Effects of lowering cerebrospinal fluid pressure on the shape of the peripapillary retina in intracranial hypertension

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.

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.

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.

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.

The association of cerebrospinal fluid pressure with optic nerve head and macular vessel density

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure (CSFP) reduction on optic nerve head (ONH) and macular vessel density (VD) using optical coherence tomography angiography. Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited. Thirty-two eyes of 32 healthy volunteers were controls. ONH and macular VD images were evaluated differences between baseline and after CSFP reduction. The results showed that the mean CSFP decreased from (11.6±2.1) mmHg to (8.2±3.4) mmHg (P<0.001). VD in the macular regions decreased significantly after CSFP reduction in the study group (all P<0.05). The control group showed no significant changes in macular VD (all P>0.05). In the study group, decreased VD in the macular parainferior region was associated with CSFP reduction (R²=0.192, P=0.003), the reduction of macular VD in parafoveal (R²=0.098, P=0.018), parainferior (R²=0.104, P=0.021), parasuperior (R²=0.059, P=0.058), paranasal (R²=0.057, P=0.042), paratemporal (R²=0.079, P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction. ONH vessel density did not differ after CSFP reduction (all P>0.05). In conclusion, macular vessel density decreased in association with CSFP reduction. Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.

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.

The Association of Acute Cerebrospinal Fluid Pressure Reduction with Choroidal Thickness

PURPOSE

To investigate the changes in choroidal thickness (CT) after acute cerebrospinal fluid pressure (CSFP) reduction in human subjects.

METHODS

Before and 15 minutes after diagnostic lumbar puncture (LP), 44 patients underwent measurement of CT by swept-source optical coherence tomography. Thirty-two healthy volunteers imitated the body posture of LP procedure and underwent the same measurement before and 15 minutes after body posture change.

RESULTS

After CSFP reduction from 10.9 ± 2.1 mmHg at baseline to 8.1 ± 1.5 mmHg (p < 0.001), CT decreased in subfoveal region (p = 0.005), small to medium vessel layer (SMVL, p < 0.001), peripapillary regions in temporal (p = 0.001), nasal (p < 0.001), superior (p < 0.001) and inferior (p < 0.001), respectively. However, no significant change in CT in the control group after body posture change (all p > 0.05). A significant association between CSFP and the ratio of small to medium vessel layer to total choroidal thickness was found (p = 0.009). The CSFP reduction rate was associated with the change rate of SMVL to total CT portion, for each percent decrease in CSFP was associated with a decrease by 0.22% in the rate of SMVL to total CT portion (R² = 0.125, p = 0.018).

CONCLUSIONS

A significant decrease in subfoveal CT, small to medium vessel layer and peripapillary region were observed following acute CSFP reduction. The CSFP reduction rate was associated with the change rate of small to medium vessel layer to total CT portion.

A novel biomarker for increased intracranial pressure in idiopathic intracranial hypertension

PURPOSE

Changes in optic disc and peripapillary structures associated with optic nerve edema in idiopathic intracranial hypertension (IIH), can be evaluated with spectral domain optical coherence tomography (SD-OCT). We aimed to evaluate the association between increased cerebrospinal fluid (CSF) opening pressure and changes in peripapillary structures detected by SD-OCT and to determine whether these changes can be used to assess the changes in CSF pressure without performing lumbar puncture (LP).

STUDY DESIGN

Retrospective study METHODS: We included 54 eyes of 28 patients with bilateral papilledema who had peripapillary SD-OCT imaging within 24 h before the LP. Correlation between CSF pressure and peripapillary OCT parameters including maximal retinal thickness, maximal anterior retinal projection, maximal retinal nerve fiber layer (RNFL) thickness and Bruch membrane opening (BMO) was evaluated.

RESULTS

Bruch Membrane opening and maximal RNFL thickness were significantly higher in patients with increased CSF pressure. There exist correlations between CSF pressure and BMO, maximal RNFL thickness and maximal retinal thickness. (Spearman's Rho: 0.791, 0.482 and 0.297, p < 0.001, < 0.001 and 0.029, respectively) The cut off value of BMO for the prediction of increased CSF pressure was 1785 µm, with a sensitivity of 78.8% and a specificity of 81%. The cut off value for maximal RNFL thickness was 174 µm, with a sensitivity of 75.8% and a specificity of 61.9%.

CONCLUSION

Bruch membrane opening and maximal RNFL thickness can give an idea about increased CSF pressure values in IIH patients. Thus SD-OCT can be used to detect CSF pressure changes in these patients.

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.

Morphological assessment of lamina cribrosa in idiopathic intracranial hypertension

Purpose:

Technological development of optic coherence tomography has enabled a detailed assessment of the optic nerve and deeper structures and in vivo measurements. The aim of this study was to compare the lamina cribrosa morphology of the optic nerve in idiopathic intracranial hypertension (IIH) and healthy individuals.

Methods:

The lamina cribrosa morphology of optic nerve in 15 eyes with IIH and 17 eyes of healthy individuals were compared. Four parameters such as Bruch membrane opening (BMO), lamina cribrosa thickness (LCT), prelaminar tissue thickness (PTT), and anterior lamina cribrosa surface depth (ALCSD) were retrospectively evaluated.

Results:

By enhanced depth imaging-optic coherence tomography (EDI-OCT), PTT and BMO were found to be significantly greater (574,35 ± 169,20 μm and 1787,40 ± 140,87 μm, respectively) in IIH patients than healthy individuals (187,18 ± 132,15 μm and 1632,65 ± 162,58 μm, respectively), whereas ALSCD was found to be significantly less in IIH patients (234,49 ± 49,31 μm) than healthy individuals (425,65 ± 65,23 μm). There was not a statistically significant difference regarding LCT between the IIH patients (238,59 ± 17,31 μm) and healthy individuals (244,96 ± 15,32 μm).

Conclusion:

Increased intracranial pressure causes morphological changes in lamina cribrosa. Assessment of lamina cribrosa with EDI-OCT is important for diagnosis and follow-up of patients with IIH. EDI-OCT is objective, reproducible, and cost-effective assistive imaging tool in IIH patients.

Longitudinal Analysis of Bruch Membrane Opening Morphometry in Myopic Glaucoma

PRéCIS:: The Bruch membrane opening (BMO) was posteriorly bowed and the degree of nonplanarity increased in stable and progressive glaucoma subjects. BMO became more posterior relative to the Bruch membrane (BM) in control and both stable and progressive glaucoma subjects.

PURPOSE

To investigate longitudinal changes in morphologic characteristics of the BMO in control and glaucomatous subjects.

MATERIALS AND METHODS

A total of 53 myopic eyes (17 control, 6 suspect, 20 stable glaucoma, and 10 progressing glaucoma) were followed for an average of 4.2±1.4 years and imaged at the baseline and 2 follow-up appointments using a 1060 nm swept-source optical coherence tomography system. BM and BMO were segmented, and 4 morphometric BMO parameters (area, ellipse ratio, nonplanarity, and depth) were measured.

RESULTS

There were no significant changes in BMO area or ellipse ratio for all groups. BMO nonplanarity was shown to increase in the glaucoma groups. BMO depth relative to BM increased in all groups except the suspects (control: 8.1 µm/y, P=0.0001; stable glaucoma: 3.5 µm/y, P=0.0001; progressing glaucoma: 14.0 µm/y, P=0.0026). In linear mixed-model analysis, axial length was positively associated with BMO area in all groups except for progressing glaucoma, and with BMO nonplanarity in stable glaucoma. It was not a significant factor to the slopes of the BMO parameters in the ANCOVA analysis of slopes.

CONCLUSIONS

Longitudinally, BMO increased in nonplanarity in the glaucoma eyes, and its axial position relative to BM became more posterior in both control and glaucoma eyes.

Optic Nerve Head and Macular Optical Coherence Tomography Measurements in Papilledema Compared With Pseudopapilledema

BACKGROUND

To compare macular and optic nerve head optical coherence tomography (OCT) measurements in mild to moderate papilledema and pseudopapilledema.

METHODS

One hundred nineteen eyes of 61 patients with mild to moderate papilledema, 84 eyes of 48 patients with pseudopapilledema, and 60 eyes of 60 healthy normal individuals were enrolled in this cross-sectional study. Using Spectralis SD-OCT, macular scans with macular ganglion cell-inner plexiform layer (GCIPL) and macular retinal nerve fiber layer (RNFL) segmentation were performed and divided into 2 regions (inner and outer, with a diameter of 3 and 6 mm, respectively); in addition, Bruch membrane opening (BMO) area and peripapillary RNFL thickness were obtained.

RESULTS

BMO area was similar in papilledema (1.83 ± 0.34 mm), pseudopapilledema (1.85 ± 0.37 mm), and controls (1.85 ± 0.32 mm). Average inner region macular GCIPL thickness in the papilledema, pseudopapilledema, and control groups was 87.2 ± 14.4 μm, 90.8 ± 6.1 μm, and 91.2 ± 9.8 μm, respectively (P > 0.05). Outer temporal region macular GCIPL was significantly thinner in the papilledema group compared with control group (P = 0.01). By contrast, outer inferior and outer nasal macular RNFL sectors were significantly thicker in the papilledema group compared with control groups (P = 0.01 and P < 0.01, respectively). Those measures were not different between pseudopapilledema and control eyes.

CONCLUSIONS

In papilledema eyes, outer temporal region macular GCIPL thickness decreased and outer inferior and outer nasal macular RNFL sectors thickness increased compared with the control group. These changes were not observed in the pseudopapilledema group.

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.

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.

Idiopathic Intracranial Hypertension

PURPOSE OF REVIEW

Idiopathic intracranial hypertension is a syndrome of increased intracranial pressure of unclear etiology that most often occurs in obese women of childbearing age but can also occur in men, children, and older adults. This article reviews the diagnostic criteria, clinical features, neuroimaging findings, differential diagnosis, and management options for this condition.

RECENT FINDINGS

Recent population studies have found that the annual incidence of idiopathic intracranial hypertension is increasing in association with obesity rates, whereas recent scientific studies indicate a possible role for androgen sex hormones and adipose tissue in the pathogenesis of the disease. Prospective clinical trials have demonstrated a role for weight loss, acetazolamide, and topiramate in the management of mild disease. A recently begun randomized multicenter trial of surgical interventions will provide insight into the indications for surgical intervention, optimal timing and choice of intervention, and long-term outcomes.

SUMMARY

Idiopathic intracranial hypertension is a disorder producing symptoms and signs of increased intracranial pressure in the absence of an alternative cause. The main goals of treatment are to preserve visual function and alleviate symptoms, which can usually be achieved with a combination of weight loss, medical therapies, and surgical interventions depending on the severity of symptoms and vision loss, response to treatment, and subsequent clinical course.

The effects of negative periocular pressure on intraocular pressure

Glaucoma is a major cause of blindness, and IOP reduction remains the only clinically-validated therapy. In this study, we analyze a novel IOP-lowering strategy that uses a modest negative pressure (vacuum) applied locally to the periorbital region by a pair of goggles with each lens individually connected to a programmable pump. Motivated by clinical data showing an IOP reduction, we used an existing validated lumped-parameter model of the eye to understand the putative mechanism of this treatment. The model considers aqueous humor dynamics, episcleral venous pressure, and changes in ocular blood volume to describe how IOP changes with time in response to an external perturbation. We find that clinical data are qualitatively and quantitatively consistent with model predictions if we include two primary mechanisms in the model: first, negative pressure application causes a relatively rapid increase in globe volume accompanied by increased blood volume in the eye. Second, negative pressure application reduces episcleral venous pressure, causing a slower adjustment of IOP due to altered aqueous humor dynamics. These results provide testable hypotheses that hopefully will lead to a fuller experimentally-driven understanding of how negative periocular pressure influences IOP. Evaluating the long-term effects of such treatments on glaucoma patients requires further clinical study.

Novel advances in monitoring and therapeutic approaches in idiopathic intracranial hypertension

PURPOSE OF REVIEW

The current article appraises the recent developments in idiopathic intracranial hypertension (IIH), with particular attention to novel therapeutic avenues and advanced clinical assessment and monitoring with optical coherence tomography and telemetric intracranial pressure devices.

RECENT FINDINGS

The incidence of IIH is increasing. The first consensus guidelines for IIH have been published detailing investigation and management algorithms for adult IIH. Improved understanding, clinical assessment and monitoring are emerging with the use of optical coherence tomography. Intracranial pressure telemetry is providing unique insights into the physiology of raised intracranial pressure in IIH. There are now an increasing number of ongoing clinical trials evaluating weight loss methods and novel targeted therapies, such as 11ß-HSD1 inhibition and Glucagon-like peptide 1 (GLP-1) receptor agonists.

SUMMARY

Several studies are evaluating new therapies for IIH. Monitoring techniques are advancing, aiding diagnosis and allowing the clinician to accurately evaluate changes in papilloedema and intracranial pressure.

Association Between Peripapillary Bruch's Membrane Shape and Intracranial Pressure: Effect of Image Acquisition Pattern and Image Analysis Method, a Preliminary Study

Background/Aims: High intracranial pressure (ICP) is associated with changes in peripapillary Bruch's membrane (pBM) shape on optical coherence tomography (OCT) images of the optic nerve head. It is not known if image acquisition pattern and analysis method impact this association.

Materials and Methods: Cross sectional OCT scans of the optic nerve head were obtained at six angles using a radial scan pattern in 21 subjects immediately prior to ICP measurement via lumbar puncture. On each image, Bruch's membrane was manually segmented and defined by either 14 or 16 semi-landmarks and either rater identified, or distance identified boundaries. For each of these four image analysis strategies, geometric morphometric analysis identified the first principal component of Bruch's membrane shape for all images and for the set of images taken at each angle. Repeated measures ANOVA of the first principal component magnitude (PC1) for all images assessed for shape difference between image angles. Linear generalized estimating equation models assessed association between angle specific first principal component magnitudes (PC1) and ICP for each angle. Receiver operating characteristic analysis assessed angle specific PC1s' ability to differentiate elevated from normal ICP.

Results: The first principal component represented deflection into the vitreous for all scan angles, but quantitatively differed across scan angles (p < 0.005, repeated measures ANOVA). Angle specific first principal components were positively correlated with ICP (p < 0.005 for all angles, generalized estimating equation models). All angle specific first principal components showed excellent ability to classify ICP (area under curve ≥ 0.8 for all). These results were independent from image analysis strategy.

Discussion: Though qualitative changes in Bruch's membrane shape are similar regardless of cross-sectional angle of the 2-D OCT scan, they differ quantitatively between OCT scan angles, meaning that pBM is not axially symmetric and therefore PC1 extracted from different 2-D scan angles can't be compared between individuals. However, we do not identify an optimal scan angle for classification of ICP since there is a similarly strong linear relationship between the first principal component of shape and ICP and angle specific first principal components of Bruch's membrane shape showed similarly excellent ability to differentiate elevated from normal ICP. The results support development of Bruch's membrane shape extracted from 2-D cross sectional optic nerve head OCT scans as a biomarker of ICP and emphasize the importance of consistency of scan angle. This is relevant for developing diagnostic protocols that use OCT to detect high ICP states.

Complications in Patients Undergoing Microsurgical Clipping of Intracranial Aneurysms with Pre-existing Ventriculoperitoneal Shunts Following a Cranial Procedure

INTRODUCTION

Patients with ventriculoperitoneal/pleural (VP) shunts occasionally must undergo subsequent craniotomy, craniectomy, or cranioplasty. Due to changes in pressure dynamics following shunt placement, we hypothesized that such patients may have an increased risk of developing symptomatic collections of extra-axial blood, fluid, and/or air postoperatively, leading to longer stays and worse outcomes compared to those undergoing cranial operations without a VP shunt.

METHODS

From a retrospective cohort of patients who underwent cranial operations for management of cerebral aneurysms in 2005-2014, we identified patients who previously had a VP shunt placed, determined the temporal relationship between shunt placement and cranial operation, and investigated outcomes in those with and without a shunt.

RESULTS

Of 818 patients who underwent cranial operations, 28 (3.4%) had a VP shunt. Four of these 28 (14.3%, 95% confidence interval [CI] 4.0%-32.7%) developed postoperative complications, compared to 42 of 790 (5.3%, 95% CI 4.0%-7.1%) without a history of VP shunt (P = .07). In addition, patients with a shunt were more likely to have longer cranial procedures (P = .04), longer hospital stays (P = .05), and more computed tomography scans during their craniotomy-associated admission (P = .002). Multivariate analysis, though not significant, demonstrated that the presence of a shunt contributed to the development of complications (odds ratio [OR] 2.24, 95% CI .70-7.13, P = .17). Length of surgery (OR 1.17, 95% CI 1.04-1.31, P = .01) and length of stay (OR 1.04, 95% CI 1.01-1.07, P = .01) were significantly longer in those with a postoperative complication.

CONCLUSION

We found a nonsignificant trend toward increased postoperative complications in patients with a VP shunt who underwent a subsequent cranial operation.

Comparison of cross sectional optical coherence tomography images of elevated optic nerve heads across acquisition devices and scan protocols

Background

Optic nerve head measurements extracted from optical coherence tomography (OCT) show promise for monitoring clinical conditions with elevated optic nerve heads. The aim of this study is to compare reliability within and between raters and between image acquisition devices of optic nerve measurements derived from OCT scans in eyes with varying degrees of optic nerve elevation.

Methods

Wide angle line scans and narrow angle radial scans through optic nerve heads were obtained using three spectral domain(SD) OCT devices on 5 subjects (6 swollen optic nerves, 4 normal optic nerves). Three raters independently semi-manually segmented the internal limiting membrane(ILM) and Bruch’s membrane(BM) on each scan using customized software. One rater segmented each scan twice. Segmentations were qualitatively and quantitatively compared. Inter-rater, intra-rater and inter-device reliability was assessed for the optic nerve cross sectional area calculated from the ILM and BM segmentations using intraclass correlation coefficients and graphical comparison.

Results

Line scans from all devices were qualitatively similar. Radial scans for which frame rate could not be adjusted were of lower quality. Intra-rater reliability for segmentation and optic nerve cross sectional area was better than inter-rater reliability, which was better than inter-device reliability, though all ICC exceeded 0.95. Reliability was not impacted by the degree of optic nerve elevation.

Conclusions

SD-OCT devices acquired similar quality scans of the optic nerve head, with choice of scan protocol affecting the quality. For image derived markers, variability between devices was greater than that attributable to inter and intra-rater differences.

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).

Gaze-Evoked Deformations in Optic Nerve Head Drusen: Repetitive Shearing as a Potential Factor in the Visual and Vascular Complications

PURPOSE

To determine if ocular ductions deform intrapapillary and peripapillary tissues in optic nerve head drusen (ONHD) and to compare these deformations with healthy eyes and eyes with other optic neuropathies.

DESIGN

Observational case series.

PARTICIPANTS

Twenty patients with ONHD.

METHODS

Axial rasters of the optic nerve from a spectral-domain OCT device (Cirrus 5000; Carl Zeiss Meditec, Inc, Dublin, CA) were used to analyze the shape of the peripapillary basement membrane (ppBM) layer in 20 confirmed cases of ONHD. We compared registered images obtained from 2 eye positions: 10° to 15° in adduction and 30° to 40° in abduction. Geometric morphometrics was used to analyze the shape of the ppBM layer defined by placing 10 equidistant landmarks extending 2500 μm on both sides of the basement membrane opening. We also adapted an image strain tracking technique to measure regional intrapapillary strains in 6 patients. Using manually placed nodes on the reference image (in adduction), an iterative, block-matching algorithm is used to determine local displacements between the reference and its paired image in abduction. Displacement vectors were used to calculate the mean shear and effective strain (percent change).

MAIN OUTCOME MEASURES

Peripapillary shape deformations, intrapapillary shear strains, and effective strains.

RESULTS

We found a statistically significant difference in the shape of the ppBM layer between abduction and adduction (P < 0.01). The deformation was characterized by a relative posterior displacement temporally in adduction that reversed in abduction. Strain tracking in all 6 patients showed substantial gaze-induced shearing and effective strains. Mean effective strains were 7.5% outside the drusen. Shear and effective strains were significantly larger outside versus within the drusen (P < 0.003 and P < 0.01, respectively).

CONCLUSIONS

This study demonstrates that horizontal ocular ductions induce significant shearing deformations of the peripapillary retina and prelaminar intrapapillary tissues. We also found that the deformations in healthy persons are similar in magnitude to ONHD. Based on these findings, we speculate that patients with intrapapillary calcifications exposed to the long-term effects of repetitive shearing (induced by ocular ductions) may contribute to the progressive axonal loss and vascular complications associated with ONHD.

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.

Peripapillary Retinal Pigment Epithelium Layer Shape Changes From Acetazolamide Treatment in the Idiopathic Intracranial Hypertension Treatment Trial

Purpose

Recent studies indicate that the amount of deformation of the peripapillary retinal pigment epithelium and Bruch's membrane (pRPE/BM) toward or away from the vitreous may reflect acute changes in cerebrospinal fluid pressure. The study purpose is to determine if changes in optic-nerve-head (ONH) shape reflect a treatment effect (acetazolamide/placebo + weight management) using the optical coherence tomography (OCT) substudy of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) at baseline, 3, and 6 months.

Methods

The pRPE/BM shape deformation was quantified and compared with ONH volume, peripapillary retinal nerve fiber layer (pRNFL), and total retinal (pTR) thicknesses in the acetazolamide group (39 subjects) and placebo group (31 subjects) at baseline, 3, and 6 months.

Results

Mean changes of the pRPE/BM shape measure were significant and in the positive direction (away from the vitreous) for the acetazolamide group (P < 0.01), but not for the placebo group. The three OCT measures reflecting the reduction of optic disc swelling were significant in both treatment groups but greater in the acetazolamide group (P < 0.01).

Conclusions

Change in the pRPE/BM shape away from the vitreous reflects the effect of acetazolamide + weight management in reducing the pressure differential between the intraocular and retrobulbar arachnoid space. Weight management alone was also associated with a decrease in optic nerve volume/edema but without a significant change in the pRPE/BM shape, implying an alternative mechanism for improvement in papilledema and axoplasmic flow, independent of a reduction in the pressure differential. (ClinicalTrials.gov number, NCT01003639.)

Quantitative Association Between Peripapillary Bruch's Membrane Shape and Intracranial Pressure

Purpose

The purpose of this study was to determine if there is a quantitative relationship between chronic intracranial pressure (ICP) and peripapillary Bruch's membrane (pp-BM) shape and to determine whether change in pp-BM shape can be detected within 1 hour after ICP lowering by lumbar puncture (LP).

Methods

In this study, 30° nasal-temporal optical coherence tomography B-scans were obtained within 1 hour before and after LP in 39 eyes from 20 patients (age = 23–86 years, 75% female, ICP [opening pressure] = 10–55 cm H₂O). A total of 16 semi-landmarks defined pp-BM on each image. Geometric morphometric analysis identified principal components of shape in the image set. Generalized estimating equation models, accounting for within-subject correlation, were used to identify principal components that were associated with chronic ICP (comparing pre-LP images between eyes) and/or acute ICP changes (comparing pre- and post-LP images within eyes). The pp-BM width and anterior pp-BM location were calculated directly from each image and were studied in the same manner.

Results

Principal component 1 scalar variable on pre-LP images was associated with ICP (P < 0.0005). Principal component 4 magnitude changed within eyes after LP (P = 0.003). For both principal components 1 and 4, lower ICP corresponded with a more posterior position of pp-BM. Chronic ICP was associated with both pp-BM width (6.81 μm/cm H₂O; P = 0.002) and more anterior location of temporal and nasal pp-BM margins (3.41, 3.49 μm/cm H₂O; P < 0.0005, 0.002).

Conclusions

This study demonstrates a quantitative association between pp-BM shape and chronic ICP level. Changes in pp-BM shape are detectable within 1 hour of lowering ICP. pp-BM shape may be a useful marker for chronic ICP level and acute ICP changes. Further study is needed to determine how pp-BM shape changes relate to clinical markers of papilledema.

Update on Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is a disorder of elevated intracranial pressure of unknown cause occurring predominantly in young women of childbearing age. The typical patient symptom profile is the presence of daily headache, pulse synchronous tinnitus, transient visual obscurations, and papilledema with its associated visual loss. Although surgical procedures are performed for those who fail medical therapy, their relative efficacy remains unclear. The main morbidity of IIH is from visual loss. This visual loss is present in most patients and can usually be reversed if recognized early in the patients' course and treated.

Optical Coherence Tomography in Neuro-ophthalmology

The afferent visual pathway is a functionally eloquent region of the central nervous system (CNS). Key clinical features of inflammatory, ischemic, and compressive CNS lesions can be appreciated through detailed ophthalmic examination. Optical coherence tomography (OCT) provides a noninvasive means of capturing manifestations of axonal and neuronal loss in the CNS. OCT represents a surrogate marker of structural integrity in the CNS, through which mechanisms of neurodegeneration and repair may be better understood. In this article, the role of OCT in facilitating the diagnosis and management of several CNS disorders is discussed.

The Effect of Treatment of Idiopathic Intracranial Hypertension on Prevalence of Retinal and Choroidal Folds

PURPOSE

We described 3 types of folds in the retina and a crease in the outer retina associated with papilledema owing to idiopathic intracranial hypertension (IIH) at presentation. We report the change in folds relative to treatment of IIH over the 6 months.

METHODS

In this substudy of a randomized clinical trial, study eyes of subjects assigned to acetazolamide (ACZ, n = 44) or placebo (PLB, n = 43) had spectral-domain optical coherence tomography (SDOCT) images of the optic disc and macula regions at baseline and at 3 and 6 months. Images were evaluated for peripapillary wrinkles (PPW), retinal folds (RF), choroidal folds (CF), and creases using transaxial and en face views. The optic nerve head (ONH) shape, retinal nerve fiber layer (RNFL) thickness, ONH volume, and papilledema grade were measured. Outcome was determination of the presence or absence of PPW, RF, CF, and creases.

RESULTS

At presentation, except for an increase of PPW in ACZ eyes (64% vs 28%), both treatment groups were matched for all OCT features. At 6 months, ACZ-treated, but not PLB-treated, eyes had fewer folds of all types (P < .01), with a 57% reduction in frequency of RF. Creases did not resolve. Resolution of RF, but not of PPW and CF, was associated with significant reduction in RNFL thickness, ONH volume, and papilledema grade.

CONCLUSIONS

The various types of retinal folds associated with papilledema reflect biodynamic processes and show an ACZ treatment effect. Persistence of these folds despite marked improvement in ONH swelling suggests permanent changes in the affected retinal tissues.

Deformation of Optic Nerve Head and Peripapillary Tissues by Horizontal Duction

PURPOSE

To ascertain deformation of the optic nerve head (ONH) and peripapillary tissues caused by horizontal duction.

DESIGN

Prospective, experimental study.

METHODS

Optical coherence tomography of the ONH region was performed in 23 eyes of 12 normal volunteers in central gaze and increasing (10, 20, and 30 degrees) adduction and abduction. Main outcome measures were changes from central gaze in the configuration of the ONH and peripapillary tissues in eccentric gazes.

RESULTS

Adduction but not abduction was associated with significant, progressive relative posterior displacement of the temporal peripapillary retinal pigment epithelium (tRPE) from its position in central gaze reaching 49 ± 10 μm in 30-degree adduction (standard error of mean, P < .0001). Absolute (anterior or posterior) optic cup displacement (OCD) averaged 41 ± 7 μm in 30-degree adduction. Linear regression showed significant effect of adduction on absolute OCD (slope 1.09 ± 0.36 μm/degree, P = .0037). In 20-degree and 30-degree adduction, all eyes exhibited significant progressive temporal ONH tilting reaching 3.1 ± 0.4 degrees in 30-degree adduction (P < .0001). Abduction was not associated with significant peripapillary RPE displacement, OCD, or ONH tilt. Both nasal and temporal peripapillary choroid averaged 9-19 μm thinner in adduction and abduction than in central gaze (P < .02).

CONCLUSIONS

Adduction temporally tilts and displaces the prelaminar ONH and peripapillary tissues. Both adduction and abduction compress the peripapillary choroid. These effects support magnetic resonance imaging and biomechanical evidence that adduction imposes strain on the ONH and peripapillary tissues. Repetitive strain from eye movements over decades might in susceptible individuals lead to optic neuropathies such as normal tension glaucoma.

Translating the Low Translaminar Cribrosa Pressure Gradient Hypothesis into the Clinical Care of Glaucoma

Glaucoma is an optic neuropathy with multiple known risk factors, including age, race, family history, and intraocular pressure. Unfortunately, the only currently modifiable risk factor in treating the disease is intraocular pressure (IOP). Recent studies have investigated intracranial pressure (ICP) and the translaminar cribrosa pressure gradient as a potential explanation for glaucomatous optic nerve vulnerability across a range of IOP values. The difference between these two pressures across the lamina cribrosa may have an effect on the optic nerve, which could provide another modifiable parameter in the battle against glaucoma. In order for modification of the translaminar pressure gradient to be considered in the treatment of glaucoma, noninvasive methods to accurately measure ICP need to be developed. The translaminar pressure gradient could be therapeutically adjusted by either further lowering the IOP or raising the ICP when it is pathologically low, if possible.

Optical Coherence Tomography for the Radiologist

Optical coherence tomography is an imaging technique using low coherence light sources to produce high-resolution cross-sectional images. This article reviews pertinent anatomy and various pathologies causing optic atrophy (eg, compressive, infiltrating, demyelinating) versus optic nerve swelling (from increased intracranial pressure known as papilledema or other optic nerve intrinsic pathologies). On optical coherence tomography, optic atrophy is often associated with reduced average retinal nerve fiber layer thickness, whereas optic nerve swelling is usually associated with increased average retinal nerve fiber layer thickness.

Optical imaging of the optic nerve: beyond demonstration of retinal nerve fiber layer loss

Although we are still early in the evolution of optical imaging of the optic nerve, the available techniques already play an important role in clinical decision making. I would summarize our findings to date as follows: For acute ON: Presentation: OCT shows RNFL swelling, normal GCL + IPL by OCT; 1 month: OCT and SLP show RNFL thinning and swelling, GCL + IPL thinning by OCT; 3 months or later: OCT and SLP show RNFL thinning, further mild GCL thinning by OCT; 6 months: RNFL and GCL + IPL thinning finished. For acute NAION: Presentation: OCT shows RNFL swelling and SLP shows loss of birefringence, normal GCL + IPL by OCT; 1 month: RNFL swelling and thinning by OCT and thinning by SLP, GCL + IPL thinning by OCT; 3 months or later: RNFL and further mild GCL + IPL thinning; 6 months: RNFL and GCL + IPL thinning finished. For IIH Papilledema with mild vision loss: Presentation: OCT shows swelling of RNFL, TRT, and ONH volume; Presentation: OCT shows normal GCL + IPL; Presentation: OCT shows neural canal border inward deflection; 6 months: OCT shows structural shape changes reflecting the effectiveness of treatment.

Understanding idiopathic intracranial hypertension: mechanisms, management, and future directions

Idiopathic intracranial hypertension is a disorder characterised by raised intracranial pressure that predominantly affects young, obese women. Pathogenesis has not been fully elucidated, but several causal factors have been proposed. Symptoms can include headaches, visual loss, pulsatile tinnitus, and back and neck pain, but the clinical presentation is highly variable. Although few studies have been done to support evidence-based management, several recent advances have the potential to enhance understanding of the causes of the disease and to guide treatment decisions. Investigators of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) reported beneficial effects of acetazolamide in patients with mild visual loss. Studies have also established weight loss as an effective disease-modifying treatment, and further clinical trials to investigate new treatments are underway. The incidence of idiopathic intracranial hypertension is expected to increase as rates of obesity increase; efforts to reduce diagnostic delays and identify new, effective approaches to treatment will be key to meeting the needs of a growing number of patients.

Retinal and Choroidal Folds in Papilledema

PURPOSE

To determine the frequency, patterns, associations, and biomechanical implications of retinal and choroidal folds in papilledema due to idiopathic intracranial hypertension (IIH).

METHODS

Retinal and choroidal folds were studied in patients enrolled in the IIH Treatment Trial using fundus photography (n = 165 study eyes) and spectral-domain optical coherence tomography (SD-OCT; n = 125). We examined the association between folds and peripapillary shape, retinal nerve fiber layer (RNFL) thickness, disc volume, Frisén grade, acuity, perimetric mean deviation, intraocular pressure, intracranial pressure, and refractive error.

RESULTS

We identified three types of folds in IIH patients with papilledema: peripapillary wrinkles (PPW), retinal folds (RF), and choroidal folds (CF). Frequency, with photos, was 26%, 19%, and 1%, respectively; SD-OCT frequency was 46%, 47%, and 10%. At least one type of fold was present in 41% of patients with photos and 73% with SD-OCT. Spectral-domain OCT was more sensitive. Structural parameters related to the severity of papilledema were associated with PPW and RF, whereas anterior deformation of the peripapillary RPE/basement membrane layer was associated with CF and RF. Folds were not associated with vision loss at baseline.

CONCLUSIONS

Folds in papilledema are biomechanical signs of stress/strain on the optic nerve head and load-bearing structures induced by intracranial hypertension. Folds are best imaged with SD-OCT. The patterns of retinal and choroidal folds are the products of a complex interplay between the degree of papilledema and anterior deformation of the load-bearing structures (sclera and possibly the lamina cribrosa), both modulated by structural geometry and material properties of the optic nerve head. (ClinicalTrials.gov number, NCT01003639.).