The swollen optic nerve: an approach to diagnosis and management

NAION or not NAION? A literature review of pathogenesis and differential diagnosis of anterior ischaemic optic neuropathies

PURPOSE

To offer a comprehensive review of the available data regarding non-arteritic anterior ischaemic optic neuropathy and its phenocopies, focusing on the current evidence to support the different existing aetiopathogenic hypotheses for the development of these conditions.

CONCLUSIONS AND IMPORTANCE

Due to the limited array of responses of the neural tissue and other retinal structures, different aetiopathogenic mechanisms may result in a similar clinical picture. Moreover, when the insult occurs within a confined space, such as the optic nerve or the optic nerve head, in which different tissues (neural, glial, vascular) are highly interconnected and packed together, determining the primary noxa can be challenging and may lead to misdiagnosis. Anterior ischaemic optic neuropathy is a condition most clinicians will face during their everyday work, and it is important to correctly differentiate among resembling pathologies affecting the optic nerve to avoid unnecessary diagnostic procedures. Combining a good clinical history and multimodal imaging can assist diagnosis in most cases. The key remains to combine demographic data (e.g. age), with ophthalmic data (e.g. refractive error), systemic data (e.g. comorbidities and medication), imaging data (e.g. retinal OCT) with topographic signs (e.g. focal neurology).

METHODOLOGY

Papers relevant for this work were obtained from the MEDLINE and Embase databases by using the PubMed search engine. One author (MPMG) performed the search and selected only publications with relevant information about the aetiology, pathogenic mechanisms, risk factors as well as clinical characteristics of phenocopies (such as vitreopapillary traction, intrapapillary haemorrhage with adjacent peripapillary subretinal haemorrhage or diabetic papillopathy) of non-arteritic anterior ischaemic optic neuropathy (NAION). The terms "non-arteritic ischaemic optic neuropathy/NAION", "vitreopapillary traction", "vitreopapillary traction AND non-arteritic ischaemic optic neuropathy/NAION", "posterior vitreous detachment AND non-arteritic ischaemic optic neuropathy/NAION", "central retinal vein occlusion AND non-arteritic ischaemic optic neuropathy/NAION", "disc oedema/disc oedema", "diabetes mellitus AND non-arteritic ischaemic optic neuropathy/NAION" and "diabetic papillopathy" were searched on PubMed. From each of these searches, publications were selected based on their title, obtaining a total of 115 papers. All papers not written in English were then excluded, and those whose abstracts were not deemed relevant for our review, according to the aforementioned criteria. Subsequent scrutiny of the main text of the remaining publications led us (MPMG, AP, ZS) to include references which had not been selected during our first search, as their titles did not contain the previously mentioned MeSH terms, due to their significantly relevant contents for our work. A total of 62 publications were finally consulted for our review. The literature review was last updated on 24-Aug-2022.

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.

The Causes of Optic Disc Edema in Patients Presenting With Significantly Compromised Vision

BACKGROUND

To evaluate the most common causes of optic disc edema (ODE) in patients with significantly compromised vision (initial best-corrected visual acuity [BCVA] of 20/400 or worse) at presentation.

METHODS

Retrospective chart review over a 5-year period of consecutive patients presenting to tertiary neuro-ophthalmology clinics at the University of Toronto.

RESULTS

A total of 656 patients with ODE were included, and 49 patients (7.47%) had an initial BCVA of 20/400 or worse. There were 54 eyes included at baseline and 49 eyes at final follow-up. There were 29 female and 20 male patients. The mean age at first visit across patients was 55.9 years. Female patients (n = 29) were significantly older than male patients (n = 20) (P < 0.05). The causes of ODE were optic neuritis (ON) (n = 22; 40.7%), nonarteritic anterior ischemic optic neuropathy (NAION) (n = 22; 40.7%), arteritic anterior ischemic optic neuropathy (AAION) (n = 5; 9.26%), uveitis-related (n = 3; 5.56%), papilledema from idiopathic intracranial hypertension (IIH) (n = 1; 1.85%), and Vogt-Koyanagi-Harada disease (n = 1; 1.85%). Initial BCVA was not significantly different between ON and NAION groups (P = 0.52); however, final BCVA was significantly better in the ON group (P < 0.0001). The mean initial BCVA was worst in the AAION group (2.62 ± 0.54 logarithm of the minimum angle of resolution). The most common cause of ODE in patients <40 years old was ON (83.3%), whereas the 2 most common causes in patients >80 were NAION (60%) and AAION (40%). In patients between the ages of 60-80, NAION (100%) was the only cause.

CONCLUSIONS

Patients with ODE and poor vision at presentation represent a minority of cases seen in neuro-ophthalmology clinics (<10%). Optic neuritis and NAION are the 2 most common causes of ODE with poor vision at presentation. These findings are limited by a small sample size and potential sampling bias.

Clinical approach to a child with hemophagocytic lymphohistiocytosis and bilateral optic nerve head infiltration: A case report and brief literature review

Key Clinical Message

Infiltrative optic neuropathy in hemophagocytic lymphohistiocytosis is rare but could potentially lead to visual loss. Cytomegalovirus (CMV) optic neuritis, drug toxicity, and CNS involvement with increased intracranial pressure (ICP) are differential diagnoses that have to be considered.

Abstract

In this report, we introduced a known case of hemophagocytic lymphohistiocytosis (HLH) with progressive visual loss due to bilateral optic nerve head (ONH) involvement. A 9-year-old boy with a history of HLH from 6 months ago was referred to the ophthalmic emergency department with a complaint of painless progressive blurred vision in his right eye. The fundus examination found an optic disc swelling and peripapillary hemorrhage in the right eye. The left fundus examination showed a mild ONH blurred margin. Systemic evaluations including brain and orbital MRI with gadolinium enhancement and CSF analysis showed optic nerve and brain involvement with tumoral cells. Despite systemic chemotherapy with etoposide, the disease had a progressive course so in the last follow-up visit, fundus examination revealed disc swelling, retinal edema, and epiretinal hemorrhage in both eyes and visual acuity deteriorated to no light perception and counting fingers in the right and left eye, respectively. ONH involvement in HLH is rare but could be sight-threatening. Differential diagnoses that should be investigated include neoplastic infiltrative optic neuropathy, cytomegalovirus (CMV) optic neuritis, drug toxicity, and CNS involvement with increased intracranial pressure (ICP).

Clinical approach for suspected optic disc swelling in children: recommendations based on a six-year review

CLINICAL RELEVANCE

Suspected optic disc swelling is a common presentation in children. The delineation between true optic disc swelling and pseudopapilloedema, its common masquerade, requires careful evaluation. A streamlined pathway is required to avoid unnecessary investigations.

BACKGROUND

Papilloedema requires urgent neuroimaging, however, perceived optic disc swelling is not always true papilloedema. This study aims to investigate the outcome of referrals for optic disc swelling and formulate features that may assist in investigation and diagnosis.

METHODS

A retrospective review of referrals for optic disc swelling to the Queensland Children's Hospital, Australia, between January 2014 and June 2020 was undertaken.

RESULTS

Four hundred and ten children were referred for optic disc swelling. Sixty-six patients were confirmed with optic disc swelling, and 344 patients had pseudopapilloedema. The average age was 10.10 ± 3.57 and 9.90 ± 3.50 years, respectively. The most common aetiology of optic disc swelling was idiopathic intracranial hypertension (n = 25). Optic disc drusen constituted the majority of pseudopapilloedema (n = 239) and the remainder were crowded/tilted discs (n = 105). True optic disc swelling patients were more likely to experience headache (OR = 8.68, p < 0.01) and visual disturbance (OR = 2.14, p = 0.03). B-scan was the most sensitive for the detection of optic disc drusen (100%), followed by optical coherence tomography (70.38%) and fundus autofluorescence (44.86%). The retinal nerve fibre layer thickness was significantly thicker in true optic disc swelling compared to pseudopapilloedema (p < 0.01). Twenty-two (33.33%) true optic disc swelling patients and 33 (9.59%) pseudopapilloedema patients underwent neuroimaging prior to ophthalmology review.

CONCLUSIONS

Suspected optic disc swelling in children is most likely pseudopapilloedema. Referrals should include neurological assessment, visual acuity, fundus photography, and optical coherence tomography to assist in the triage for ophthalmic review. Neuroimaging prior to ophthalmic review should be discouraged for children without neurological symptoms.

[Typical and atypical optic neuritis]

Optic neuritis (ON) is one of the most common neuro-ophthalmic causes of vision loss worldwide. Demyelinating ON can be idiopathic or be one of the symptoms of autoimmune demyelinating diseases of the central nervous system (CNS) such as multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Demographic, clinical and radiological signs of ON in these CNS diseases have differences. In this regard, typical and atypical ON are currently distinguished. Recognizing the clinical features that differentiate typical MS-associated ON from atypical ON in NMOSD and MOGAD is important for choosing the correct disease management and treatment strategy. This review summarizes the data from clinical, laboratory, instrumental methods of management used for the differential diagnosis of optic neuritis.

Papilledema: A review of etiology, pathophysiology, diagnosis, and management

Papilledema is optic nerve head edema secondary to raised intracranial pressure (ICP). It is distinct from other causes of optic disk edema in that visual function is usually normal in the acute phase. Papilledema is caused by transmission of elevated ICP to the subarachnoid space surrounding the optic nerve that hinders axoplasmic transport within ganglion cell axons. There is ongoing controversy as to whether axoplasmic flow stasis is produced by physical compression of axons or microvascular ischemia. The most common cause of papilledema, especially in patients under the age of 50, is idiopathic intracranial hypertension (IIH); however, conditions that decrease cerebrospinal fluid (CSF) outflow by either causing CSF derangements or mechanically blocking CSF outflow channels, and rarely conditions that increase CSF production, can be the culprit. When papilledema is suspected clinically, blood pressure should be measured, and pseudopapilledema should be ruled out. Magnetic resonance imaging of the brain and orbits with venography sequences is the preferred neuroimaging modality that should be performed next to look for indirect imaging signs of increased ICP and to rule out nonidiopathic causes. Lumbar puncture with measurement of opening pressure and evaluation of CSF composition should then be performed. In patients not in a typical demographic group for IIH, further investigations should be conducted to assess for underlying causes of increased ICP. Magnetic resonance imaging of the neck and spine, magnetic resonance angiography of the brain, computed tomography of the chest, complete blood count, and creatinine testing should be able to identify most secondary causes of intracranial hypertension. Treatment for patients with papilledema should be targeted toward the underlying etiology. Most patients with IIH respond to weight loss and oral acetazolamide. For patients with decreased central acuity and constricted visual fields at presentation, as well as patients who do not respond to treatment with acetazolamide, surgical treatments should be considered, with ventriculoperitoneal shunting being the typical procedure of choice.

Visual fields and optical coherence tomography (OCT) in neuro-ophthalmology: Structure-function correlation

Visual field (VF) testing is an essential component of the neurological examination. The differential diagnosis of VF defects depends on relating this measure of afferent visual function to the structure of the visual pathway and optical coherence tomography (OCT) is an invaluable tool for detailed structural evaluation of the optic nerve and retina. This review describes the ways in which interpretation of VF and OCT can be used together to increase the accuracy of the localization of lesions along the visual pathway. Lesions of the anterior visual pathway (originating in ganglion cells or nerve fibre layer of the retina or optic nerve) will typically produce defects that respect the horizontal midline, reflecting the arcuate path of the ganglion cell axons as they travel to the optic nerve. OCT of peripapillary retinal nerve fibre layer and ganglion cell complex (GCC) will typically demonstrate irreversible thinning in compressive and demyelinating lesions affecting anterior visual pathway. Chiasmal lesions produce highly localizable VF defects (junctional scotoma and bitemporal hemianopia) which correspond to the thinning of nasal portion of GCC. Lesions of the optic tract result in incongruous homonymous hemianopia on VF with corresponding hemianopic thinning on GCC developing within months. Lesions affecting optic radiations usually produce more congruous homonymous VF defects and can also produce homonymous thinning on GCC, however, this takes much longer to develop as trans-synaptic degeneration at the lateral geniculate body must occur.

Optical Coherence Tomography to Monitor Rebound Intracranial Hypertension with Increased Papilledema after Lumbar Puncture

Objective: We report that lumbar puncture (LP) with removal of cerebrospinal fluid (CSF) induced rebound intracranial hypertension with increased papilledema as monitored by optical coherence tomography (OCT). Background: Severe papilledema causes visual field loss and central vision damage if untreated. Fundoscopy is a key to diagnose papilledema, but is not sensitive enough to monitor therapeutic effects. Methods: OCT was applied to follow a 24-year-old woman with headache, visual dysfunction, severe bilateral papilledema, and elevated CSF opening pressure. She was first treated with serial LP, which led to symptom deterioration, increased CSF pressure, and increased the retinal nerve fiber layer (RNFL) thickness. She was then successfully treated with acetazolamide and furosemide. Results: OCT showed reduction of RNFL thickness directly after LP with CSF removal, accompanied with reduced CSF pressure. Increased RNFL thickness accompanied with worsened headache, visual dysfunction, and increased CSF pressure was observed on the next day after LP. Less than 24 h after start of medication, the symptoms had reversed and RNFL thickness was reduced. The patient was symptom-free 2 weeks after starting on medical treatment. Papilledema had vanished on fundoscopy 6 weeks after the therapy, and RNFL thickness was normalized at 3 months of follow-up. Conclusion: This case provides evidence that OCT is an objective and sensitive tool to monitor papilledema and its response to therapy, and thereby important to help in correct clinical decision-making.

Analysis of the Peripapillary Choroidal Vascular Characteristics in Papilledema Associated with Pseudotumor Cerebri

SIGNIFICANCE

Choroidal vascularity index measured by image binarization method from peripapillary optical coherence tomography sections has been found significantly lower in papilledema patients than healthy controls.

PURPOSE

The purpose of this study was to compare peripapillary choroidal parameters in papilledema patients with control subjects.

METHODS

Peripapillary spectral domain optical coherence tomography scans of 34 patients with papilledema and 34 healthy controls are acquired for the study. Images are binarized with the ImageJ software (National Institutes of Health, Bethesda, MD) to calculate total choroidal area, stromal area, luminal area, and choroidal vascularity index.

RESULTS

Total choroidal area, luminal area, and choroidal vascularity were significantly lower in papilledema patients compared with healthy controls on right (1.343 ± 0.286 vs. 1.694 ± 0.344, P < .001; 0.880 ± 0.209 vs. 1.167 ± 0.255, P < .001; 65.28 ± 2.99% vs. 68.68 ± 2.81%, P < .001, respectively) and left eyes (1.376 ± 0.308 vs. 1.647 ± 0.339, P < .001; 0.899 ± 0.231 vs. 1.134 ± 0.237, P < .001; 64.92 ± 3.44 vs. 68.84 ± 3.23, P < .001, respectively). No difference was found between active and remitted stages of papilledema in terms of choroidal parameters.

CONCLUSIONS

Peripapillary total choroidal area, luminal area, and choroidal vascularity index are significantly reduced in patients with papilledema. These parameters might be beneficial tools for evaluating choroidal vascularity in papilledema quantitatively and differential diagnosis for optic disc edema.

Approach to patient with unilateral optic disc edema and normal visual function

In patients with swollen optic nerve head and normal visual function, optic disc drusen (ODD) is the most common diagnosis. The best tests for detecting ODD are funds autofluorescence and enhanced-depth imaging ocular coherence tomography (EDIOCT). After ODD has been ruled out, asymmetric papilledema should be assumed to be the cause and MRI of the brain and orbits with contrast and venography should be performed in all patients. It allows one to look for indirect signs of increased inctracranial pressure (ICP), optic perineuritis, and other inflammatory or compressive processes affecting optic nerve or its sheath such as optic nerve sheath meningioma. If imaging signs of raised ICP are present, lumbar puncture should be performed with measurement of opening pressure and analysis of cerebrospinal fluid (CSF) contents in all patients with fever, meningismus or neurologic deficits as well as patients who are not in the typical demographic group for idiopathic intracranial hypertension (IIH). Optic nerve sheath enhancement on MRI should prompt work-up for causes of optic perineuritis. When the appropriate neuroimaging is normal, the differential diagnosis is limited and ophthalmological consultation is necessary to determine whether other subtle ocular abnormalities are present on biomicroscopic and dilated fundus examination.

Late-onset Leber's hereditary optic neuropathy presenting with longitudinally extensive myelitis harbouring the m.14484T>C mutation: Extending the genotype-phenotype spectrum

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disease leading to visual loss, typically in young men, and rarely displays extra-ocular manifestations including spinal cord disease. We report the case of a 57-year-old man who presented with a longitudinally extensive dorsal column lesion as the first manifestation of LHON, with the onset of bilateral progressive optic neuropathy 11 months later, harbouring the m.14484T>C mutation. To our knowledge this is the most extensive cord lesion preceding optic neuropathy traversing the cervical and thoracic cord. We review the literature of all published cases of LHON in which spinal cord involvement was the presenting feature of the disease, summarising the clinical phenotype, demographics, radiological characteristics and genotype. We highlight the importance for diagnostic vigilance in patients with either longitudinally extensive dorsal column myelopathy, optic neuropathy or both.

Neuroretinitis in a young woman

•Neuroretinitis is unilateral optic nerve head edema followed 2-4 weeks later by development of macular star.•Typically, severe optic nerve head edema is out of keeping with relatively preserved visual function.•As the site of pathology are leaky capillaries on optic nerve head and not optic nerve axons, RAPD is mild or not present.•Most cases are either idiopathic or secondary to specific infectious etiologies.•Patients with neuroretinitis are not at risk of developing multiple sclerosis and do not require neuro-imaging in most cases.