Optical coherence tomography use in idiopathic intracranial hypertension

Glaucoma: what the neurologist needs to know

Glaucoma is a progressive optic neuropathy resulting from pathological changes at the optic disc due to elevated intraocular pressure. Its diagnosis, treatment and follow-up are almost entirely conducted in ophthalmology clinics, with screening conducted by community optometrists. Despite this, neurologists may encounter glaucoma in both its acute presentation (as angle closure, presenting as acute headache) and its chronic forms (often as optic neuropathy of unknown cause). An awareness of the underlying pathological process, and the key distinguishing signs and symptoms, will allow neurologists to identify the glaucomatous process rapidly. Timely referral is essential as glaucoma invariably results in progressive visual loss without treatment. This review therefore condenses the wide field of glaucoma into a practical summary, aimed at practitioners with limited clinical experience of this ophthalmic condition.

Non-invasive assessment of intracranial pressure through the eyes: current developments, limitations, and future directions

Detecting and monitoring elevated intracranial pressure (ICP) is crucial in managing various neurologic and neuro-ophthalmic conditions, where early detection is essential to prevent complications such as seizures and stroke. Although traditional methods such as lumbar puncture, intraparenchymal and intraventricular cannulation, and external ventricular drainage are effective, they are invasive and carry risks of infection and brain hemorrhage. This has prompted the development of non-invasive techniques. Given that direct, non-invasive access to the brain is limited, a significant portion of research has focused on utilizing the eyes, which uniquely provide direct access to their internal structure and offer a cost-effective tool for non-invasive ICP assessment. This review explores the existing non-invasive ocular techniques for assessing chronically elevated ICP. Additionally, to provide a comprehensive perspective on the current landscape, invasive techniques are also examined. The discussion extends to the limitations inherent to each technique and the prospective pathways for future advancements in the field.

Optical coherence tomography angiography analysis in patients with intracranial hypertension

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Exploring the utility of retinal optical coherence tomography as a biomarker for idiopathic intracranial hypertension: a systematic review

This study aimed to examine the existing literature that investigated the effectiveness of optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A) as a biomarker for idiopathic intracranial hypertension (IIH). Our search was conducted on January 17th, 2024, and included the databases, Medline, Scopus, Embase, Cochrane, Latin American and Caribbean Health Sciences Literature (LILACS), International Standard Randomized Controlled Trial Number (ISRCTN) registry, and the International Clinical Trials Registry Platform (ICTRP). Our final review included 84 articles. In 74 studies, OCT was utilized as the primary ocular imaging method, while OCT-A was employed in two studies including eight studies that utilized both modalities. Overall, the results indicated that IIH patients exhibited significant increases in retinal nerve fiber layer (RNFL) thickness, total retinal and macular thickness, optic nerve head volume, and height, optic disc diameter and area, rim area, and thickness compared to controls. A significant correlation was observed between cerebrospinal fluid (CSF) pressure and OCT parameters including RNFL thickness, total retinal thickness, macular thickness, optic nerve head volume, and optic nerve head height. Interventions aimed at lowering CSF pressure were associated with a substantial improvement in these parameters. Nevertheless, studies comparing peripapillary vessel density using OCT-A between IIH patients and controls yielded conflicting results. Our systematic review supports OCT as a powerful tool to accurately monitor retinal axonal and optic nerve head changes in patients with IIH. Future research is required to determine the utility of OCT-A in IIH.

Application of novel non-invasive ophthalmic imaging to visualize peripapillary wrinkles, retinal folds and peripapillary hyperreflective ovoid mass-like structures associated with elevated intracranial pressure

Background

Elevated intracranial pressure (ICP) is a serious and potentially life-threatening condition, for which clinically useful non-invasive measures have been elusive, in some cases due to their inadequate sensitivity and specificity. Our aim was to evaluate novel non-invasive ophthalmic imaging of selected pathological features seen in elevated ICP, namely peripapillary hyperreflective ovoid mass-like structures (PHOMS), peripapillary wrinkles (PPW) and retinal folds (RF) as potential biomarkers of elevated ICP.

Methods

This single-center pilot study included subjects with untreated or incompletely treated high ICP. The retinas of these subjects were evaluated with averaged en-face optical coherence tomography (OCT), OCT retinal cross-sections (OCT B-scans), adaptive optics scanning light ophthalmoscopy (AOSLO), and fundus photos.

Results

Seven subjects were included in the study. 6 subjects with high ICP (5 idiopathic intracranial hypertension, 1 medication induced, 30.8 ± 8.6 years, 75% female, 5 with papilledema) and 1 control (20-25 years) were included. PHOMS, PPW and RF were present in all subjects with papilledema, but neither in the high ICP subject without papilledema nor in the control subject. Averaged en-face OCT scans and AOSLO were more sensitive for PPW and RF than OCT B-scans and commercial fundus photos.

Conclusion

PPW, RF and PHOMS volume have potential as non-invasive biomarkers of ICP. Novel imaging modalities may improve sensitivity. However, lack of automated image acquisition and processing limits current widespread adoption in clinical settings. Further research is needed to validate these structures as biomarkers for elevated ICP and improve clinical utility.

Advantages and Pitfalls of the Use of Optical Coherence Tomography for Papilledema

PURPOSE OF REVIEW

Papilledema refers to optic disc swelling caused by raised intracranial pressure. This syndrome arises from numerous potential causes, which may pose varying degrees of threat to patients. Manifestations of papilledema range from mild to severe, and early diagnosis is important to prevent vision loss and other deleterious outcomes. The purpose of this review is to highlight the role of optical coherence tomography (OCT) in the diagnosis and management of syndromes of raised intracranial pressure associated with papilledema.

RECENT FINDINGS

Ophthalmoscopy is an unreliable skill for many clinicians. Optical coherence tomography is a non-invasive ocular imaging technique which may fill a current care gap, by facilitating detection of papilledema for those who cannot perform a detailed fundus examination. Optical coherence tomography may help confirm the presence of papilledema, by detecting subclinical peripapillary retinal nerve fiber layer (pRNFL) thickening that might otherwise be missed with ophthalmoscopy. Enhanced depth imaging (EDI) and swept source OCT techniques may identify optic disc drusen as cause of pseudo-papilledema. Macular ganglion cell inner plexiform layer (mGCIPL) values may provide early signs of neuroaxonal injury in patients with papilledema and inform management for patients with syndromes of raised intracranial pressure. There are well-established advantages and disadvantages of OCT that need to be fully understood to best utilize this method for the detection of papilledema. Overall, OCT may complement other existing tools by facilitating detection of papilledema and tracking response to therapies.  Moving forward, OCT findings may be included in deep learning models to diagnose papilledema.

CSF hyperdynamics in rats mimicking the obesity and androgen excess characteristic of patients with idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a syndrome exhibiting elevated intracranial pressure (ICP), visual disturbances, and severe headache. IIH primarily affects young obese women, though it can occur in individuals of any age, BMI, and sex. IIH is characterized by systemic metabolic dysregulation with a profile of increased androgen hormones. However, the contribution of obesity/hormonal perturbations to cerebrospinal fluid (CSF) dynamics remains unresolved.

METHODS

We employed obese female Zucker rats and adjuvant testosterone to reveal IIH causal drivers. ICP and CSF dynamics were determined with in vivo experimentation and magnetic resonance imaging, testosterone levels assessed with mass spectrometry, and choroid plexus function revealed with transcriptomics.

RESULTS

Obese rats had undisturbed CSF testosterone levels and no changes in ICP or CSF dynamics. Adjuvant testosterone treatment of obese rats elevated the CSF secretion rate, although with no effect on the ICP, due to elevated CSF drainage capacity of these rats.

CONCLUSIONS

Obesity in itself therefore does not suffice to recapitulate the IIH symptoms in rats, but modulation of CSF dynamics appears with adjuvant testosterone treatment, which mimics the androgen excess observed in female IIH patients. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH and could potentially serve as a future therapeutic target.

Optic Nerve Head and Retinal Changes in Idiopathic Intracranial Hypertension: Correlation with Short-Term Cerebrospinal Fluid Pressure Monitoring

BACKGROUND

We aimed to assess the status of the optic nerve and retina by optical coherence tomography (OCT) in a group of patients with idiopathic intracranial hypertension (IIH) on the basis of dynamic changes in intracranial pressure.

METHODS

This observational and cross-sectional study included patients affected by idiopathic intracranial hypertension with papilledema (IIHWP) and patients with idiopathic intracranial hypertension without papilledema (IIHWOP). All participants underwent an OCT examination of the macula and optic nerve head. Parameters related to intracranial pressure, including cerebrospinal fluid (CSF) opening pressure (oCSFp), CSF mean pressure (mCSFp), and pulse wave amplitude (PWA), were included in the analysis.

RESULTS

Out of the 22 subjects enlisted for the study, a total of 16 patients suggestive of IIH were finally enrolled. Papilledema was detected in nine subjects (56.2%) and seven patients were affected by IIHWOP (43.7%). The OCT examination showed a higher mean RNFL thickness in IIHWP patients in comparison to IIHWOP in both eyes (p < 0.05 and p < 0.01, respectively). Intracranial pressure (ICP) measurements showed that IIHWP had higher values of oCSFp, mCSFp, and PWA compared to IIHWOP (p = 0.0001, p = 0.0001, and p = 0.0001, respectively). In addition, ICP parameters significantly correlated with RNFL.

CONCLUSIONS

Clinical parameters suggestive of idiopathic intracranial hypertension are associated with retina and optic nerve OCT parameters. OCT is a useful tool to detect these alterations in a non-invasive fashion.

Idiopathic intracranial hypertension in Omani adults: A tertiary center experience

BACKGROUND

To evaluate the clinical profile, risk factors, and ophthalmic diagnostic and monitoring tools in Omani patients with idiopathic intracranial hypertension (IIH) using optical coherence tomography (OCT).

METHODS

A retrospective single institutional cohort study on Omani patients with a fulfilled diagnosis of IIH from January 1, 2014, to January 1, 2020, was conducted. The data obtained from the neuro-ophthalmic clinic contained age of onset of the disease, gender of patients, body mass index (BMI), presence of other associated conditions, and medication use.

RESULTS

Our study group comprised 21 patients with IIH with an annual incidence rate of 2.8 per 100,000 population. Female-to-male ratio was 9.5:1 with a mean age of 27.24 ± 7.1. Headaches appeared to be the most prevalent symptom in 21 (100%) patients, followed by transient obscuration of vision in 9 (42.9%) patients and diplopia in 3 (14.3%) patients, and the least common symptom was pulsatile tinnitus in 2 (9.5%) patients. Increased BMI was seen in 19 (90.5%) patients and noted to be the most prevalent predisposing factor among our study group. The use of oral contraceptive pills was documented in 4 (19%) patients and 1 (4.8%) patient was noted to have polycystic ovary syndrome. All patients (100%) had a best-corrected visual acuity of 1.0 in both eyes pre- and postrecovery and 7 (33.3%) patients had an enlarged blind spot on visual field testing. All patients had papilledema on presentation and an average of 14.1 months to resolve to normal clinically and on OCT monitoring. All patients were treated with medications and only 1 (4.8%) continued to have intractable headaches that did not respond to maximum medical therapy and required surgery.

CONCLUSION

The incidence of IIH in the Omani population was found to be less than neighboring countries but comparable worldwide. OCT is considered a useful tool to confirm and document papilledema and more importantly monitor recovery.

Optic Nerve Head Changes Measured by Swept Source Optical Coherence Tomography and Angiography in Patients with Intracranial Hypertension

INTRODUCTION

This study explored the structural and microvascular changes in the optic nerve head (ONH) of patients with intracranial hypertension (IH) by using swept-source optical coherence tomography (SS-OCT)/OCT angiography (OCTA) and evaluated their association with clinical features.

METHODS

The optic disc morphology, peripapillary retinal nerve fiber layer (pRNFL), ganglion cell-inner plexiform layer (GCIPL), and microvascular densities of the nerve fiber layer plexus (NFLP), superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) were measured by the SS-OCT/OCTA tool. Frisen score, visual acuity, and intracranial pressure were assessed and recorded in patients with IH.

RESULTS

Sixty-one patients with IH and 65 controls were included in this study. Patients with IH showed thicker pRNFL and GCIPL thickness with larger ONH rim area when compared to controls (P < 0.001). Microvascular densities were increased in NFLP while densities were reduced in SVP, ICP, and DCP when compared to controls (P < 0.001). Structural thickness and microvascular densities were significantly correlated with Frisen scores (P < 0.05) and intracranial pressure (P < 0.05) in patients with IH.

CONCLUSION

Structural and microvasculature variations of the ONH were found in patients with IH compared to controls. Importantly, we showed that structural and microvascular changes in the ONH were correlated with their Frisen score and intracranial pressure in patients with IH.

Idiopathic intracranial hypertension: a step change in understanding the disease mechanisms

The understanding of idiopathic intracranial hypertension (IIH) has evolved over the past few years. Previously, IIH was considered a disease exclusively affecting the neuro-ophthalmic axis, characterized by raised intracranial pressure, headache and papilloedema, and resulting in the risk of severe and permanent visual loss and life-changing disabling headaches. Recent advances have begun to redefine IIH as a probable metabolic disease involving a range of systemic manifestations. More than 95% of individuals affected by the disease are women of reproductive age with obesity. The incidence is rapidly rising and parallels the escalating worldwide obesity rates. Contemporary insights identify associations with insulin resistance, type 2 diabetes and a twofold increased risk of cardiovascular disease in excess of that driven by obesity alone. Adipose distribution in people with IIH, like that in other metabolic diseases, is preferentially centripetal and is associated with changes in intracranial pressure. Evidence now demonstrates adipose tissue dysfunction in people with IIH, involving transcriptional and metabolic priming for lipogenesis and weight gain. Hormonal perturbations are also observed, including a unique phenotype of androgen excess that promotes cerebrospinal fluid secretion. Knowledge of these additional disease features is driving research into novel therapeutic targets and altering the approach to multidisciplinary care.

The use of artificial intelligence in detecting papilledema from fundus photographs

Papilledema is an optic disc swelling with increased intracranial pressure as the underlying cause. Diagnosis of papilledema is made based on ophthalmoscopy findings. Although important, ophthalmoscopy can be challenging for general physicians and nonophthalmic specialists. Meanwhile, artificial intelligence (AI) has the potential to be a useful tool for the detection of fundus abnormalities, including papilledema. Even more, AI might also be useful in grading papilledema. We aim to review the latest advancement in the diagnosis of papilledema using AI and explore its potential. This review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A systematic literature search was performed on four databases (PubMed, Cochrane, ProQuest, and Google Scholar) using the Keywords "AI" and "papilledema" including their synonyms. The literature search identified 372 articles, of which six met the eligibility criteria. Of the six articles included in this review, three articles assessed the use of AI for detecting papilledema, one article evaluated the use of AI for papilledema grading using Frisèn criteria, and two articles assessed the use of AI for both detection and grading. The models for both papilledema detection and grading had shown good diagnostic value, with high sensitivity (83.1%-99.82%), specificity (82.6%-98.65%), and accuracy (85.89%-99.89%). Even though studies regarding the use of AI in papilledema are still limited, AI has shown promising potential for papilledema detection and grading. Further studies will help provide more evidence to support the use of AI in clinical practice.

Noninvasive methods to monitor intracranial pressure

PURPOSE OF REVIEW

Intracranial pressure (ICP) is determined by the production of and outflow facility of cerebrospinal fluid. Since alterations in ICP are implicated in several vision-threatening and life-threatening diseases, measurement of ICP is necessary and common. All current clinical methods to measure ICP are invasive and carry the risk for significant side effects. Therefore, the development of accurate, reliable, objective, and portal noninvasive devices to measure ICP has the potential to change the practice of medicine. This review discusses recent advances and barriers to the clinical implementation of noninvasive devices to determine ICP.

RECENT FINDINGS

Many noninvasive methods to determine ICP have been developed. Although most have significant limitations limiting their clinical utility, several noninvasive methods have shown strong correlations with invasively obtained ICP and have excellent potential to be developed further to accurately quantify ICP and ICP changes.

SUMMARY

Although invasive methods remain the mainstay for ICP determination and monitoring, several noninvasive biomarkers have shown promise to quantitatively assess and monitor ICP. With further refinement and advancement of these techniques, it is highly possible that noninvasive methods will become more commonplace and may complement or even supplant invasively obtained methods to determine ICP in certain situations.

Tunable alginate hydrogels as injectable drug delivery vehicles for optic neuropathy

Many disease pathologies, particularly in the eye, are induced by oxidative stress. In particular, injury to the optic nerve (ON), or optic neuropathy, is one of the most common causes of vision loss. Traumatic optic neuropathy (TON) occurs when the ON is damaged following blunt or penetrating trauma to either the head or eye. Currently, there is no effective treatment for TON, only management options, namely the systematic delivery of corticosteroids and surgical decompression of the optic nerve. Unfortunately, neither option alleviates the generation of reactive oxygen species (ROS) which are responsible for downstream damage to the ON. Additionally, the systemic delivery of corticosteroids can cause fatal off‐target effects in cases with brain involvement. In this study, we developed a tunable injectable hydrogel delivery system for local methylene blue (MB) delivery using an internal method of crosslinking. MB was chosen due to its ROS scavenging ability and neuroprotective properties. Our MB‐loaded polymeric scaffold demonstrated prolonged release of MB as well as in situ gel formation. Additionally, following rheological characterization, these alginate hydrogels demonstrated minimal cytotoxicity to human retinal pigment epithelial cells in vitro and exhibited injection feasibility through small‐gauge needles. Our chosen MB concentrations displayed a high degree of ROS scavenging following release from the alginate hydrogels, suggesting this approach may be successful in reducing ROS levels following ON injury, or could be applied to other ocular injuries.

Clinical profile and retinal nerve fibre layer thickness of optic disc oedema patients at a tertiary care institute in North India

Background:

Optic disc oedema (ODE) is an important manifestation in various ocular as well as systemic disorders. Measurement of retinal nerve fibre layer (RNFL) thickness in ODE patients may help in monitoring the progress of the disease and treatment response.

Objective:

To assess the clinical characteristics, aetiology and retinal nerve fibre layer (RNFL) imaging features of optic disc oedema (ODE) patients.

Design:

A retrospective observational study.

Methods:

This hospital-based study included performed for patients presenting with unilateral or bilateral ODE at the ophthalmology outpatient department of a tertiary institute between January 2019 and December 2019. Clinical features of all ODE patients were noted. RNFL thickness was measured by spectral-domain optical coherence tomography (Cirrus 500, Carl Zeiss Meditec, Dublin, CA, USA).

Results:

Sixty-four patients with ODE were seen with female preponderance (56.2%). The mean age of presentation was 36.8 ± 13.8 years. Bilateral ODE was seen in 57.8% patients. The most common cause of bilateral ODE was idiopathic intracranial hypertension (IIH) and vascular papillopathy. Retinal vein occlusion (RVO)-associated ODE was the most common unilateral presentation. Presenting visual acuity was best with IIH and worst with anterior ischaemic optic neuropathy (AION). The mean duration of symptoms was maximum with intracranial space-occupying lesion associated papilloedema and minimum with AION. The mean RNFL thickness was highest in uveitis-associated ODE, followed by compressive ON, and IIH. A positive correlation was noted between clinical ODE severity and RNFL thickness. All aetiological categories (except uveitic and compressive) had maximum RNFL thickening in the inferior quadrant and minimum in the temporal quadrant.

Conclusion:

The current study provides a clinical profile and RNFL measurements of ODE patients at this locality. The clinical severity of ODE correlated positively with RNFL thickness and most of the categories of ODE followed the normative pattern of RNFL thickness (inferior > superior > nasal > temporal) despite thickening.

Resolution of Papilledema Following Ventriculoperitoneal Shunt or Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus: A Pilot Study

Background and Objectives: Ventriculoperitoneal Shunt (VPS) and Endoscopic Third Ventriculostomy (ETV) are both gold standard procedures to reduce intracranial pressure (ICP) in patients with obstructive hydrocephalus, which often results in papilledema. This comparative study was carried out at the Department of Neurosurgery of Dhaka Medical College and Hospital to compare the efficacy of VPS and ETV in the resolution of papilledema in 18 patients with obstructive hydrocephalus. Materials and Methods: The success of CSF diversion was evaluated by a decrease in retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) and modified Frisen grading of papilledema at the same time. The statistical analyses were carried out by using paired sample t test and the Spearman's correlation coefficient test. The level of significance (p value) was set at <0.05. Results: After 7 days, both VPS and ETV were able to reduce RNFL thickness of both eyes with a p value = 0.016 (right eye) and 0.003 (left eye) in group A (VPS) and with a p value <0.001 (both eyes) in group B (ETV). Change of Frisen grading after CSF diversion was not satisfying for both the procedures with p value > 0.05. Further, the inter-group comparison between VPS and ETV showed no difference in decreasing RNFL thickness and modified Frisen grading (p value = 0.56). Conclusion: VPS and ETV procedures both appear very efficient in treating obstructive hydrocephalus, which in turn reduces papilledema in these patients. This paper is preliminary and requires further work.

Application of optic neuro-ophthalmology imaging in latent meningeal metastases of lung cancer

Latent intracranial meningeal metastases (IMM) of lung cancer is difficult to determine, yet it is critical to do so given that it impacts the treatment agent. Studies on this disease are rare, thus necessitating further investigation. As a case study, we will explore the application of optic neuroimaging in IMM. A 62-year-old female patient was diagnosed with lung adenocarcinoma, which had progressed to osseous metastasis. During the course of chemotherapy, the patient had bilateral vision loss and paralysis of extraocular muscles. Ophthalmologists ruled out disease of the retina and suspected intracranial metastasis; however, brain-enhanced magnetic resonance angiography and magnetic resonance venography were normal. Given the patient's severe osteoarthropathy and poor physical condition, she refused to undergo a lumbar puncture examination. Optic neuro-ophthalmology imaging was ultimately used. Utilizing optical coherence tomography, we found that the basement membrane layer in the papilledema was protruding up towards the vitreous cavity. To assist in visualization, the optic nerve sheath was enhanced with optic magnetic resonance imaging. With these methods, the dural metastasis was identified, the treatment agent was changed for the patient, and she had a successful recovery. Thus, optic neuro-ophthalmology imaging should be recommended for patients who are in the latent course of dural metastasis, and it could also be used to evaluate therapeutic efficacy.

Optical coherence tomography: a window to the brain?

First described in 1991 and introduced into clinical practice in 1996, optical coherence tomography (OCT) now has a very extensive role in many different areas of ophthalmological practice. It is non-invasive, cheap, highly reproducible, widely available and easy to perform. OCT also has a role in managing patients with neurological disorders, particularly idiopathic intracranial hypertension. This review provides an overview of the technology underlying OCT and the information it can provide that is relevant to the practising neurologist. Particular conditions discussed include papilloedema, optic disc drusen, multiple sclerosis and neuromyelitis optica, other optic neuropathies, compression of the anterior visual pathway and various neurodegenerative conditions.

The role of optical coherence tomography in the diagnosis of afferent visual pathway problems: A neuroophthalmic perspective

Optical coherence tomography (OCT) is a noninvasive ocular imaging technique that has become a standard tool in neuroophthalmic practice. Specifically, OCT captures retinal manifestations of neuroaxonal injury caused by lesions along anterior and posterior regions of the afferent visual pathway, in patients presenting with vision loss. More recently, the advent of OCT angiography (OCTA) has enabled evaluation of the choroidal and retinal microvasculature, thus informing our understanding regarding vascular mechanisms associated with optic nerve and retinal injuries. Much of our longitudinal experience with OCT in the field of neuroophthalmology has been acquired from the study of optic neuritis (ON) caused by inflammatory disorders of the central nervous system (CNS). Over the past two decades, OCT has emerged as a surrogate endpoint for CNS neuroaxonal injury in multiple sclerosis (MS) research trials. On a more pragmatic level, OCT is used in the clinical arena to diagnose ON associated with: MS, neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody associated disease (MOGAD). Subsequent advancements in swept-source (SS) and enhanced depth imaging (EDI) have established OCT as the new "gold standard" in the diagnosis of optic disc drusen. Recent studies have highlighted pathognomonic OCT features that distinguish cases of true papilledema from pseudopapilledema, in patients presenting with undifferentiated optic disc elevation. Preoperative OCT measures of neuroaxonal integrity have shown prognostic value in predicting postoperative visual outcomes for patients with compressive anterior visual pathway lesions. Finally, OCT is indispensable in differentiating optic neuropathies from retinal diseases in patients with visual loss and a nondiagnostic fundus examination. An in-depth discussion regarding the technical aspects of OCT is beyond the scope of this chapter. Instead, we wish to highlight the value OCT brings to the diagnosis and management of common neuroophthalmic conditions, with emphasis on optic neuropathies and retinal disorders.

Reviewing the Recent Developments in Idiopathic Intracranial Hypertension

There is increasing evidence and appreciation of idiopathic intracranial hypertension (IIH) in medicine. The pathological processes underlying raised intracranial pressure are being studied, with new insights found in both hormonal dysregulation and the metabolic neuroendocrine axis. These will potentially lead to novel therapeutic targets for IIH. The first consensus guidelines have been published on the investigation and management of adult IIH, and the International Headache Society criteria for headache attributable to IIH have been modified to reflect our evolving understanding of IIH. Randomized clinical trials have been published, and a number of studies in this disease area are ongoing.