Imaging of the optic nerve: technological advances and future prospects

A systematic review of economic evaluation of artificial intelligence-based screening for eye diseases: From possibility to reality

Artificial Intelligence (AI) has become a focus of research in the rapidly evolving field of ophthalmology. Nevertheless, there is a lack of systematic studies on the health economics of AI in this field. We examine studies from the PubMed, Google Scholar, and Web of Science databases that employed quantitative analysis, retrieved up to July 2023. Most of the studies indicate that AI leads to cost savings and improved efficiency in ophthalmology. On the other hand, some studies suggest that using AI in healthcare may raise costs for patients, especially when taking into account factors such as labor costs, infrastructure, and patient adherence. Future research should cover a wider range of ophthalmic diseases beyond common eye conditions. Moreover, conducting extensive health economic research, designed to collect data relevant to its own context, is imperative.

Glaucoma as a cause of optic nerve abnormalities on magnetic resonance imaging

BACKGROUND/OBJECTIVES

To report a series of patients with glaucoma and optic nerve abnormalities on magnetic resonance imaging (MRI) in at least one-eye, and to determine whether these findings correlate with the severity of glaucoma.

PATIENTS AND METHODS

Retrospective study of all patients who underwent a brain/orbits MRI without and with contrast at our institution between 07/1/2019-6/30/2022. Patients with optic nerve T2-hyperintensity and/or MRI optic nerve atrophy in at least one-eye and a diagnosis of isolated glaucoma in at least one-eye were included. Demographic information, glaucoma clinical characteristics, glaucoma severity parameters, and MRI indication were collected.

RESULTS

Fifty-six patients (112 eyes) (age 65 years-old [range 26-88]; 70% male) had isolated bilateral glaucoma with at least one-eye MRI optic nerve abnormality. The indication for MRI was atypical/asymmetric glaucoma in 91% of patients. Of the 112 eyes, 23 had optic nerve T2-hyperintensity alone; 33 had both optic nerve T2-hyperintensity and MRI optic nerve atrophy; 34 had MRI optic nerve atrophy alone; and 22 did not have abnormal optic nerve MRI-findings. None had optic nerve enhancement. A statistically significant association between optic nerve T2-hyperintensity or MRI optic nerve atrophy and glaucoma severity parameters was found.

CONCLUSIONS

Glaucoma is a clinical diagnosis and MRI brain is usually not required, except in atypical or asymmetric cases. Optic nerve T2-hyperintensity and MRI optic nerve atrophy are nonspecific MRI-findings that can be found in severe glaucomatous optic nerves and should not systematically prompt investigations for another cause of optic neuropathy.

Genetic susceptibility to optic neuropathy in patients with alcohol use disorder

BACKGROUND

The pathophysiology of toxico-nutritional optic neuropathies remains debated, with no clear understanding of the respective roles played by the direct alcohol toxicity, smoking and the often associated vitamin deficiencies, which are risk factors for optic neuropathy. Our aim was to investigate genetic susceptibility in patients with bilateral infraclinical optic neuropathy associated with chronic alcohol use disorder.

METHODS

This retrospective cohort study included 102 visually asymptomatic patients with documented alcohol use disorder from a French reference center. Optic neuropathy was identified with optical coherence tomography (OCT), after which genetic susceptibility in the group of affected patients was investigated. Genetic testing was performed using panel sequencing of 87 nuclear genes and complete mitochondrial DNA sequencing.

RESULTS

Optic neuropathy was detected in 36% (37/102) of the included patients. Genetic testing of affected patients disclosed two patients (2/30, 6.7%) with optic neuropathy associated with pathogenic variants affecting the SPG7 gene and five patients (5/30, 16.7%) who harbored variants of uncertain significance close to probable pathogenicity in the genes WFS1, LOXL1, MMP19, NR2F1 and PMPCA. No pathogenic mitochondrial DNA variants were found in this group.

CONCLUSIONS

OCT can detect presence of asymptomatic optic neuropathy in patients with chronic alcohol use disorder. Furthermore, genetic susceptibility to optic neuropathy in this setting is found in almost a quarter of affected patients. Further studies may clarify the role of preventative measures in patients who might be predisposed to avoidable visual loss and blindness.

The Pseudotumor Cerebri Syndrome

Pseudotumor cerebri syndrome is a syndrome of increased cerebrospinal fluid pressure without ventriculomegaly, mass lesion, or meningeal abnormality. It is either primary (idiopathic intracranial hypertension, IIH) or secondary. A secondary cause is unlikely when adhering to the diagnostic criteria. Permanent visual loss occurs if undetected or untreated, and the associated headaches may be debilitating. Fulminant disease may result in blindness despite aggressive treatment. This study addresses the diagnosis and management of IIH including new insights into the pathobiology of IIH, updates in therapeutics and causes of overdiagnosis.

Application of a Deep Learning System to Detect Papilledema on Nonmydriatic Ocular Fundus Photographs in an Emergency Department

PURPOSE

The Fundus photography vs Ophthalmoscopy Trial Outcomes in the Emergency Department (FOTO-ED) studies showed that ED providers poorly recognized funduscopic findings in patients in the ED. We tested a modified version of the Brain and Optic Nerve Study Artificial Intelligence (BONSAI) deep learning system on nonmydriatic fundus photographs from the FOTO-ED studies to determine if the deep learning system could have improved the detection of papilledema had it been available to ED providers as a real-time diagnostic aid.

DESIGN

Retrospective secondary analysis of a cohort of patients included in the FOTO-ED studies.

METHODS

The testing data set included 1608 photographs obtained from 828 patients in the FOTO-ED studies. Photographs were reclassified according to the optic disc classification system used by the deep learning system ("normal optic discs," "papilledema," and "other optic disc abnormalities"). The system's performance was evaluated by calculating the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity using a 1-vs-rest strategy, with reference to expert neuro-ophthalmologists.

RESULTS

The BONSAI deep learning system successfully distinguished normal from abnormal optic discs (AUC 0.92 [95% confidence interval {CI} 0.90-0.93]; sensitivity 75.6% [73.7%-77.5%] and specificity 89.6% [86.3%-92.8%]), and papilledema from normal and others (AUC 0.97 [0.95-0.99]; sensitivity 84.0% [75.0%-92.6%] and specificity 98.9% [98.5%-99.4%]). Six patients with missed papilledema in 1 eye were correctly identified by the deep learning system as having papilledema in the other eye.

CONCLUSIONS

The BONSAI deep learning system was able to reliably identify papilledema and normal optic discs on nonmydriatic photographs obtained in the FOTO-ED studies. Our deep learning system has excellent potential as a diagnostic aid in EDs and non-ophthalmology clinics equipped with nonmydriatic fundus cameras. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Applying the 2022 optic neuritis criteria to noninflammatory optic neuropathies with optic nerve T2-hyperintensity: an observational study

INTRODUCTION

Recent diagnostic criteria for optic neuritis include T2-hyperintensity of the optic nerve (ON), even without associated contrast enhancement. However, isolated ON-T2-hyperintensity is a nonspecific finding found in any optic neuropathy or severe retinopathy. We applied the 2022 optic neuritis diagnostic criteria to a cohort of patients with noninflammatory optic neuropathy and ON-T2-hyperintensity in at least one eye, to assess the rate of optic neuritis misdiagnosis using these criteria.

METHODS

Retrospective study of consecutive patients who underwent brain/orbit MRI with/without contrast between 07/01/2019 and 06/30/2022. Patients with ON-T2-hyperintensity in at least one eye were included. The 2022 optic neuritis diagnostic criteria were applied to patients with noninflammatory optic neuropathies who had an ophthalmologic examination available for review.

RESULTS

Of 150 patients included, 85/150 had compressive optic neuropathy; 32/150 had glaucoma; 12/150 had papilledema; 8/150 had hereditary (3), radiation-induced (3), nutritional (1), traumatic (1) optic neuropathies (none fulfilled the criteria); 13/150 had ischemic optic neuropathy and 4 fulfilled the criteria as definite optic neuritis due to contrast enhancement of the ON head. Seven additional patients would have satisfied the diagnostic criteria if red flags for alternative diagnoses had been overlooked.

DISCUSSION

The application of the 2022 optic neuritis diagnostic criteria in patients with noninflammatory optic neuropathy and ON-T2-hyperintensity in at least one ON resulted in misdiagnosis of optic neuritis in only 4 patients because of ON head enhancement, all with nonarteritic anterior ischemic optic neuropathy. Neuro-ophthalmologic evaluation and exclusion of the ON head as a location in the MRI criteria would have prevented optic neuritis misdiagnosis in our study.

Interpretation of the Visual Field in Neuro-ophthalmic Disorders

PURPOSE OF REVIEW

In this review, we will describe current methods for visual field testing in neuro-ophthalmic clinical practice and research, develop terminology that accurately describes patterns of field deficits, and discuss recent advances such as augmented or virtual reality-based perimetry and the use of artificial intelligence in visual field interpretation.

RECENT FINDINGS

New testing strategies that reduce testing times, improve patient comfort, and increase sensitivity for detecting small central or paracentral scotomas have been developed for static automated perimetry. Various forms of machine learning-based tools such as archetypal analysis are being tested to quantitatively depict and monitor visual field abnormalities in optic neuropathies. Studies show that the combined use of optical coherence tomography and standard automated perimetry to determine the structure-function relationship improves clinical care in neuro-ophthalmic disorders. Visual field assessment must be performed in all patients with neuro-ophthalmic disorders affecting the afferent visual pathway. Quantitative visual field analysis using standard automated perimetry is critical in initial diagnosis, monitoring disease progression, and guidance of therapeutic plans. Visual field defects can adversely impact activities of daily living such as reading, navigation, and driving and thus impact quality of life. Visual field testing can direct appropriate occupational low vision rehabilitation in affected individuals.

Optic nerve topography in multiple sclerosis diagnostic criteria: Existing knowledge and future directions

Current diagnostic criteria for multiple sclerosis (MS) do not consider the optic nerve as a typical topography for establishing the diagnosis. Recent studies have proved the utility of optic nerve magnetic resonance imaging, optical coherence tomography and visual evoked potentials in detecting optic nerve lesions during the early stages of MS. In addition, emerging evidence supports the inclusion of optic nerve topography as a fifth region to fulfil the dissemination in space criteria. Anticipating a modification in the McDonald criteria, it is crucial for neurologists to familiarize with the diagnostic properties of each test in detecting optic nerve lesions and understand how to incorporate them into the MS diagnostic process. Therefore, the objective of this article is to review the existing evidence supporting the use of these tests in the diagnostic process of MS and provide a practical algorithm that can serve as a valuable guide for clinical practice.

Review of smartphone funduscopy for diabetic retinopathy screening

I detail advances in funduscopy diagnostic systems integrating smartphones. Smartphone funduscopy devices are comprised of lens devices connecting with smartphones and software applications to be used for mobile retinal image capturing and diagnosis of diabetic retinopathy. This is particularly beneficial to automate and mobilize retinopathy screening techniques and methods in remote and rural areas as those diabetes patients are often not meeting the required regular screening for diabetic retinopathy. Smartphone retinal image grading systems enable retinopathy to be screened remotely as teleophthalmology or as a stand-alone point-of-care-testing system. Smartphone funduscopy aims to avoid the need for patients to be seen by expert ophthalmologists, which can reduce patient travel, time taken for images to be processed, appointment backlog, health service overhead costs, and the workload burden for expert ophthalmologists.

The expanding spectrum of idiopathic intracranial hypertension

Once considered a rare and often difficult diagnosis in the era predating routine MRI, idiopathic intracranial hypertension has become an everyday concern in ophthalmology and neurology clinics where, especially in the latter, essentially every young overweight woman with headaches is initially presumed to have IIH. Has the diagnosis of IIH become too easy, and are we over-diagnosing IIH in this period of an accelerating obesity crisis? Or are we actually missing cases of IIH because they do not fit the classic clinical profile? We think it is both: at the same time IIH is being diagnosed in excess in obese women without papilledema, often resulting in unnecessary procedures, inappropriate treatment and even iatrogenic complications, the spectrum of this disorder is expanding to include a broad array of clinical presentations that involve multiple specialists beyond just the ophthalmologist and neurologist.

Diagnosis of Optic Disc Oedema: Fundus Features, Ocular Imaging Findings, and Artificial Intelligence

Optic disc swelling is a manifestation of a broad range of processes affecting the optic nerve head and/or the anterior segment of the optic nerve. Accurately diagnosing optic disc oedema, grading its severity, and recognising its cause, is crucial in order to treat patients in a timely manner and limit vision loss. Some ocular fundus features, in light of a patient's history and visual symptoms, may suggest a specific mechanism or aetiology of the visible disc oedema, but current criteria can at most enable an educated guess as to the most likely cause. In many cases only the clinical evolution and ancillary testing can inform the exact diagnosis. The development of ocular fundus imaging, including colour fundus photography, fluorescein angiography, optical coherence tomography, and multimodal imaging, has provided assistance in quantifying swelling, distinguishing true optic disc oedema from pseudo-optic disc oedema, and differentiating among the numerous causes of acute optic disc oedema. However, the diagnosis of disc oedema is often delayed or not made in busy emergency departments and outpatient neurology clinics. Indeed, most non-eye care providers are not able to accurately perform ocular fundus examination, increasing the risk of diagnostic errors in acute neurological settings. The implementation of non-mydriatic fundus photography and artificial intelligence technology in the diagnostic process addresses these important gaps in clinical practice.

Optic neuritis and autoimmune optic neuropathies: advances in diagnosis and treatment

Optic neuritis is an inflammatory optic neuropathy that is commonly indicative of autoimmune neurological disorders including multiple sclerosis, myelin-oligodendrocyte glycoprotein antibody-associated disease, and neuromyelitis optica spectrum disorder. Early clinical recognition of optic neuritis is important in determining the potential aetiology, which has bearing on prognosis and treatment. Regaining high-contrast visual acuity is common in people with idiopathic optic neuritis and multiple sclerosis-associated optic neuritis; however, residual deficits in contrast sensitivity, binocular vision, and motion perception might impair vision-specific quality-of-life metrics. In contrast, recovery of visual acuity can be poorer and optic nerve atrophy more severe in individuals who are seropositive for antibodies to myelin oligodendrocyte glycoprotein, AQP4, and CRMP5 than in individuals with typical optic neuritis from idiopathic or multiple-sclerosis associated optic neuritis. Key clinical, imaging, and laboratory findings differentiate these disorders, allowing clinicians to focus their diagnostic studies and optimise acute and preventive treatments. Guided by early and accurate diagnosis of optic neuritis subtypes, the timely use of high-dose corticosteroids and, in some instances, plasmapheresis could prevent loss of high-contrast vision, improve contrast sensitivity, and preserve colour vision and visual fields. Advancements in our knowledge, diagnosis, and treatment of optic neuritis will ultimately improve our understanding of autoimmune neurological disorders, improve clinical trial design, and spearhead therapeutic innovation.

Identification of a novel path for cerebrospinal fluid (CSF) drainage of the human brain

How cerebrospinal fluid (CSF) drains from the human brain is of paramount importance to cerebral health and physiology. Obstructed CSF drainage results in increased intra-cranial pressure and a predictable cascade of events including dilated cerebral ventricles and ultimately cell death. The current and accepted model of CSF drainage in humans suggests CSF drains from the subarachnoid space into the sagittal sinus vein. Here we identify a new structure in the sagittal sinus of the human brain by anatomic cadaver dissection. The CSF canalicular system is a series of channels on either side of the sagittal sinus vein that communicate with subarachnoid cerebrospinal fluid via Virchow-Robin spaces. Fluorescent injection confirms that these channels are patent and that flow occurs independent of the venous system. Fluoroscopy identified flow from the sagittal sinus to the cranial base. We verify our previous identification of CSF channels in the neck that travel from the cranial base to the subclavian vein. Together, this information suggests a novel path for CSF drainage of the human brain that may represent the primary route for CSF recirculation. These findings have implications for basic anatomy, surgery, and neuroscience, and highlight the continued importance of gross anatomy to medical research and discovery.