Optical coherence tomography of the swollen optic nerve head: deformation of the peripapillary retinal pigment epithelium layer in papilledema

Differentiating between mild papilledema and pseudopapilledema on fundus photography

OBJECTIVE

True papilledema can be difficult to distinguish from pseudopapilledema, especially if mild. Tele-ophthalmology allows fundus photos of suspected disc edema to be sent remotely to neuro-ophthalmologists for their expert interpretation. This study evaluated the ability of neuro-ophthalmologists to discriminate papilledema from pseudopapilledema in mild cases of optic disc swelling based on fundus photographs, with and without patient information.

METHODS

Fundus photographs from 55 patients referred to two neuro-ophthalmology centers for suspicion of papilledema with mild optic disc swelling were reviewed. Patients with normal visual function and no evidence of secondary intracranial hypertension were included. Strict definitions were used to define papilledema and pseudopapilledema. Three neuro-ophthalmologists rated fundus photos as either papilledema or pseudopapilledema before and after the provision of patient age, sex, body mass index (BMI), and visual acuity.

RESULTS

Twenty-nine patients fulfilled criteria for the papilledema group and 26 in the pseudopapilledema group. Fifty-one subjects were female, average age was 32.8 years, and average BMI was 30.9 kg/m2. When photos were rated in isolation, overall accuracy was 59.4 % and inter-rater reliability was poor (k = 0.052). The true positive rate was 56.3 %, true negative rate 62.8 %, false positive rate 37.2 %, and false negative rate 43.7 %. Providing patient information improved overall accuracy to 64.2 % and inter-rater reliability to k = 0.37.

CONCLUSIONS

It is difficult even for neuro-ophthalmologists to correctly distinguish mild papilledema from pseudopapilledema based on fundus photographs alone. Providing basic patient information in telemedicine referrals can improve clinical appraisal and guide the invasiveness of investigations.

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.

Clinical characteristics of peripapillary hyperreflective ovoid mass-like structures in myopic children

AIM

To describe the characteristics of peripapillary hyperreflective ovoid mass-like structure (PHOMS) in myopic children and to investigate factors associated with PHOMS.

METHODS

This retrospective observational study included 101 eyes of 101 children (age ≤17y) with myopia. All included patients underwent comprehensive clinical examination. Optic nerve canal parameters, including disc diameter, optic nerve head (ONH) tilt angle, and border tissue angle were measured using serial enhanced-depth imaging spectral-domain optical coherence tomography (EDI-OCT). Based on the optic disc drusen consortium's definition of PHOMS, eyes were classified as PHOMS group and non-PHOMS group. PHOMS was categorized according to height.

RESULTS

Sixty-seven (66.3%) eyes were found with PHOMS. Small PHOMS could only be detected by optical coherence tomography (OCT). Medium PHOMS could be seen with blurred optic disc borders corresponding to OCT. The most frequent location of PHOMS was at the nasosuperior (91%, 61 of 67 eyes) to ONH disc. The axial length and spherical equivalent were more myopic in the PHOMS group than in the non-PHOMS group (both P<0.001). ONH tilt angle was also significantly greater in PHOMS group than in non-PHOMS group [8.90 (7.16-10.54) vs 3.93 (3.09-5.25), P<0.001]. Border tissue angle was significantly smaller in PHOMS group than in non-PHOMS group [29.70 (20.90-43.81) vs 45.62 (35.18-60.45), P<0.001]. In the multivariable analysis, spherical equivalent (OR=3.246, 95%CI=1.209-8.718, P=0.019) and ONH tilt angle (OR=3.275, 95%CI=1.422-7.542, P=0.005) were significantly correlated with PHOMS. There was no disc diameter associated with PHOMS. In the linear regression analysis, border tissue angle was negatively associated with PHOMS height (β=-2.227, P<0.001).

CONCLUSION

PHOMS is associated with optic disc tilt and optic disc nasal shift in myopia. Disc diameter is not a risk factor for PHOMS. The changes in ONH caused by axial elongation facilitated an understanding of the mechanism of PHOMS.

Thickened Retinal Nerve Fiber Layer Without Hypermyelination in Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay

Purpose: To report the retinal findings in a patient with autosomal recessive spastic ataxia of Charlevoix-Saguenay. Methods: A case was evaluated. Results: A 16-year-old male patient with a known diagnosis of autosomal recessive spastic ataxia of Charlevoix-Saguenay was referred for evaluation of retinal hypermyelination given its frequent association with the condition. The patient was asymptomatic with a best-corrected visual acuity of 20/20. Optical coherence tomography of the peripapillary retinal nerve fiber layer (RNFL) showed bilateral thickening in each eye (average thicknesses: 180 µm, right eye; 177 µm, left eye). An examination showed no myelinization of the RNFL. Conclusions: Most studies to date describe RNFL thickening secondary to hypermyelination as a characteristic finding in autosomal recessive spastic ataxia of Charlevoix-Saguenay. This case provides evidence that this thickening may be a result of hypertrophy rather than hypermyelination. Further investigation is needed to define the pathophysiologic cause of RNFL thickening in autosomal recessive spastic ataxia of Charlevoix-Saguenay.

Diagnostic dilemma of papilledema and pseudopapilledema

BACKGROUND

Papilledema is the optic disc swelling caused by increased intracranial pressure (ICP) that can damage the optic nerve and cause subsequent vision loss. Pseudopapilledema refers to optic disc elevation without peripapillary fluid that can arise from several optic disc disorders, with optic disc drusen (ODD) being the most frequent cause. Occasionally, pseudopapilledema patients are mistakenly diagnosed as papilledema, leading to the possibility of unneeded procedures. We aim to thoroughly examine the most current evidence on papilledema and pseudopapilledema causes and several methods for distinguishing between both conditions.

METHODS

An extensive literature search was conducted on electronic databases including PubMed and google scholar using keywords that were relevant to the assessed pathologies. Data were collected and then summarized in comprehensive form.

RESULTS

Various techniques are employed to distinguish between papilledema and pseudopapilledema. These techniques include Fundus fluorescein angiography, optical coherence tomography, ultrasonography, and magnetic resonance imaging. Lumbar puncture and other invasive procedures may be needed if results are suspicious.

CONCLUSION

Papilledema is a sight-threatening condition that may lead to visual affection. Many disc conditions may mimic papilledema. Accordingly, differentiation between papilledema and pseudopailledema is crucial and can be conducted through many modalities.

Case report: Unilateral papilledema in a dog with a large suprasellar mass and suspected intracranial hypertension: insights from funduscopy, optical coherence tomography, and magnetic resonance imaging

A spayed, 8-year-old female Poodle, weighing 5.7 kg, was presented with the chief complaint of vision impairment. Vision assessment, including pupillary light reflexes, menace response, dazzle reflex, and maze navigation in photopic and scotopic circumstances, revealed a negative response in both eyes except for positive direct pupillary light reflex in the right eye and positive consensual pupillary light reflex from the right eye to the left eye. Systemic evaluation, including neurologic status, blood profile, and thoracic radiographs, did not reveal any abnormalities. Complete ophthalmic examinations, ocular ultrasonography, and electroretinography did not identify a cause of blindness. Upon funduscopy, the left eye exhibited an increased optic disk diameter, blurred optic disk borders, and loss of the physiologic pit, as well as an increase in vascular tortuosity. In the right eye, there were multifocal depigmented areas in the non-tapetal fundus and several pigmented spots surrounded by a region of dull tapetal reflection in the tapetal fundus. The optical coherence tomography revealed severe anterior deformation of the optic nerve head and Bruch's membrane in the peripapillary region of the left eye. Magnetic resonance imaging revealed an irregular, broad-based suprasellar mass, with features suggestive of intracranial hypertension, including dorsal displacement of third ventricles, a rightward shift of the falx cerebri, trans-tentorial herniation, perilesional edema, flattening/protrusion of the posterior sclera, and lager optic nerve sheath diameter in left side than right side. This is the first comprehensive report that describes unilateral papilledema in a dog with a brain tumor, using advanced ophthalmic and neuro-imaging modalities.

Optical coherence tomography in papilledema: A probe into the intracranial pressure correlation

PURPOSE

To study the optic nerve head characteristics on optical coherence tomography (OCT) in patients with papilledema and correlate them with intracranial pressure (ICP).

METHODS

A retrospective hospital-based study of 46 eyes of 23 patients with bilateral optic disc edema secondary to increased ICP. The clinical profile and the OCT features in terms of retinal nerve fiber layer thickness (RNFL), ganglion cell inner plexiform layer (GCIPL) thickness, and enhanced depth imaging (EDI) B scan images of the optic nerve head were studied and correlated with the ICP.

RESULTS

Papilledema was secondary to idiopathic intracranial hypertension (IIH) ( n = 20), obstructive hydrocephalus ( n = 2), and communicating hydrocephalus ( n = 1). The mean ICP in 20 IIH patients was 347 mmH 2 O. The ICP and RNFL thickness in all four quadrants were found to be weakly positively correlated: superior RNFL r (38) = 0.17, P = 0.30, and nasal RNFL r (38) = 0.30, P = 0.05, inferior RNFL r (38) = 0.29, P = 0.07, and temporal RNFL, r (38) = -0.001, P = 0.99. The GCIPL layer thickness and the ICP were weakly negatively correlated in all sectors: superior (38) = -0.23, P = 0.16, superonasal, r (38) = -0.07, P = 0.67, inferonasal r (38) = -0.08, P = 0.64, inferior r (38) = -0.21, P = 0.19, inferotemporal r (38) = -0.23, P = 0.17, superotemporal, r (38) -0.21, P = 0.20. Descriptive features on the B scan, such as peripapillary hyperreflective ovoid mass-like structures and microcystic spaces, were observed most commonly with an ICP of 251-350 mmH 2 O, and the hyperreflective dots in the RNFL layer and Bruch's membrane inward denting were observed more commonly with an ICP of 351-450 mmH 2 O.

CONCLUSION

The RNFL thickness in all four quadrants had a weak positive correlation, and the GCIPL layer had a weak negative correlation with the ICP. The EDI descriptive features on OCT may vary with ICP.

The current status of noninvasive intracranial pressure monitoring: A literature review

Elevated intracranial pressure (ICP) is a life-threatening condition that must be promptly diagnosed. However, the gold standard methods for ICP monitoring are invasive, time-consuming, and they involve certain risks. To address these risks, many noninvasive approaches have been proposed. This study undertakes a literature review of the existing noninvasive methods, which have reported promising results. The experimental base on which they are established, however, prevents their application in emergency conditions and thus none of them are capable of replacing the traditional invasive methods to date. On the other hand, contemporary methods leverage Machine Learning (ML) which has already shown unprecedented results in several medical research areas. That said, only a few publications exist on ML-based approaches for ICP estimation, which are not appropriate for emergency conditions due to their restricted capability of employing the medical imaging data available in intensive care units. The lack of such image-based ML models to estimate ICP is attributed to the scarcity of annotated datasets requiring directly measured ICP data. This ascertainment highlights an active and unexplored scientific frontier, calling for further research and development in the field of ICP estimation, particularly leveraging the untapped potential of ML techniques.

Sustained Retinal Defocus Increases the Effect of Induced Myopia on the Retinal Astrocyte Template

The aim of this article is to describe sustained myopic eye growth's effect on astrocyte cellular distribution and its association with inner retinal layer thicknesses. Astrocyte density and distribution, retinal nerve fiber layer (RNFL), ganglion cell layer, and inner plexiform layer (IPL) thicknesses were assessed using immunochemistry and spectral-domain optical coherence tomography on seventeen common marmoset retinas (Callithrix jacchus): six induced with myopia from 2 to 6 months of age (6-month-old myopes), three induced with myopia from 2 to 12 months of age (12-month-old myopes), five age-matched 6-month-old controls, and three age-matched 12-month-old controls. Untreated marmoset eyes grew normally, and both RNFL and IPL thicknesses did not change with age, with astrocyte numbers correlating to RNFL and IPL thicknesses in both control age groups. Myopic marmosets did not follow this trend and, instead, exhibited decreased astrocyte density, increased GFAP+ spatial coverage, and thinner RNFL and IPL, all of which worsened over time. Myopic changes in astrocyte density, GFAP+ spatial coverage and inner retinal layer thicknesses suggest astrocyte template reorganization during myopia development and progression which increased over time. Whether or not these changes are constructive or destructive to the retina still remains to be assessed.

Recent advances in the use of optical coherence tomography in neuro-ophthalmology: A review

Optical coherence tomography (OCT) is an in vivo imaging modality that provides non-invasive, high resolution and fast cross-sectional images of the optic nerve head, retina and choroid. OCT angiography (OCTA) is an emerging tool. It is a non-invasive, dye-free imaging approach of visualising the microvasculature of the retina and choroid by employing motion contrast imaging for blood flow detection and is gradually receiving attention for its potential roles in various neuro-ophthalmic and retinal conditions. We will review the clinical utility of the OCT in the management of various common neuro-ophthalmic and neurological disorders. We also review some of the OCTA research findings in these conditions. Finally, we will discuss the limitations of OCT as well as introduce other emerging technologies.

Which OCT Measure of the Optic Nerve Head Improves Fastest? Towards Optimizing Early Detection of Resolving Papilledema in Children

Purpose

Optical coherence tomography (OCT) has been used to monitor papilledema. This study aims to determine which OCT-derived measures of the optic nerve head (ONH) detect resolving papilledema in children faster than standard OCT measures.

Methods

Children (≤18 years of age) with papilledema who completed optic nerve SD-OCT pretreatment and had evidence of treatment response on one or more follow-up OCTs within 4 months were included. Standard (mean circumpapillary retinal nerve fiber layer [cpRNFL] thickness), device-derived (per-quadrant cpRNFL) and custom (ONH height, maximum Bruch's membrane displacement [BMD], ONH volume [ONHV], and BMD volume) OCT measures were calculated. Per-eye generalized estimating equations (GEEs) modelled changes in device-derived and custom measures as a function of mean cpRNFL to identify those measures that resolved faster during early (0-2 months) follow-up. Mean cpRNFL coefficients of greater than 1 indicated faster resolving papilledema.

Results

We included 52 eyes of 29 children (mean age, 12.8 years; 72.4% female). In analysis of early follow-up visits (38 eyes from 22 children), nasal cpRNFL and maximum BMD in each quadrant resolved faster than mean cpRNFL (GEE coefficients range, 1.14-3.37). Inferior cpRNFL, superior, nasal, and inferior ONH heights and ONHV resolved slower than mean cpRNFL (GEE coefficients range, 0.67-0.87).

Conclusions

Nasal cpRNFL is a promising device-derived OCT measure for the early detection of resolving papilledema in children compared with mean cpRNFL. Maximum BMD, a custom measure, also shows promise, but its calculation has not yet been incorporated into commercial OCT devices.

Translational Relevance

This study guides the optimal use of OCT in capturing resolving papilledema in children.

Importance of Ophthalmological Evaluation in the Conservative Management of Increased Intracranial Pressure from a Ruptured Arachnoid Cyst

Arachnoid cysts (ACs) are cerebrospinal fluid collections between the two layers of the normal arachnoid membrane. Although they are often asymptomatic with a stationary course, eventual complications may occur. Herein, we report the case of a 9-year-old boy who developed bilateral papilloedema secondary to spontaneous rupture of an AC in the left middle cranial fossa. Although the papilloedema worsened during follow-up, his visual field remained bilaterally stable, supporting the expectant management and obviating the potential morbidity associated with neurosurgical intervention. This case report highlights the importance of a multidisciplinary approach to patients with secondary intracranial hypertension, including serial ophthalmological examinations, which provide a useful guide to surgical decision-making.

A Review of the Methods of Non-Invasive Assessment of Intracranial Pressure through Ocular Measurement

The monitoring of intracranial pressure (ICP) is essential for the detection and treatment of most craniocerebral diseases. Invasive methods are the most accurate approach to measure ICP; however, these methods are prone to complications and have a limited range of applications. Therefore, non-invasive ICP measurement is preferable in a range of scenarios. The current non-invasive ICP measurement methods comprise fluid dynamics, and ophthalmic, otic, electrophysiological, and other methods. This article reviews eight methods of non-invasive estimation of ICP from ocular measurements, namely optic nerve sheath diameter, flash visual evoked potentials, two-depth transorbital Doppler ultrasonography, central retinal venous pressure, optical coherence tomography, pupillometry, intraocular pressure measurement, and retinal arteriole and venule diameter ratio. We evaluated and presented the indications and main advantages and disadvantages of these methods. Although these methods cannot completely replace invasive measurement, for some specific situations and patients, non-invasive measurement of ICP still has great potential.

Changes in Optic Nerve Head and Retinal Morphology During Spaceflight and Acute Fluid Shift Reversal

Importance

Countermeasures that reverse the headward fluid shift experienced in weightlessness have the potential to mitigate spaceflight-associated neuro-ocular syndrome. This study investigated whether use of the countermeasure lower-body negative pressure during spaceflight was associated with changes in ocular structure.

Objective

To determine whether changes to the optic nerve head and retina during spaceflight can be mitigated by brief in-flight application of 25-mm Hg lower-body negative pressure.

Design, Setting, and Participants

In the National Aeronautics and Space Administration's "Fluid Shifts Study," a prospective cohort study, optical coherence tomography scans of the optic nerve head and macula were obtained from US and international crew members before flight, in-flight, and up to 180 days after return to Earth. In-flight scans were obtained both under normal weightless conditions and 10 to 20 minutes into lower-body negative pressure exposure. Preflight and postflight data were collected in the seated, supine, and head-down tilt postures. Crew members completed 6- to 12-month missions that took place on the International Space Station. Data were analyzed from 2016 to 2021.

Interventions or Exposures

Spaceflight and lower-body negative pressure.

Main Outcomes and Measures

Changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thickness, and macular thickness.

Results

Mean (SD) flight duration for the 14 crew members (mean [SD] age, 45 [6] years; 11 male crew members [79%]) was 214 (72) days. Ocular changes on flight day 150, as compared with preflight seated, included an increase in minimum rim width (33.8 μm; 95% CI, 27.9-39.7 μm; P < .001), decrease in cup volume (0.038 mm3; 95% CI, 0.030-0.046 mm3; P < .001), posterior displacement of Bruch membrane opening (-9.0 μm; 95% CI, -15.7 to -2.2 μm; P = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; P < .001). Brief exposure to lower-body negative pressure did not affect these parameters.

Conclusions and Relevance

Results of this cohort study suggest that peripapillary tissue thickening, decreased cup volume, and mild central macular thinning were associated with long-duration spaceflight. Acute exposure to 25-mm Hg lower-body negative pressure did not alter optic nerve head or retinal morphology, suggesting that longer durations of a fluid shift reversal may be needed to mitigate spaceflight-induced changes and/or other factors are involved.

Optical coherence tomography features and correlation of functional and structural parameters in patients of idiopathic intracranial hypertension

Purpose:

To determine the correlation between functional parameters and optical coherence tomography (OCT) features in patients of idiopathic intracranial hypertension (IIH).

Methods:

A prospective observational study in early and established cases of papilledema in IIH presenting from December 2017 to February 2019. Functional parameters (visual acuity, contrast sensitivity, mean deviation, VER, and MfERG) and structural parameters (RNFL, GCL-IPL, and optic disc height) were measured at baseline and every 6 weeks for 6 months.

Results:

At baseline, average RNFL had a moderate negative correlation with mean deviation (r = −0.45; P = 0.0007) and a positive correlation with logMAR visual acuity (r = 0.18; P = 0.17). On the contrary, baseline GCL and logMAR visual acuity had a negative correlation (r = −0.4, P = 0.02). Optic disc height (ODH) had a negative correlation with visual field mean deviation (r = −0.046; P = 0.0005). At 6 months, ODH and GCL-IPL complex had a statistically significant correlation with functional parameters. However, RNFL values did not show any significant correlation with any of the functional parameters. Baseline GCL-IPL and optic disc height values had a moderate and significant correlation with final functional parameters. However, RNFL did not show any correlation with final functional parameters. Correlation between GCL-IPL thickness at 6 weeks and final functional parameters were stronger than that with baseline GCL values

Conclusion:

In the setting of severe papilledema, RNFL can misguide the prognosis. GCL-IPL can be a valuable tool for an objective evaluation of the integrity of the optic nerve in IIH and ODH may be used as an alternative or in combination with GCL-IPL in these cases.

Noninvasive Estimation of Pulsatile and Static Intracranial Pressure by Optical Coherence Tomography

Purpose

To explore the ability of optical coherence tomography (OCT) to noninvasively estimate pulsatile and static intracranial pressure (ICP).

Methods

An OCT examination was performed in patients who underwent continuous overnight monitoring of the pulsatile and static ICP for diagnostic purpose. We included two patient groups, patients with idiopathic intracranial hypertension (IIH; n = 20) and patients with no verified cerebrospinal fluid disturbances (reference; n = 12). Several OCT parameters were acquired using spectral-domain OCT (RS-3000 Advance; NIDEK, Singapore). The ICP measurements were obtained using a parenchymal sensor (Codman ICP MicroSensor; Johnson & Johnson, Raynham, MA, USA). The pulsatile ICP was determined as the mean ICP wave amplitude (MWA), and the static ICP was determined as the mean ICP.

Results

The peripapillary Bruch's membrane angle (pBA) and the optic nerve head height (ONHH) differed between the IIH and reference groups and correlated with both MWA and mean ICP. Both OCT parameters predicted elevated MWA. Area under the curve and cutoffs were 0.82 (95% confidence interval [CI], 0.66–0.98) and -0.65° (sensitivity/specificity; 0.75/0.92) for pBA and 0.84 (95% CI, 0.70–0.99) and 405 µm (0.88/0.67) for ONHH. Adjusting for age and body mass index resulted in nonsignificant predictive values for mean ICP, whereas the predictive value for MWA remained significant.

Conclusions

This study provides evidence that the OCT parameters pBA and ONHH noninvasively can predict elevated pulsatile ICP, represented by the MWA.

Translational Relevance

OCT shows promise as a method for noninvasive estimation of ICP.

Effects of Acute Intracranial Pressure Changes on Optic Nerve Head Morphology in Humans and Pig Model

PURPOSE

The lamina cribrosa (LC) is a layer of fenestrated connective tissue tethered to the posterior sclera across the scleral canal in the optic nerve head (ONH). It is located at the interface of intracranial and intraocular compartments and is exposed to intraocular pressure (IOP) anteriorly and intracranial pressure (ICP) or Cerebrospinal fluid (CSF) pressure (CSFP) posteriorly. We hypothesize that the pressure difference across LC will determine LC position and meridional diameter of scleral canal (also called Bruch's membrane opening diameter; BMOD).

METHODS

We enrolled 19 human subjects undergoing a medically necessary lumbar puncture (LP) to lower CSFP and 6 anesthetized pigs, whose ICP was increased in 5 mm Hg increments using a lumbar catheter. We imaged ONH using optical coherence tomography and measured IOP and CSFP/ICP at baseline and after each intervention. Radial tomographic ONH scans were analyzed by two independent graders using ImageJ, an open-source software. The following ONH morphological parameters were obtained: BMOD, anterior LC depth and retinal thickness. We modeled effects of acute CSFP/ICP changes on ONH morphological parameters using ANOVA (human study) and generalized linear model (pig study).

RESULTS

For 19 human subjects, CSFP ranged from 5 to 42 mm Hg before LP and 2 to 19.4 mm Hg after LP. For the six pigs, baseline ICP ranged from 1.5 to 9 mm Hg and maximum stable ICP ranged from 18 to 40 mm Hg. Our models showed that acute CSFP/ICP changes had no significant effect on ONH morphological parameters in both humans and pigs.

CONCLUSION

We conclude that ONH does not show measurable morphological changes in response to acute changes of CSFP/ICP. Proposed mechanisms include compensatory and opposing changes in IOP and CSFP/ICP and nonlinear or nonmonotonic effects of IOP and CSFP/ICP across LC.

Variability Within Optic Nerve Optical Coherence Tomography Measurements Distinguishes Papilledema From Pseudopapilledema

BACKGROUND

To report a linear risk score obtained using clock-hour optical coherence tomography (OCT) data from papilledema and pseudopapilledema nerves that differentiates between the 2 diagnoses with high sensitivity and specificity.

METHODS

Patients presenting to a single neuro-ophthalmologist with papilledema or pseudopapilledema were included for a retrospective review. The absolute consecutive difference in OCT retinal nerve fiber layer (RNFL) thickness between adjacent clock hours and the mean magnitude of thickness for clock hours 1-12 were compared between the 2 groups using mixed-effect models adjusting for age and clock hour with a random intercept for subjects and eyes (nested within subject). The area under the curve (AUC) for the receiver operating characteristics curve and a separate calibration curve was used to evaluate potential clinical usage.

RESULTS

Forty-four eyes with papilledema and 72 eyes with pseudopapilledema, 36 of whom had optic nerve drusen met criteria. The papilledema group had a higher mean RNFL thickness (papilledema = 163 ± 68 µm, pseudopapilledema = 82 ± 22 µm, P < 0.001). The papilledema groups also had more variability between consecutive clock hours (papilledema = 57 ± 20 µm, pseudopapilledema = 26 ± 11 µm, P < 0.001). A linear combination of each patient's averaged values separated the 2 groups with an AUC of 98.4% (95% CI 95.5%-100%) with an optimized sensitivity of 88.9% and specificity of 95.5% as well as good calibration (mean absolute error = 0.015).

CONCLUSIONS

Patients with papilledema have higher intrinsic variability and magnitude within their OCT, and this finding reliably distinguishes them from those with pseudopapilledema.

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.

Retinal and Optic Nerve Deformations Due to Orbital Versus Intracranial Venous Hypertension

INTRODUCTION

Abnormal forces around the optic nerve head (ONH) due to orbital diseases, intracranial hypertension (IH), glaucoma, and space travel, are associated with alterations of the ONH shape. Elevated cerebral and ophthalmic venous pressure can contribute to stress and strain on the ONH and peripapillary retina. We hypothesize that IH and elevated ophthalmic venous pressure without IH cause different ONH and retinal changes.

METHODS

We compared MRI and spectral domain optical coherence tomography (SDOCT) findings in patients with cavernous sinus arteriovenous shunts (CSAVSs), where orbital venous pressure is known to be elevated, with patients with intracranial dural venous sinus thrombosis and secondary IH. We also compared the results to those obtained in the Idiopathic IH (IIH) Treatment Trial.

RESULTS

Among 18 patients with dural venous sinus thrombosis, the MRI/magnetic resonance venography displayed partial empty sella (61%) and optic nerve sheath distension (67%). None exhibited ophthalmic vein dilation or signs of orbital congestion. SDOCT of these eyes and IIH eyes showed a similar frequency of abnormal thickening of the mean retinal nerve fiber layer, anterior displacement of the basement membrane opening, peripapillary wrinkles, retinal folds (RF), and choroidal folds (CF). Among 21 patients with CSAVSs, MRI showed ipsilateral dilated superior ophthalmic vein (76%) and orbital congestion (52%) without distension of the optic nerve sheath or globe distortion. SDOCT showed CF (19%), one with overlying RF, and no ONH deformations.

CONCLUSIONS

SDOCT findings for dural venous sinus thrombosis are similar to those seen with IIH but distinct from changes due to local ophthalmic venous hypertension. These data support the concept that IH even if due to a vascular cause and local orbital venous hypertension cause different stresses and strains on the ONH.

Role of spectral domain optical coherence tomography in the diagnosis and prognosis of papilledema

Purpose:

The study of papilledema with a novel noninvasive technique such as spectral domain-optical coherence tomography (SD-OCT) provides minute and detailed cross-sectional changes thus giving an insight into the application of biomechanical principles and pathophysiology of disc edema.

Methods:

We measured average retinal nerve fiber layer (RNFL) thickness and the retinal pigment epithelium/Bruch’s membrane (RPE/BM) angle at the temporal and nasal borders of the neural canal opening (NCO) in 30 eyes with papilledema, 30 eyes with papillitis, and 80 control eyes. The inward angulation was considered as positive and the outward as negative. Follow-up was done at 1, 2, 3, and 6 months. The main outcome measures are the average RNFL thickness and the RPE/BM angle.

Results:

29 eyes (96.6%) with papilledema had a positive RPE/BM angle (+8.11 ± 3.13). 29 eyes (96.6%) with papillitis had a negative RPE/BM angle (−1.04 ± 3.27). On follow-up at 1 month, both RNFL thickness (P = 0.01) and RPE-BM angle (P = 0.001) reduced significantly in eyes with papilledema; in eyes with papillitis, there was a significant reduction in the RNFL thickness (P = 0.02), but not in the RPE-BM angle (P > 0.05). RNFL thickness in papilledema cases normalized at 3 months whereas RPE/BM normalized at 6 months of follow-up. To detect papilledema, OCT has a sensitivity of 96.66% and specificity of 99.09% on both nasal and temporal sides.

Conclusion:

After appropriate treatment, the RPE/BM angle in papilledema decreased much later than the RNFL thickness. Hence, the RPE/BM angle in papilledema (positive) can be used to differentiate it from papillitis (negative) and also to monitor the activity of the disease.

Updates on ophthalmic imaging features of optic disc drusen, papilledema, and optic disc edema

Purpose of review

Optic nerve head elevation can be associated with vision loss. This review provides an update regarding key features of optic disc drusen (ODD) compared with papilledema from increased intracranial pressure and optic disc edema from other causes.

Recent findings

Clinical history and funduscopic examination are not sufficient to correctly diagnose different causes of optic nerve head elevation. Multimodal ophthalmic imaging is noninvasive and should be used as first-line diagnostic testing to distinguish optic disc edema or papilledema from pseudoedema. Advanced ophthalmic imaging, including enhanced depth imaging optical coherence tomography (EDI-OCT) and autofluorescence imaging, can visualize ODD at high resolution and determine whether there is optic disc edema. OCT angiography does not require contrast and can rapidly visualize papillary, peripapillary, and macular microvasculature and identify important vascular biomarker of ischemia and, potentially, visual prognosis.

Summary

Multimodal ophthalmic imaging can help in the diagnosis of ODD and optic disc edema and identify patients at high risk of vision loss and neurological issues in order to ensure appropriate diagnosis and treatment.

QUANTITATIVE TOPOGRAPHIC CURVATURE MAPS OF THE POSTERIOR EYE UTILIZING OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

Deformations of the retina such as staphylomas in myopia or scleral flattening in high intracranial pressure can be challenging to quantify with en face imaging. We describe an optical coherence tomography-based method for the generation of quantitative posterior eye topography maps in normal and pathologic eyes.

METHODS

Using "whole eye" optical coherence tomography, we corrected for subjects' optical distortions to generate spatially accurate posterior eye optical coherence tomography volumes and created local curvature (KM, mm-1) topography maps for each consented subject. We imaged nine subjects, three normal, two with myopic degeneration, and four with papilledema including one that was imaged longitudinally.

RESULTS

Normal subjects mean temporal KM was 0.0923 mm-1, nasal KM was 0.0927 mm-1, and KM local variability was 0.0162 mm-1. In myopic degeneration, subjects KM local variability was higher at 0.0836 mm-1. In papilledema subjects nasal KM was flatter compared with temporal KM (0.0709 vs. 0.0885 mm-1). Mean intrasession KM repeatability for all subjects was 0.0036 mm-1.

CONCLUSION

We have developed an optical coherence tomography based method for quantitative posterior eye topography that offers the ability to analyze local curvature with micron scale resolution and offers the potential to help clinicians and researchers characterize subtle, local retinal deformations earlier in patients and follow their development over time.

Optical Coherence Tomography Neuro-Toolbox for the Diagnosis and Management of Papilledema, Optic Disc Edema, and Pseudopapilledema

BACKGROUND

Distinguishing optic disc edema from pseudopapilledema is a common, sometimes challenging clinical problem. Advances in spectral-domain optical coherence tomography (SD-OCT) of the optic nerve head (ONH) has proven to be a cost effective, noninvasive, outpatient procedure that may help. At its core are tools that quantify the thickness of the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL). The SD-OCT also provides a set of tools that may be qualitatively interpreted in the same way that we read an MRI. They include the transverse axial, en face, and circular tomogram. Our goal is to describe a practical office-based set of tools using SD-OCT in the diagnosis and monitoring of papilledema, optic disc edema, and pseudopapilledema.

EVIDENCE ACQUISITION

Searches on PubMed were performed using combinations of the following key words: OCT, papilledema, pseudopapilledema, optic disc drusen, retinal folds (RF), and choroidal folds (CF).

RESULTS

The principal elements of SD-OCT analysis of the ONH are the RNFL and GC-IPL thickness; however, these metrics have limitations when swelling is severe. Qualitative interpretation of the transverse axial SD-OCT aids in assessing peripapillary shape that may help distinguish papilledema from pseudopapilledema, evaluate atypical optic neuropathies, diagnose shunt failures, and identify outer RF and CF. There is a consensus that the SD-OCT is the most sensitive way of identifying buried optic disc drusen. En face SD-OCT is especially effective at detecting peripapillary wrinkles and outer retinal creases, both of which are common and distinctive signs of optic disc edema that rule out pseudopapilledema. Mechanically stressing the ONH in the adducted eye position, in patients with papilledema, may expose folds and peripapillary deformations that may not be evident in primary position. We also discuss how to optimize the acquisition and registration of SD-OCT images.

CONCLUSIONS

The SD-OCT is not a substitute for a complete history and a careful examination. It is, however, a convenient ancillary test that aids in the diagnosis and management of papilledema, optic disc edema, and pseudopapilledema. It is particularly helpful in monitoring changes over the course of time and distinguishing low-grade papilledema from buried drusen. The application of the SD-OCT toolbox depends on optimizing the acquisition of images, understanding its limitations, recognizing common artifacts, and accurately interpreting images in the context of both history and clinical findings.

Utility of spectral domain OCT in differentiating optic disc drusen from papilledema in children

OBJECTIVE

The purpose of this study was to test the diagnostic accuracy of optical coherence tomography (OCT) in differentiating optic disc drusen (ODD) from papilledema in children.

DESIGN

Retrospective cross-sectional study at a tertiary-care pediatric hospital.

PARTICIPANTS

Children with high-quality OCT imaging of ODD or papilledema.

METHODS

Quantitative OCT parameters and qualitative OCT features were compared for diagnostic accuracy.

RESULTS

There were 41 eyes with ODD and 21 eyes with papilledema. Both the quantitative and qualitative OCT parameters showed highly statistically significant differences between ODD and papilledema (p ≤ 0.01 for all). For quantitative parameters (Bruch's membrane opening and retinal nerve fiber layer thicknesses), the area under the curve from the receiver operator curves ranged from 0.81 to 0.90. For qualitative parameters, the sensitivity for ODD ranged from 27% to 100% and specificity ranged from 67% to 100%. The presence of at least 1 of 3 qualitative OCT parameters (hyporeflective boot-shaped area, isolated/clustered hyperreflective bands, or signal-poor regions in the core) had a sensitivity of 90% and a specificity of 100% for ODD.

CONCLUSIONS

Both quantitative and qualitative OCT parameters differed significantly between ODD and papilledema in this cohort of children. A combination of several qualitative OCT features had high sensitivity for ODD while effectively ruling out papilledema.

Optical coherence tomography (OCT) in neuro-ophthalmology

Optical coherence tomography (OCT) is a non-invasive medical imaging technology that is playing an increasing role in the routine assessment and management of patients with neuro-ophthalmic conditions. Its ability to characterise the optic nerve head, peripapillary retinal nerve fibre layer and cellular layers of the macula including the ganglion cell layer enables qualitative and quantitative assessment of optic nerve disease. In this review, we discuss technical features of OCT and OCT-based imaging techniques in the neuro-ophthalmic context, potential pitfalls to be aware of, and specific applications in more common neuro-ophthalmic conditions including demyelinating, inflammatory, ischaemic and compressive optic neuropathies, optic disc drusen and raised intracranial pressure. We also review emerging applications of OCT angiography within neuro-ophthalmology.

Recent advances and future directions on the use of optical coherence tomography in neuro-ophthalmology

Optical coherence tomography (OCT) is a noninvasive imaging technique used to qualitatively and quantitatively analyze various layers of the retina. OCT of the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) is particularly useful in neuro-ophthalmology for the evaluation of patients with optic neuropathies and retrochiasmal visual pathway disorders. OCT allows for an objective quantification of edema and atrophy of the RNFL and GCIPL, which may be evident before obvious clinical signs and visual dysfunction develop. Enhanced depth imaging OCT allows for visualization of deep structures of the optic nerve and has emerged as the gold standard for the detection of optic disc drusen. In the evaluation of compressive optic neuropathies, OCT RNFL and GCIPL thicknesses have been established as the most important visual prognostic factor. There is increasing evidence that inclusion of OCT as part of the diagnostic criteria for multiple sclerosis (MS) increases its sensitivity. Moreover, OCT of the RNFL and GCIPL may be helpful in the early detection and monitoring the treatment of conditions such as MS and Alzheimer's disease. OCT is an important aspect of the neuro-ophthalmologic assessment and its use is likely to increase moving forward.

The Effects of Acute Intracranial Pressure Changes on the Episcleral Venous Pressure, Retinal Vein Diameter and Intraocular Pressure in a Pig Model

PURPOSE

Orbital veins such as the retinal veins and episcleral veins drain into the cavernous sinus, an intracranial venous structure. We studied the effects of acute intracranial pressure (ICP) elevation on episcleral venous pressure, intraocular pressure and retinal vein diameter in an established non-survival pig model.

METHODS

In six adult female domestic pigs, we increased ICP in 5 mm Hg increments using saline infusion through a lumbar drain. We measured ICP (using parenchymal pressure monitor), intraocular pressure (using pneumatonometer), episcleral venous pressure (using venomanometer), retinal vein diameter (using OCT images) and arterial blood pressure at each stable ICP increment. The average baseline ICP was 5.4 mm Hg (range 1.5-9 mm Hg) and the maximum stable ICP ranged from 18 to 40 mm Hg. Linear mixed models with random intercepts were used to evaluate the effect of acute ICP increase on outcome variables.

RESULTS

With acute ICP elevation, we found loss of retinal venous pulsation and increased episcleral venous pressure, intraocular pressure and retinal vein pressure in all animals. Specifically, acute ICP increase was significantly associated with episcleral venous pressure (β = 0.31; 95% CI 0.14-0.48, p < .001), intraocular pressure (β = 0.37, 95%CI 0.24-0.50; p < .001) and retinal vein diameter (β = 11.29, 95%CI 1.57-21.00; p = .03) after controlling for the effects of arterial blood pressure.

CONCLUSION

We believe that the ophthalmic effects of acute ICP elevation are mediated by increased intracranial venous pressure producing upstream pressure changes within the orbital and retinal veins. These results offer exciting possibilities for the development of non-invasive ophthalmic biomarkers to estimate acute ICP elevations following significant neuro-trauma.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

Measurement of intracranial pressure (ICP) is crucial in the management of many neurological conditions. However, due to the invasiveness, high cost, and required expertise of available ICP monitoring techniques, many patients who could benefit from ICP monitoring do not receive it. As a result, there has been a substantial effort to explore and develop novel noninvasive ICP monitoring techniques to improve the overall clinical care of patients who may be suffering from ICP disorders. This review attempts to summarize the general pathophysiology of ICP, discuss the importance and current state of ICP monitoring, and describe the many methods that have been proposed for noninvasive ICP monitoring. These noninvasive methods can be broken down into four major categories: fluid dynamic, otic, ophthalmic, and electrophysiologic. Each category is discussed in detail along with its associated techniques and their advantages, disadvantages, and reported accuracy. A particular emphasis in this review will be dedicated to methods based on the use of transcranial Doppler ultrasound. At present, it appears that the available noninvasive methods are either not sufficiently accurate, reliable, or robust enough for widespread clinical adoption or require additional independent validation. However, several methods appear promising and through additional study and clinical validation, could eventually make their way into clinical practice.

An Update on Imaging in Idiopathic Intracranial Hypertension

Neuroimaging plays an essential role in the diagnostic workup of idiopathic intracranial hypertension with the aims to exclude secondary causes of elevated intracranial pressure and to identify imaging signs that are commonly observed in this disorder. As a valuable expansion of brain imaging, the imaging of the retina using optical coherence tomography has been of increasing value. In particular, this is the case with the latest devices that allow a more accurate distinction between a reduction in retinal nerve fiber layer thickness due to an improvement of papilledema or due to a worsening caused by optic nerve atrophy. Although optical coherence tomography does not yet replace the other elements of the diagnostic workup, it is likely to play an increasing role in diagnosis and follow-up of idiopathic intracranial hypertension. The review focuses on the main findings in neuroimaging, including structural and vascular alterations as well as on the relevance of optical coherence tomography.

Imaging Methods for Differentiating Pediatric Papilledema from Pseudopapilledema: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature on the accuracy of ophthalmic imaging methods to differentiate between papilledema and pseudopapilledema in children.

METHODS

Literature searches were conducted in January 2020 in the PubMed database for English-language studies with no date restrictions and in the Cochrane Library database without any restrictions. The combined searches yielded 354 abstracts, of which 17 were reviewed in full text. Six of these were considered appropriate for inclusion in this assessment and were assigned a level of evidence rating by the panel methodologist. All 6 included studies were rated as level III evidence.

RESULTS

Fluorescein angiography, a combination of 2 OCT protocols, and multicolor confocal scanning laser ophthalmoscopy (Spectralis SD-OCT; Heidelberg Engineering, Heidelberg, Germany) demonstrated the highest positive percent agreement (92%-100%; 95% confidence interval [CI], 69%-100%) and negative percent agreement (92%-100%; 95% CI, 70%-100%) with a clinical diagnosis of papilledema in children. However, results must be interpreted with caution owing to methodologic limitations, including a small sample size leading to wide CIs and an overall lack of data (there was only 1 study each for the above methods and protocols). Ultrasonographic measures showed either a high positive percent agreement (up to 95%) with low negative percent agreement (as low as 58%) or vice versa. Autofluorescence and fundus photography showed a lower positive (40%-60%) and negative (57%) percent agreement.

CONCLUSIONS

Although several imaging methods demonstrated high positive and negative percent agreement with clinical diagnosis, no ophthalmic imaging method conclusively differentiated papilledema from pseudopapilledema in children because of the lack of high-quality evidence. Clinicians must continue to conduct thorough history-taking and examination and make judicious use of ancillary testing to determine which children warrant further workup for papilledema.

The Effect of Acetazolamide and Weight Loss on Intraocular Pressure in Idiopathic Intracranial Hypertension Patients

PURPOSE

Acetazolamide (ACZ) lowers intraocular pressure (IOP), acutely in normal eyes and both acutely and chronically in eyes with glaucoma, and cerebrospinal fluid pressure (CSFp), chronically in patients with idiopathic intracranial hypertension (IIH). We hypothesize chronic daily ACZ would significantly reduce IOP and contribute to a translaminar pressure gradient change reflected by alteration in the CSFp-IOP difference and the deformation of the neural canal in patients with IIH and no glaucoma.

PATIENTS AND METHODS

Before randomization to ACZ or placebo treatment for 6 months, 165 participants in the IIH Treatment Trial had evaluations that included Goldmann applanation, CSFp measurement, and optical coherence tomography determination of the neural canal deformation. These measures were repeated at the 6-month outcome.

RESULTS

The IOP was not significantly decreased from baseline at 1, 3, or 6 months in eyes in both treatment groups. At month 6, the amount of ACZ or weight modification did not correlate with any IOP change. The 6-month mean change in neural canal deformation was 0.96 and -0.04 (P=0.001) and in CSFp was -128 and -38 mm H2O (P=0.001), but CSFp-IOP difference change was not significant, in the ACZ and placebo groups, respectively.

CONCLUSIONS

ACZ does not reduce the IOP in eyes without glaucoma but does decrease the pathologic elevated CSFp, providing evidence that normal systems can compensate for chronic medication effects. The CSFp-IOP is not a direct marker of translaminar pressure gradient and the ACZ normalization of the neural canal deformation appears due to CSFp reduction alone.

The Optic Disc Drusen Studies Consortium Recommendations for Diagnosis of Optic Disc Drusen Using Optical Coherence Tomography

BACKGROUND

Making an accurate diagnosis of optic disc drusen (ODD) is important as part of the work-up for possible life-threatening optic disc edema. It also is important to follow the slowly progressive visual field defects many patients with ODD experience. The introduction of enhanced depth imaging optical coherence tomography (EDI-OCT) has improved the visualization of more deeply buried ODD. There is, however, no consensus regarding the diagnosis of ODD using OCT. The purpose of this study was to develop a consensus recommendation for diagnosing ODD using OCT.

METHODS

The members of the Optic Disc Drusen Studies (ODDS) Consortium are either fellowship trained neuro-ophthalmologists with an interest in ODD, or researchers with an interest in ODD. Four standardization steps were performed by the consortium members with a focus on both image acquisition and diagnosis of ODD.

RESULTS

Based on prior knowledge and experiences from the standardization steps, the ODDS Consortium reached a consensus regarding OCT acquisition and diagnosis of ODD. The recommendations from the ODDS Consortium include scanning protocol, data selection, data analysis, and nomenclature.

CONCLUSIONS

The ODDS Consortium recommendations are important in the process of establishing a reliable and consistent diagnosis of ODD using OCT for both clinicians and researchers.

Optical coherence tomography use in idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a condition in which elevated pressure in the cerebrospinal fluid can lead to optic nerve head (ONH) dysfunction and subsequent visual impairment. Physicians are currently limited in their ability to monitor and manage this condition, as clinical symptoms and exam findings are often delayed in response to changes in intracranial pressure. In order to find other biomarkers of disease, researchers are using imaging modalities such as optical coherence tomography (OCT) to observe microscopic changes in the eye in this condition. OCT can create 2-dimensional and 3-dimensional high definition images of the retina of the ONH and has been used to study various conditions such as glaucoma and multiple sclerosis. Numerous studies have used OCT in IIH as well, and they have shown that certain retinal layers and the ONH change in thickness and shape in both the short and long term with intracranial pressure changes. OCT is a promising modality for clinical and scientific evaluation of IIH as it is a noninvasive and practical tool to obtain in depth images. This review will discuss how OCT can be used to assess a patient with IIH, both before and after treatment, along with its limitations and future applications.

Custom Optical Coherence Tomography Parameters for Distinguishing Papilledema from Pseudopapilledema

SIGNIFICANCE

Causes of papilledema can be life-threatening; however, distinguishing papilledema from pseudopapilledema is often challenging. The conventional optical coherence tomography (OCT) scan for assessing the optic nerve often fails to detect mild papilledema. Our study suggests that parameters derived from volumetric OCT scans can provide additional useful information for detecting papilledema.

PURPOSE

Optical coherence tomography analysis of the optic nerve commonly measures retinal nerve fiber layer thickness (RNFLT) along a 1.73-mm-radius scan path. This conventional scan, however, often fails to detect mild papilledema. The purpose of this study was to evaluate additional OCT-derived measures of the optic nerve head (ONH) and peripapillary retina for differentiating papilledema (all grades and mild) from pseudopapilledema.

METHODS

Cirrus OCT ONH volume scans were acquired from 21 papilledema (15 mild papilledema), 27 pseudopapilledema, and 42 control subjects. Raw scan data were exported, and total retinal thickness within Bruch's membrane opening (BMO) plus RNFLT and total retinal thickness at the following eccentricities were calculated using custom algorithms: BMO to 250, 250 to 500, 500 to 1000, and 1000 to 1500 μm. Minimum rim width was calculated, and BMO height was measured from a 4-mm Bruch's membrane reference plane centered on the BMO.

RESULTS

Retinal nerve fiber layer thickness from BMO to 250 μm, minimum rim width, and BMO height had significantly greater areas under the receiver operating characteristic curve than did conventional RNFLT for differentiating mild papilledema from pseudopapilledema (P < .0001) and greater sensitivities at 95% specificity. Using cutoff values at 95% specificity, custom parameters detected 10 mild papilledema patients, and conventional RNFLT detected only 1. Bruch's membrane opening heights above the reference plane were observed in papilledema only, although many papilledema cases had a neutral or negative BMO height.

CONCLUSIONS

Using OCT volumetric data, additional parameters describing peripapillary tissue thickness, neuroretinal rim thickness, and ONH position can be calculated and provide valuable measures for differentiating mild papilledema from pseudopapilledema.

An Ultrasound Vibro-Elastography Technique for Assessing Papilledema

Papilledemais optic nerve swelling caused by increased intracranial hypertension, which has the potential to cause significant vision loss. Papilledema from idiopathic intracranial hypertension (IIH) is typically bilateral and symmetric, but can be asymmetric and even unilateral. The purpose of this study was to develop ultrasound vibro-elastography (UVE) for non-invasive measurement of ocular tissue wave speed for patients with papilledema. A total of 9 patients with papilledema from IIH and 9 age-matched healthy control patients were enrolled in this study. A local, gentle, 0.1-s harmonic vibration was applied on the eyelid to generate wave propagation in the ocular tissue. We used 3 excitation frequencies of 100, 150 and 200 Hz to measure the wave speeds. A 6.4-MHz ultrasound probe was used to non-invasively measure wave propagation in the ocular structures. Wave speeds were analyzed in the posterior sclera of the maculae of the eyes. The magnitudes of wave speed at each frequency of the IIH patients' posterior sclera were significantly higher than those of healthy patients. It was found that the magnitudes of wave speed at each frequency were statistically higher in the eyes with papilledema than in the contralateral eyes without papilledema for the patients with unilateral papilledema. UVE provides a non-invasive technique to measure the wave speed of posterior sclera, which may be useful for assessing patients with papilledema.

Methods for Quantifying Optic Disc Volume and Peripapillary Deflection Volume Using Radial Optical Coherence Tomography Scans and Association With Intracranial Pressure

Purpose: Papilledema and peripapillary deformation of Bruch's membrane (BM) are associated with elevated intracranial pressure (ICP). We have developed a novel methodology to measure these parameters using a radial optical coherence tomography (OCT) scan pattern and apply this to test the hypothesis that ICP is associated with volumetric features of ophthalmic structures.

Methods: 6-radial OCT B-scans centered over the optic nerve head were acquired in 17 subjects (30 eyes) before lumbar puncture with measurement of ICP (range: 10–55 cm H₂O). Internal limiting membrane (ILM) and BM were segmented. Three definitions of BM were studied to account for imaging artifact affecting peripapillary BM: connecting rater-identified BM margins(traditional), connecting rater-identified BM 1.6 mm on either side of the ONH(estimated), and excluding BM in the central 3.2 mm of the images(excluded). Optic nerve head volume (ONHV), BM displacement volume (BMDV) and cup volume (CV) were calculated by interpolating between B-scans. Ganglion cell complex volume (GCCV) was measured in the macula. Linear generalized estimating equations (GEE) modeled ONVH, BMDV, and CV as a function of ICP and GCCV.

Results: Increased ONHV was associated with elevated ICP for traditional (p = 0.006), estimated (p = 0.003) and excluded (p = 0.05) BM definitions. Decreased BMDV was associated with elevated ICP for traditional (p < 0.0005), estimated (p < 0.0005) and excluded (p = 0.001) definitions. Decreased ONHV was independently associated with decreased GCCV (p = 0.001) and decreased ICP (p = 0.031) in multivariable models. CV was neither associated with ICP nor GCCV in univariate or multivariable models.

Conclusions: Elevated ICP is associated with ONHV increase and BMDV decrease, calculated from OCT images accounting for image artifact. Ganglion cell atrophy affects the relationship between ICP and ONHV. OCT derived volumetric measures of the posterior eye may have application as biomarkers for elevated ICP.

Don't Miss This! Red Flags in the Pediatric Eye Exam: Blurred Disc Margins

Evaluating a patient with blurred optic disc margins, particularly a child, and establishing a diagnosis can be a demanding task. We aim to review the differential diagnosis of blurred disc margins, identify the clinical characteristics of a swollen optic disc, discuss imaging modalities used in the evaluation of the optic nerve head as tools for formulating a diagnosis, and identify red flags that may indicate a serious disorder.

Factors Influencing Central Lamina Cribrosa Depth: A Multicenter Study

Purpose

To quantify the influence of ocular and demographic factors on central laminar depth (LD) in healthy participants.

Methods

A total of 362 normal subjects underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head (ONH) with a 24 radial B-scan pattern aligned to the fovea–to–Bruch's membrane opening (BMO) axis. BMO, anterior lamina, anterior scleral canal opening (ASCO), Bruch's membrane (BM), and the peripapillary scleral surface were manually segmented. The extent of laminar segmentation was quantified within 72 ASCO subsectors. Central LD was quantified relative to four reference planes: BMO, ASCO, BM, and scleral. The effects of age, sex, ethnicity, IOP, BMO area, ASCO area, and axial length on LD were assessed.

Results

Laminar visibility was most consistent within the central ASCO (median 89%, range, 69%–95%). LD_BMO and LD_BM were significantly shallower in eyes with greater age, BMO area, and axial length and in females. LD_ASCO was shallower in eyes with greater ASCO area and axial length and in European and Hispanic descent compared to African descent eyes. LD_Sclera behaved similarly, but was not associated with axial length. BMO and ASCO area were not different between African descent and European descent eyes.

Conclusions

Central LD was deeper in African descent eyes and influenced least by age, axial length, and sex, but more by ASCO area, when measured relative to the ASCO and sclera. However, the magnitude of these effects for all four reference planes was small, and their clinical importance in the detection of glaucoma and its progression remains to be determined.

The Role of Optical Coherence Tomography in Differentiating Optic Disc Drusen from Optic Disc Edema

An elevated optic nerve head can be an ominous sign, sometimes signifying an underlying basis for raised intracranial pressure. Alternatively, patients may harbor a different mechanism for this optic nerve head appearance, including optic disc drusen (ODD), which does not confer any life-threatening implications. It is important to refine the approach to distinguishing ODD from papilledema because this is a relatively common, and important, conundrum encountered in clinical practice. Optical coherence tomography (OCT) is a noninvasive, readily accessible, and cost-effective ocular imaging technique that can improve the diagnostic accuracy for detecting ODD; or, instead, increase the index of suspicion for papilledema, thus prompting additional investigations needed to identify (or exclude) potential causes of raised intracranial pressure. In this review, we will discuss the value of OCT in the diagnostic approach to cases of mild optic disc elevation, with acknowledgment of the potential pearls and pitfalls of this imaging technology. In particular, we will emphasize the helpful role OCT can play in differentiating cases of ODD from mild papilledema in the context of idiopathic intracranial hypertension (IIH).

Bruch's membrane opening on optical coherence tomography in pediatric papilledema and pseudopapilledema

PURPOSE

To determine whether the diameter of Bruch's membrane opening (BMO) can distinguish mild papilledema from pseudopapilledema using optical coherence tomography (OCT).

METHODS

The medical records of pediatric patients with pseudopapilledma due to optic nerve head (ONH) drusen, patients with papilledema, and normal control subjects were retrospectively reviewed. All eyes underwent OCT imaging of the BMO and retinal nerve fiber layer (RNFL). Transverse horizontal diameter of the BMO and papillary height were measured. Mean BMO, papillary height, and RNFL were compared and receiver operating characteristic (ROC) curves were used to calculate the area under the curve (AUC) and determine BMO and RNFL cut-offs for papilledema and pseudopapilledema.

RESULTS

A total of 90 eyes of 90 subjects were included: 58 with pseudopapilledema, 19 with papilledema, and 13 controls. In eyes with papilledema, mean BMO, papillary height, and RNFL decreased as papilledema resolved (1893.8 vs 1582.2 [P = 0.0003], 193.0 vs 108.9 [P < 0.0001], 893.3 vs 695.5 [P = 0.0007], resp.). Eyes with mild papilledema had greater mean BMO and RNFL than those with pseudopapilledema and controls (1893.8 vs 1541.9 vs 1628.8 [P < 0.0001, P = 0.0265] and 193.0 vs 108.7 vs 104.1 [P < 0.0001, P < 0.0001], resp.). Papillary height in mild papilledema was similar to pseudopapilledema but greater than controls (893.3 vs 863.2 vs 593.5 [P = 0.47 and P = 0.0001], resp.). ROC showed good diagnostic discrimination for BMO (AUC = 0.81; 95% CI, 0.70-0.92) and RNFL (AUC = 0.96; 95% CI, 0.93-1.0) in distinguishing mild papilledema from pseudopapilledema.

CONCLUSIONS

The horizontal transverse diameter of BMO is enlarged in eyes with mild papilledema and narrows as papilledema resolves. BMO and RNFL can be used together to help distinguish mild papilledema from pseudopapilledema in children.

Spaceflight-Induced Intracranial Hypertension and Visual Impairment: Pathophysiology and Countermeasures

Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained major risk for future long-duration spaceflight. NASA recently redefined this syndrome as Spaceflight-Associated Neuro-ocular Syndrome (SANS). Evidence thus reviewed supports that chronic, mildly elevated intracranial pressure (ICP) in space (as opposed to more variable ICP with posture and activity on Earth) is largely accounted for by loss of hydrostatic pressures and altered hemodynamics in the intracranial circulation and the cerebrospinal fluid system. In space, an elevated pressure gradient across the lamina cribrosa, caused by a chronic but mildly elevated ICP, likely elicits adaptations of multiple structures and fluid systems in the eye which manifest themselves as the VIIP syndrome. A chronic mismatch between ICP and intraocular pressure (IOP) in space may acclimate the optic nerve head, lamina cribrosa, and optic nerve subarachnoid space to a condition that is maladaptive to Earth, all contributing to the pathogenesis of space VIIP syndrome. Relevant findings help to evaluate whether artificial gravity is an appropriate countermeasure to prevent this seemingly adverse effect of long-duration spaceflight.

Accuracy of Diagnostic Imaging Modalities for Classifying Pediatric Eyes as Papilledema Versus Pseudopapilledema

PURPOSE

To identify the most accurate diagnostic imaging modality for classifying pediatric eyes as papilledema (PE) or pseudopapilledema (PPE).

DESIGN

Prospective observational study.

SUBJECTS

Nineteen children between the ages of 5 and 18 years were recruited. Five children (10 eyes) with PE, 11 children (19 eyes) with PPE owing to suspected buried optic disc drusen (ODD), and 3 children (6 eyes) with PPE owing to superficial ODD were included.

METHODS

All subjects underwent imaging with B-scan ultrasonography, fundus photography, autofluorescence, fluorescein angiography (FA), optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL), and volumetric OCT scans through the optic nerve head with standard spectral-domain (SD OCT) and enhanced depth imaging (EDI OCT) settings. Images were read by 3 masked neuro-ophthalmologists, and the final image interpretation was based on 2 of 3 reads. Image interpretations were compared with clinical diagnosis to calculate accuracy and misinterpretation rates of each imaging modality.

MAIN OUTCOME MEASURES

Accuracy of each imaging technique for classifying eyes as PE or PPE, and misinterpretation rates of each imaging modality for PE and PPE.

RESULTS

Fluorescein angiography had the highest accuracy (97%, 34 of 35 eyes, 95% confidence interval 92%-100%) for classifying an eye as PE or PPE. FA of eyes with PE showed leakage of the optic nerve, whereas eyes with suspected buried ODD demonstrated no hyperfluorescence, and eyes with superficial ODD showed nodular staining. Other modalities had substantial likelihood (30%-70%) of misinterpretation of PE as PPE.

CONCLUSIONS

The best imaging technique for correctly classifying pediatric eyes as PPE or PE is FA. Other imaging modalities, if used in isolation, are more likely to lead to misinterpretation of PE as PPE, which could potentially result in failure to identify a life-threatening disorder causing elevated intracranial pressure and papilledema.

Pediatric Pseudotumor Cerebri Syndrome

Idiopathic intracranial hypertension, otherwise known as primary pseudotumor cerebri syndrome (PTCS), most frequently occurs in obese women of childbearing age. However, children may be affected as well. This review will address recent findings regarding demographics, diagnosis, and treatment of pediatric PTCS. Prepubertal children with primary PTCS have an equal sex distribution and less frequent obesity compared with adult patients. However, female gender and obesity are risk factors for primary PTCS in postpubertal children. Compared with adults, children with PTCS more frequently present with ocular motility deficits and more often have associated medical conditions that increase the risk of developing PTCS. Visual field testing may be unreliable, and the optimal modality to monitor visual function is unknown. MRI shows signs of elevated intracranial pressure (ICP) in children with PTCS similar to that of adults. It has now been established that elevated ICP in children ≤18 years old is greater than 25 cm H20 in nonobese, nonsedated children, and greater than 28 cm H2O in the remainder. Optical coherence tomography (OCT) may be used to distinguish pseudopapilledema from papilledema, monitor response to treatment in preverbal children, and identify patients with PTCS at risk for permanent visual loss. However, the precise role of OCT in the management of pediatric PTCS remains to be determined.