuropathy (NAION) and compares it with the vascularity of healthy fellow eyes and age-matched subjects. The peripapillary choroidal vascularity index (CVI), a new tool of measurement, was calculated using horizontal swept-source optical coherence tomography scans. CVI was calculated using a previously validated automated algorithm. CVI in NAION and fellow eyes of NAION patients were compared with age-matched eyes of healthy individuals using Kruskal-Wallis test. A total of 20 eyes of 20 patients with acute unilateral NAION with healthy fellow eyes (20 eyes) and 40 eyes of 40 healthy patients were included in the study. The average age of patients with NAION was 56 ± 8 and 55 ± 7 years in age-matched healthy controls. NAION eyes had a significantly lower CVI than age-matched controls in both nasal and temporal areas. NAION nasal CVI was 0.47 ± 0.47 compared to 0.62 ± 0.04 in controls (p < 0.001). NAION temporal CVI was 0.45 ± 0.48 compared to 0.58 ± 0.04 in controls (p < 0.001). Temporal CVI was 0.45 ± 0.48 in NAION eyes and was significantly lower than counterpart healthy fellow eyes 0.48 ± 0.02 (p = 0.007). In conclusion, NAION eyes have significantly reduced vascularity in the peripapillary area. CVI is lower in the nasal and temporal of the optic disc compared to healthy individuals. This may suggest those with smaller CVI are more prone to ischaemia from reduced vascularity resulting in NAION.

Spectral-Domain Optical Coherence Tomography of the Vitreopapillary Interface in Acute Nonarteritic Anterior Ischemic Optic Neuropathy

PURPOSE

To use spectral-domain optical coherence tomography (SD-OCT) to assess whether epipapillary vitreous traction from evolving posterior vitreous detachment (PVD) is mechanistically involved in the pathogenesis of nonarteritic anterior ischemic optic neuropathy (NAION).

DESIGN

Retrospective cohort study.

METHODS

Setting: Single academic center. Patient or Study Population: Eighty eyes in 74 subjects presenting within 2 weeks of symptom onset of NAION. Intervention or Observation Procedures: SD-OCT imaging of the optic nerve head, macula, and peripapillary retinal nerve fiber layer (pRNFL) were reviewed for PVD and vitreopapillary traction (VPT).

MAIN OUTCOME MEASURES

Prevalence and incidence of PVD and VPT, logMAR best-corrected visual acuity (BCVA), mean deviation (MD) on automated perimetry, and pRNFL thickness at presentation and final follow-up.

RESULTS

The co-prevalence of PVD at the time of acute presentation for NAION was 30% (n = 24/80). This was similar to the prevalence of PVD in contralateral uninvolved eyes (34.5%, n = 19/55). In 8 NAION eyes, PVD had been documented prior to the onset of NAION. No eyes had SD-OCT evidence of VPT on presentation or final follow-up. Only 5 eyes developed a PVD following the development of NAION, and this typically occurred months after resolution of optic disc edema. When comparing eyes with PVD and without PVD, there was no significant difference in BCVA, MD, and pRNFL thickness at baseline, final follow-up, or the change from baseline to final follow-up (all P > .10).

CONCLUSIONS

VPT was not mechanistically related to the development of classic NAION. Preexisting PVD did not preclude the future development of NAION. The co-prevalence of PVD with acute NAION had no impact on final visual outcome.

Optical Coherence Tomography Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy

BACKGROUND

Optical coherence tomography angiography (OCTA) has demonstrated good utility in qualitative analysis of retinal and choroidal vasculature and therefore may be relevant in the diagnostic and treatment efforts surrounding nonarteritic anterior ischemic optic neuropathy (NAION).

METHODS

Retrospective, cross-sectional study of 10 eyes of 9 patients with a previous or new diagnosis of NAION that received imaging with OCTA between November 2015 and February 2016. Two independent readers qualitatively analyzed the retinal peripapillary capillaries (RPC) and peripapillary choriocapillaris (PCC) for flow impairment. Findings were compared with automated visual field and structural optical coherence tomography (OCT) studies.

RESULTS

Flow impairment seen on OCTA in the RPC corresponded to structural OCT deficits of the retinal nerve fiber layer (RNFL) and ganglion cell layer complex (GCC) in 80% and 100% of eyes, respectively, and to automated visual field deficits in 90% of eyes. Flow impairment seen on OCTA in the PCC corresponded to structural OCT deficits of the RNFL and GCC in 70% and 80% of eyes, respectively, and to visual field deficits in 60%-80% of eyes.

CONCLUSIONS

OCTA can noninvasively visualize microvascular flow impairment in patients with NAION.

Hypothesis: Watershed zones in the human eye are a key for understanding glaucomatous retinal damage

The pathogenesis of glaucoma is complex which has led to numerous hypothesizes concerning the important factors creating this specific type of inner retinal degeneration namely apoptosis of retinal ganglion cells. We favor a primary vascular etiology and provide evidence that the pathogenesis of glaucoma should not be confined to changes exclusively at the optic nerve head but must include changes occurring in the peripheral retina with particular emphasis on the watershed zones of both the retina and choroid. This focus may help to sharpen ones awareness for early glaucoma treatment particularly in patients with minimal findings suggestive of glaucoma.

Microvasculature dropout detected by the optical coherence tomography angiography in nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

To investigate microcirculation characteristics of peripapillary superficial retina and optic disc in eyes with nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).

METHODS

Forty-one eyes of 30 NAION patients and 30 eyes of 30 normal subjects were evaluated with OCTA (AngioVue, Optovue). The whole vessel density, inside disc vessel density, peripapillary vessel density, and vessel densities based on the sectorial division in the nerve head mode peripapillary superficial retina and RPC mode optic disc were measured respectively.

RESULTS

In the NAION group, vessel densities in both the peripapillary superficial retina and optic disc were significant reduced (P < 0.01), as compared with the control group. The whole vessel density of the optic disc in chronic NAION group were significantly lower than that in acute NAION group (P < 0.01). The whole and temporal vessel density of the peripapillary superficial retina was significantly correlated with log MAR VA (r = -0.381 and r = -0.337, both P < 0.05). Vessel densities in both the peripapillary superficial retina and optic disc were reduced (P < 0.05) in unilateral involved eyes, as compared to the unaffected fellow eyes, except for the inside disc (P = 0.270) and SN (P = 0.054) vessel density in the optic disc, while there was no difference in the fellow eyes compared to the normal eyes.

CONCLUSION

In NAION patients, a dropout of microvasculature in peripapillary superficial retina and optic disc could be detected by OCTA directly. OCTA might become a useful tool for detection and monitoring of NAION. Lasers Surg. Med. 50:194-201, 2018. © 2017 Wiley Periodicals, Inc.

Optical coherence tomography angiography in acute arteritic and non-arteritic anterior ischemic optic neuropathy

PURPOSE

The purpose of our study was to describe the feature of acute non-arteritic or arteritic anterior ischemic optic neuropathy (NA-AION and A-AION) using optical coherence tomography angiography (OCT-A) and to compare it with fluorescein angiography (FA) and indocyanine green angiography (ICGA).

METHODS

In this retrospective, observational case-control study four NA-AION patients and one A-AION patient were examined by FA, ICGA and OCT-A within 2 weeks from disease presentation. The characteristics of the images were analyzed. Optic nerve head (ONH) and radial peripapillary capillaries (RPC) vessel densities (VDs) were compared between NA-AION and controls.

RESULTS

In two of four NA-AION cases and in the A-AION patient, OCT-A clearly identified the boundary of the ischemic area at the level of the optic nerve head, which was comparable to optic disc filling defects detected by FA. In the other two NA-AION cases, a generalized leakage from the disc was visible with FA, yet OCT-A still demonstrated sectorial peripapillary capillary network reduction. Both ONH and RPC VDs were reduced in NA-AION patients, when compared to controls.

CONCLUSIONS

OCT-A was able to identify microvascular defects and VD reduction in cases of acute optic disc edema due to NA-AION and A-AION. OCT-A provides additional information in ischemic conditions of the optic nerve head.

Diabetic papillopathy treated with intravitreal ranibizumab

In this report, we present a case of diabetic papillopathy that resolved after a single dose of intravitreal ranibizumab injection. A 50-year-old male presented with painless visual loss in his right eye. His visual acuity was 1/10 in the right eye and 10/10 in the left eye. Anterior segment examination of both eyes was unremarkable. Posterior segment of the right eye showed nonproliferative diabetic retinopathy with a swollen optic disc. Fluorescein angiography and optical coherence tomography were performed. There was dye leakage from the right optic disc. Optical coherence tomography revealed a significant increase in retinal nerve fiber layer thickness. Magnetic resonance imaging of the brain and orbit were normal. The patient received a single intravitreal ranibizumab (0.5 mg) injection. Two weeks after the injection, there was a marked regression of the disc swelling. Three months after the injection the optic disc was pallor and visual acuity was 6/10.

Evaluation of Choroidal Thickness in Non-arteritic Anterior Ischaemic Optic Neuropathy at the Acute and Chronic Stages

The objective of this study was to evaluate the measurements of choroidal thickness (CT) in patients with non-arteritic anterior ischaemic optic neuropathy (NAION) at the acute and chronic stages. This case-control study compares three groups: Group 1 included 23 eyes of 23 patients with chronic NAION, Group 2 consisted of 24 eyes of 24 patients with acute NAION, and Group 3 included 24 eyes of 24 age-matched control subjects. The average CTs for Group 1, Group 2, and Group 3 were 261.24 ± 50.04, 280.05 ± 74.94, and 254.74 ± 50.11 µm, respectively. For all measurements, no statistical significance was found between the groups (p = 0.319, 0.357, 0.680, and 0.178 for the CTs as average, foveal, superior, and inferior, respectively). Similarly, there was no difference between the CT measurements of the affected and unaffected eyes in Group 1 and Group 2 (p = 0.571, 0.741 for average, respectively). The amount of time after the onset of the disease ranged from 6.0 to 48 months (23.86 ± 16.70 months) in Group 1 and from 1 to 30 days (7.45 ± 8.86 days) in Group 2. There was no correlation between the CTs and follow-up times in Group 1 (p = 0.768 for average) and no association between the CTs and the thicknesses of the retinal nerve fibre layers in Group 2 (p = 0.453 for average). CT is not directly influenced by NAION at either the acute or the chronic stage of the disease. These results may also demonstrate that the changes of CT do not increase the risk of experiencing a NAION attack.

Analysis of Fundus Photography and Fluorescein Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy and Optic Neuritis

Purpose

We evaluated fundus and fluorescein angiography (FAG) findings and characteristics that can help distinguish nonarteritic anterior ischemic optic neuropathy (NAION) from optic neuritis (ON).

Methods

Twenty-three NAION patients and 17 ON with disc swelling patients were enrolled in this study. We performed fundus photography and FAG. The disc-swelling pattern, hyperemia grade, presence of splinter hemorrhages, cotton-wool spots, artery/vein ratio and degree of focal telangiectasia were investigated. The FAG findings for each patient were compared with respect to the following features: the pattern of disc leakage in the early phase, arteriovenous (artery/vein) transit time (second), and the presence and pattern of the filling delay.

Results

Cotton-wool spots, focal telangiectasia, and venous congestion were more common in the affected eyes of NAION patients. Upon FAG, 76.5% of the patients in the ON group exhibited normal choroidal circulation. However, 56.5% of patients in the NAION group demonstrated abnormal filling defects, such as peripapillary, generalized, or watershed zone filling delays.

Conclusions

Fundus findings, including cotton-wool spots, focal telangiectasia, and venous congestion in the affected eye, may be clues that can be used to diagnose NAION. In addition, choroidal insufficiencies on FAG could be also helpful in differentiating NAION from ON.

Is there treatment for nonarteritic anterior ischemic optic neuropathy

PURPOSE OF REVIEW

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common cause of an acute optic neuropathy over the age 50 with an annual incidence of 2-10/100 000. Most patients are left with a permanent decrease in visual acuity and visual field loss. No approved treatment has conclusively reversed the process or prevented a second event that typically involves the previously unaffected eye. Many medical and surgical treatments have been proposed with conflicting results. The goal of this review is to present current data in order to permit clinicians and patients to make an educated decision about treatment.

RECENT FINDINGS

Recently, there has been a flurry of case reports, small clinical trials and testing in animal models of NAION for various treatments for NAION and this review attempts to present the data concisely with the authors' opinions about the reliability of the data.

SUMMARY

To date, there is no class I evidence of benefit for the treatment of NAION; however, the aphorism attributed to Carl Sagan, PhD aptly applies: 'Absence of evidence is not evidence of absence'.

Macular choroidal thickness in non-arteritic ischemic optic neuropathy

OBJECTIVE

To analyse macular choroidal thickness (MCT) in non-arteritic ischaemic optic neuropathy (NAION).

MATERIALS AND METHODS

An analysis was made on 22 patients diagnosed with NAION (22 eyes) and 42 healthy controls (42 eyes) using enhanced-depth imaging of spectral-domain optical coherence tomography. A horizontal raster scan centred on the fovea was obtained per eye 3 months after the onset of NAION. Three measurements of MCT were obtained from the posterior edge of the retinal pigment epithelium to the choroid-sclera junction at 500μm intervals. Statistical analysis was used to compare the mean MCT and to correlate MCT with other ocular and systemic parameters.

RESULTS

Except for refractive error (P=.01), there were no statistically significant differences between both groups in axial length (P=.53), age (P=.88) and other epidemiological and ocular parameters. Mean MCT in NAION eyes and control group was 236.21±63.29μm and 269.13±52.28, respectively. Mean MCT was significantly thinner in NAION eyes than in healthy eyes (P=.03). Thinner MCT, adjusted for refractive error, was associated with the diagnosis of NAION (P=.04).

CONCLUSIONS

Eyes affected by NAION showed significantly thinner MCT compared with healthy control eyes after adjusting for refractive error.

Diabetic papillopathy with macular edema treated with intravitreal bevacizumab

A 46-year-old diabetic male presented with acute painless visual loss in his left eye (OS). Visual acuity was 6/36 OS with an unremarkable anterior segment examination (OU). Posterior segment showed a swollen left optic disc with large diffuse macular edema and moderate nonproliferative diabetic retinopathy (NPDR). The right eye fundus showed only mild NPDR. Optical coherence tomography and fundus fluorescein angiography were performed which revealed left macular edema and a hyperfluorescent left optic disc. Computerized tomography scan orbit and brain was normal. The patient received an intravitreal bevacizumab injection OS followed by focal laser photocoagulation 1 month later. His optic disc swelling and the macular edema subsided rapidly after the injection and his visual acuity improved to 6/6 with disc pallor.

Anterior ischemic optic neuropathy associated with udenafil

We report a case of anterior ischemic optic neuropathy associated with udenafil. A 54-year-old male presented with an acute onset visual field defect of the right eye after udenafil use. Examination revealed a relative afferent pupillary defect and a swollen disc. Automated visual fields revealed an enlarged blind spot and a narrowed visual field. Fluorescein angiography revealed both an inferior choroidal filling delay and an inferior sector filling delay of the optic disc in the arteriovenous phase as well as diffuse leakage of the optic disc in the late phase. Optical coherent tomography revealed increased thickness of the retinal nerve fiber layer, especially in the area of the inferior disc. The patient was counseled to discontinue the use of udenafil and to monitor his blood pressure regularly. The disc swelling was resolved with residual optic atrophy one month after discontinuing the use of udenafil.

Nonarteritic anterior ischemic optic neuropathy

PURPOSE OF REVIEW

Nonarteritic anterior ischemic optic neuropathy remains a disease that is poorly understood in many aspects. The clinical presentation may diverge significantly from the classic unilateral, painless, sudden vision loss affecting patients over the age of 50 years. This variability might make nonarteritic anterior ischemic optic neuropathy hard to differentiate from optic neuritis and arteritic ischemic optic neuropathy. The course of nonarteritic anterior ischemic optic neuropathy is also variable, often sequentially affecting the other eye.

RECENT FINDINGS

Visual recovery has been reported, but it is not the rule. Multiple risk factors have been proposed, including crowded disc, atherosclerosis, diabetes, hyperlipidemia, hypertension, hypotension, hemoconcentration, hemodilution, and hypercoagulable states. The optic nerve damage in nonarteritic anterior ischemic optic neuropathy appears to result from a perfusion insufficiency in the short posterior ciliary arteries leading to infarction of the retrolaminar portion of the optic disc. The underlying mechanisms are still unclear, however. Multiple medical and surgical treatment options have been investigated, including optic nerve sheath decompression, standard and megadose corticosteroids, levodopa, carbidopa, hyperbaric oxygen, and neuroprotective agents, but no proven effective treatment is currently available.

SUMMARY

Intense investigations in humans and animals are under way. Hopefully these studies will enhance our understanding of the risk factors and pathophysiology of nonarteritic anterior ischemic optic neuropathy and aid in developing new strategies for prevention and treatment.

Pathogenesis of nonarteritic anterior ischemic optic neuropathy

Based on histopathology, electron microscopic corrosion cast studies, optic nerve blood flow studies, and clinical data, the pathogenesis of idiopathic nonarteritic ischemic optic neuropathy includes the following features: (1) structurally crowded optic discs are predisposed; (2) laminar and retrolaminar regions are the most common locations for infarction; (3) there is flow impairment in the prelaminar optic disc during the acute phase; (4) lack of consistent choroidal flow impairment and the retrolaminar location of infarcts suggest vasculopathy within or distal to the paraoptic branches of the posterior choroidal arteries; (5) diabetes is the most consistently identified vasculopathic risk factor; (6) impaired autoregulation of the disc circulation by atherosclerosis, with a possible contribution from serotonin and endothelin-mediated vasospasm, may play a role; and (7) progression may be caused by secondary cell death after the initial ischemic insult or compression from cavernous degeneration and mechanical axonal distortion.