Disk Structures Research Articles

The structures of protoplanetary disks

Astronomical observations of gas, dust, and rocky material in the disks from which planets emerge help refine theoretical ideas about how they form.

What happened before?

Context. Planets form in circumstellar disks around pre-main-sequence stars. A key question is, how do the formation and evolution of protoplanetary disks depend on stellar mass? Studies of circumstellar disks at infrared and submillimeter wavelengths around intermediate-mass Herbig Ae/Be stars have revealed disk structures such as cavities, gaps, and spiral arms. The Herbig Ae/Be stars represent an older population of intermediate-mass pre-main-sequence stars. Since these evolve toward the main sequence on timescales comparable to those of typical disk dissipation, a full picture of disk dispersal in intermediate-mass pre-main-sequence stars must include the intermediate-mass T Tauri (IMTT) stars. Aims. We seek to find the precursors of the Herbig Ae/Be stars in the solar vicinity within 500 pc from the Sun. We do this by creating an optically selected sample of IMTT stars from the literature, here defined as stars of masses 1.5 M⊙≤ M*≤ 5 M⊙ and with a spectral type between F and K3. Methods. We used literature optical photometry (0.4–1.25 μm) and distances determined from Gaia DR2 parallax measurements together with Kurucz stellar model spectra to place the stars in a HR diagram. We employed Siess evolutionary tracks to identify IMTT stars from the literature and derived masses and ages. We used Spitzer spectra to classify the disks around the stars into Meeus Group I and Group II disks based on their [F30/F13.5] spectral index. We also examined the 10 μm silicate dust grain emission and identified emission from polycyclic aromatic hydrocarbons (PAH). From this, we built a qualitative picture of the disks around the IMTT stars and compared this with available spatially resolved images at infrared and submillimeter wavelengths to confirm our classification. Results. We find 49 IMTT stars with infrared excess. The identified disks are similar to the older Herbig Ae/Be stars in disk geometries and silicate dust grain population. The detection frequency of PAHs is higher than from disks around lower mass T Tauri stars but less frequent than from Herbig Ae/Be disks. Spatially resolved images at infrared and submillimeter wavelengths suggest gaps, and spirals are also present around the younger precursors to the Herbig Ae/Be stars. Conclusions. Comparing the timescale of stellar evolution toward the main sequence and current models of protoplanetary disk evolution, the similarity between Herbig Ae/Be stars and the IMTT stars points toward an evolution of Group I and Group II disks that are disconnected and represent two different evolutionary paths.

An unusual case of infective spondylodiscitis caused by Campylobacter fetus subsp. fetus: molecular characterization by whole-genome sequencing

Spondylodiscitis is an infectious inflammation that affects the intervertebral disc and adjacent structures. Treating infective spondylodiscitis is often challenging due to the lack of specific symptoms. Here we present an unusual case of infective spondylodiscitis caused by Campylobacter fetus subsp. fetus.

A Stellar Mass Dependence of Structured Disks: A Possible Link with Exoplanet Demographics

Abstract Gaps in protoplanetary disks have long been hailed as signposts of planet formation. However, a direct link between exoplanets and disks remains hard to identify. We present a large sample study of ALMA disk surveys of nearby star-forming regions to disentangle this connection. All disks are classified as either structured (transition, ring, extended) or nonstructured (compact) disks. Although low-resolution observations may not identify large-scale substructure, we assume that an extended disk must contain substructure from a dust evolution argument. A comparison across ages reveals that structured disks retain high dust masses up to at least 10 Myr, whereas the dust mass of compact, nonstructured disks decreases over time. This can be understood if the dust mass evolves primarily by radial drift, unless drift is prevented by pressure bumps. We identify a stellar mass dependence of the fraction of structured disks. We propose a scenario linking this dependence with that of giant exoplanet occurrence rates. We show that there are enough exoplanets to account for the observed disk structures if transitional disks are created by exoplanets more massive than Jupiter and ring disks by exoplanets more massive than Neptune, under the assumption that most of those planets eventually migrate inwards. On the other hand, the known anticorrelation between transiting super-Earths and stellar mass implies those planets must form in the disks without observed structure, consistent with formation through pebble accretion in drift-dominated disks. These findings support an evolutionary scenario where the early formation of giant planets determines the disk’s dust evolution and its observational appearance.

The growth of super-Earths

The conditions in the protoplanetary disk are determinant for the various planet formation mechanisms. We present a framework that combines self-consistent disk structures with the calculations of the growth rates of planetary embryos via pebble accretion, in order to study the formation of super-Earths. We first perform 2D hydrodynamical simulations of the inner disks, considering a grain size distribution with multiple chemical species and their corresponding size and composition dependent opacities. The resulting aspect ratios are almost constant with orbital distance, resulting in radially constant pebble isolation masses, the mass where pebble accretion stops. This supports the “peas-in-a-pod” constraint from the Kepler observations. The derived pebble sizes are used to calculate the growth rates of planetary embryos via pebble accretion. Disks with low levels of turbulence (expressed through the α-viscosity) and/or high dust fragmentation velocities allow larger particles, hence lead to lower pebble isolation masses, and the contrary. At the same time, small pebble sizes lead to low accretion rates. We find that there is a trade-off between the pebble isolation mass and the growth timescale; the best set of parameters is an α-viscosity of 10−3 and a dust fragmentation velocity of 10 m s−1, mainly for an initial gas surface density (at 1 AU) greater than 1000 g cm−2. A self-consistent treatment between the disk structures and the pebble sizes is thus of crucial importance for planet formation simulations.

Spiral structures in gravito-turbulent gaseous disks

Context.Gravitational instabilities can drive small-scale turbulence and large-scale spiral arms in massive gaseous disks under conditions of slow radiative cooling. These motions affect the observed disk morphology, its mass accretion rate and variability, and could control the process of planet formation via dust grain concentration, processing, and collisional fragmentation.Aims.We study gravito-turbulence and its associated spiral structure in thin gaseous disks subject to a prescribed cooling law. We characterize the morphology, coherence, and propagation of the spirals and examine when the flow deviates from viscous disk models.Methods.We used the finite-volume code PLUTOto integrate the equations of self-gravitating hydrodynamics in three-dimensional spherical geometry. The gas was cooled over longer-than-orbital timescales to trigger the gravitational instability and sustain turbulence. We ran models for various disk masses and cooling rates.Results.In all cases considered, the turbulent gravitational stress transports angular momentum outward at a rate compatible with viscous disk theory. The dissipation of orbital energy happens via shocks in spiral density wakes, heating the disk back to a marginally stable thermal equilibrium. These wakes drive vertical motions and contribute to mix material from the disk with its corona. They are formed and destroyed intermittently, and they nearly corotate with the gas at every radius. As a consequence, large-scale spiral arms exhibit no long-term global coherence, and energy thermalization is an essentially local process.Conclusions.In the absence of radial substructures or tidal forcing, and provided a local cooling law, gravito-turbulence reduces to a local phenomenon in thin gaseous disks.

Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface.

We study self-assembly on a spherical surface of a model for a binary mixture of amphiphilic dimers in the presence of guest particles via Monte Carlo (MC) computer simulation. All particles had a hard core, but one monomer of the dimer also interacted with the guest particle by means of a short-range attractive potential. We observed the formation of aggregates of various shapes as a function of the composition of the mixture and of the size of guest particles. Our MC simulations are a further step towards a microscopic understanding of experiments on colloidal aggregation over curved surfaces, such as oil droplets.

Phenotypic recapitulation and correction of desmoglein-2-deficient cardiomyopathy using human-induced pluripotent stem cell-derived cardiomyocytes.

Desmoglein-2, encoded by DSG2, is one of the desmosome proteins that maintain the structural integrity of tissues, including heart. Genetic mutations in DSG2 cause arrhythmogenic cardiomyopathy, mainly in an autosomal dominant manner. Here, we identified a homozygous stop-gain mutations in DSG2 (c.C355T, p.R119X) that led to complete desmoglein-2 deficiency in a patient with severe biventricular heart failure. Histological analysis revealed abnormal deposition of desmosome proteins, disrupted intercalated disk structures in the myocardium. Induced pluripotent stem cells (iPSCs) were generated from the patient (R119X-iPSC), and the mutated DSG2 gene locus was heterozygously corrected to a normal allele via homology-directed repair (HDR-iPSC). Both isogenic iPSCs were differentiated into cardiomyocytes [induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs)]. Multielectrode array analysis detected abnormal excitation in R119X-iPSC-CMs but not in HDR-iPSC-CMs. Micro-force testing of three-dimensional self-organized tissue rings (SOTRs) revealed tissue fragility and a weak maximum force in SOTRs from R119X-iPSC-CMs. Notably, these phenotypes were significantly recovered in HDR-iPSC-CMs. Myocardial fiber structures in R119X-iPSC-CMs were severely aberrant, and electron microscopic analysis confirmed that desmosomes were disrupted in these cells. Unexpectedly, the absence of desmoglein-2 in R119X-iPSC-CMs led to decreased expression of desmocollin-2 but no other desmosome proteins. Adeno-associated virus-mediated replacement of DSG2 significantly recovered the contraction force in SOTRs generated from R119X-iPSC-CMs. Our findings confirm the presence of a desmoglein-2-deficient cardiomyopathy among clinically diagnosed dilated cardiomyopathies. Recapitulation and correction of the disease phenotype using iPSC-CMs provide evidence to support the development of precision medicine and the proof of concept for gene replacement therapy for this cardiomyopathy.

Gas Evolution in Inner Disk Cavities from a Synergic Analysis of IR-CO and UV-H2 Spectra

Abstract We are conducting a multi-wavelength analysis of high-resolution molecular spectra that probe the evolution of gas in the inner 10 au in protoplanetary disks. A sample of 15 disks has been combined to probe a range of inner disk structures including small and large dust cavities. Half of the sample has been observed in far-ultraviolet H2 emission with a new HST-COS program (GO-14703), that we have combined to near-infrared spectra of CO emission as observed with VLT-CRIRES and IRTF-iSHELL. This synergic dataset traces the evolution and depletion of CO and H2 in inner disk cavities and shows an evolving radial stratification of the molecular gas, where CO lines are narrower than H2 lines in disks with cavities. CO rotation diagrams also show significant evolution, suggesting a change in gas excitation as CO emission recedes to larger disk radii.

Collision rates of planetesimals near mean-motion resonances

ABSTRACT In circumstellar discs, collisional grinding of planetesimals produces second-generation dust. While it remains unclear whether this ever becomes a major component of the total dust content, the presence of such dust, and potentially the substructure within it, can be used to explore a disc’s physical conditions. A perturbing planet produces non-axisymmetric structures and gaps in the dust, regardless of its origin. The dynamics of planetesimals, however, will be very different than that of small dust grains due to weaker gas interactions. Therefore, planetesimal collisions could create dusty disc structures that would not exist otherwise. In this work, we use N-body simulations to investigate the collision rate profile of planetesimals near mean-motion resonances. We find that a distinct bump or dip feature is produced in the collision profile, the presence of which depends on the libration width of the resonance and the separation between the peri- and apocentre distances of the edges of the resonance. The presence of one of these two features depends on the mass and eccentricity of the planet. Assuming that the radial dust emission traces the planetesimal collision profile, the presence of a bump or dip feature in the dust emission at the 2:1 mean-motion resonance can constrain the orbital properties of the perturbing planet. This assumption is valid, so long as radial drift does not play a significant role during the collisional cascade process. Under this assumption, these features in the dust emission should be marginally observable in nearby protoplanetary discs with ALMA.

Anisotropy-independent packing of confined hard ellipses

We have examined the close-packed structure and ordering properties of hard ellipses between two parallel hard walls by using geometrical conjectures and Monte Carlo simulations. Starting from closely packed hard disk structures, we discover two competing densest packings of ellipses with the stretching of hard disks into different directions. We find that parallel and tilted close-packed structures alternate with widening pore width up to the two-dimensional bulk limit, where both structures produce the same close packing value (η=π/12). Our results highlight that the densest packing does not depend on the aspect ratio of the ellipse. This universal behavior is confirmed for three different aspect ratios (κ=2, 3, and 4) using replica exchange Monte Carlo simulation. Our simulation results show that even the global phase diagram is universal, where layering transitions between parallel structures and tilted-parallel structural changes are present.

A Review of Possible Advective Disk Structures around a Black Hole with Two Types of Gas Inflows

Abstract We studied general advective accretion solutions around a Kerr black hole (BH) by investigating two types of inflow gases at the outer accretion boundary (AB). We classified these two types of gases as cold-mode and hot-mode inflow gas at the outer AB on the basis of their temperatures and solutions. We found that the hot-mode gas is more efficient for angular momentum transport around the outer AB than the cold-mode gas. The hot-mode gas can give multiple global (popular as a shock solution) or single sonic point solutions, and the cold-mode gas can give a smooth global solution (popularly known as advection-dominated accretion flow) or two sonic point solutions. These solutions are also presented on a plane in energy and angular momentum (B ob−L 0) parameter space. For the first time, we explored theoretically the relation between the nature of accretion solutions and the nature of the initial accreting gas at the AB with a detailed computational and possible physical analysis. We also found that the surface density of the flow is highly affected by changes in the temperature at the AB, which can alter the radiative emissivities of the flow. The flow variables of various advective solutions are also compared. On the basis of those results, we plotted some inner disk structures around the BHs. By doing so, we conjecture on the persistent/transient nature of spectral states, soft excess, and timescales of variabilities around the BH X-ray binaries and active galactic nuclei.

Exploring HNC and HCN line emission as probes of the protoplanetary disk temperature

Context. The distributions and abundances of molecules in protoplanetary disks are powerful tracers of the physical and chemical disk structures. The abundance ratios of HCN and its isomer HNC are known to be sensitive to gas temperature. Their line ratios might therefore offer a unique opportunity to probe the properties of the emitting gas. Aims. We investigate the HNC and HCN line emission in disks at (sub-)millimeter wavelengths and explore their potential utility for probing disk temperature and other disk properties. Methods. Using the 2D thermochemical code DALI, we ran a set of disk models accounting for different stellar properties and radial and vertical disk structures, with an updated chemical network for the nitrogen chemistry. These modeling results were then compared with observations, including new observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of HNC J = 3−2 for the TW Hya disk and HNC J = 1−0 for 29 disks in Lupus. Results. Similar to CN, HCN and HNC have brighter line emission in models with larger disk flaring angles and higher UV fluxes. HNC and HCN are predicted to be abundant in the warm surface layer and outer midplane region, which results in ring-shaped emission patterns. However, the precise emitting regions and emission morphology depend on the probed transition, as well as on other parameters such as C and O abundances. The modeled HNC-to-HCN line intensity ratio increases from <0.1 in the inner disk to up to 0.8 in the outer disk regions, which can be explained by efficient HNC destruction at high temperatures. Disk-integrated HNC line fluxes from current scarce observations and its radial distribution in the TW Hya disk are broadly consistent with our model predictions. Conclusions. The HNC-to-HCN flux ratio robustly increases with radius (decreasing temperature), but its use as a chemical thermometer in disks is affected by other factors, including UV flux and C and O abundances. High-spatial resolution ALMA disk observations of HNC and HCN that can locate the emitting layers would have the great potential to constrain both the disk thermal and UV radiation structures, and also to verify our understanding of the nitrogen chemistry.

Study of the Feasibility of Conventional MR Images and Magnetic Resonance (MR)/Ultra-Short Echo Time (UTE) Technique in the Evaluation of Lumbar Disc Degeneration in the Axial Plane

The advantage and value of magnetic resonance (MR)-ultra-short echo time (UTE) technique in the displaying the structures of degenerative intervertebral discs were observed through evaluating the lumbar disc degeneration in the axial plane by conventional MR image and MR-UTE technique. A total of 160 examinees screened by inclusion and exclusion criteria were enrolled, and a total of 800 intervertebral disks were involved, and the degree of intervertebral disc degeneration was classified by conventional MR image classification method. After the first echo image of MR-UTE technique was integrated with the contour, the image entered UTE cartilage endplate, fibrous ring and osseous endplate. The integrity of the intervertebral disc from the above and below the intervertebral disc and the correlation of the structural endplate with the integrities of cartilage endplate, fibrous ring and osseous endplate under double echo sequence were analyzed, and the correlation analysis of the two categorical variables was conducted using rank correlation analysis. Under the MR-UTE sequence, there was no statistical significant difference in structural integrity constituent ratio (intact structure only on one side, incomplete structure on both side) between the non-low back pain group and the low back pain group (P > 0.05), the proportion of complete structure disappearance was lowest, and the proportion of partial structure disappearance was highest; there was a significant difference in the structural integrity of fibrous ring between the non-low back pain group and the low back pain group (P < 0.05), there was a statistical significant difference in structural integrity of fibrous rings between the two groups (P < 0.05); there was a statistical significant difference in pain degree between the partial structure disappearance group and the complete structure disappearance group (P < 0.05). There was no significant difference in pain degree between the groups (intact structure only on one side and incomplete structure on both side); conventional MR images showed no significant difference in the intervertebral disc degeneration degree between the non-low back pain group and low back pain group (P > 0.05), and the intervertebral disc degeneration degree had no significant correlation with the lower back pain. MR-UTE sequence and T2WI sequence showed that there was a correlation between different intervertebral disc degeneration degrees and the structural integrity distributions of cartilage endplate, osseous endplate and fibrous rings in two groups of patients with or without low back pain (P < 0.05). Whether low back pain exists or not has little effect on the intervertebral disc degeneration degree on T2WI. MR-UTE double echo sequence scan reveals that the intervertebral disc degeneration degree is positively related to the integrity and integrity distribution of cartilage endplate, fibrous ring and bone endplate.

Spin-Wave Emission from Vortex Cores under Static Magnetic Bias Fields.

We studied the influence of a static in-plane magnetic field on the alternating-field-driven emission of nanoscale spin waves from magnetic vortex cores. Time-resolved scanning transmission X-ray microscopy was used to image spin waves in disk structures of synthetic ferrimagnets and single ferromagnetic layers. For both systems, it was found that an increasing magnetic bias field continuously displaces the wave-emitting vortex core from the center of the disk toward its edge without noticeably altering the spin-wave dispersion relation. In the case of the single-layer disk, an anisotropic lateral expansion of the core occurs at higher magnetic fields, which leads to a directional rather than radial-isotropic emission and propagation of waves. Micromagnetic simulations confirm these findings and further show that focusing effects occur in such systems, depending on the shape of the core and controlled by the static magnetic bias field.

Tracing molecular stratification within an edge-on protoplanetary disk

High-resolution observations of edge-on protoplanetary disks in emission from molecular species that sample different critical densities and formation pathways offer the opportunity to trace the vertical chemical and physical structures of protoplanetary disks. Among the problems that can be addressed is the origin and significance of the bright CN emission that is a ubiquitous feature of disks. Based on analysis of subarcsecond-resolution Atacama Large Millimeter Array archival data for the edge-on Flying Saucer disk (2MASS J16281370-2431391), we establish the vertical and radial differentiation of the CN emitting regions of the disk with respect to those of 12CO and CS, and we model the physical disk conditions from which the CN emission arises. We demonstrate that the 12CO (2–1), CN (2–1), and CS J = 5–4 emitting regions of the disk decrease in scale height above the midplane, such that 12CO, CN, and CS trace layers of increasing density and decreasing temperature. We find that at radii >100 au from the central star, CN emission predominantly arises from intermediate layers, while in the inner region of the disk CN appears to arise from layers closer to the midplane. We investigate the physical conditions of the disk within the CN emitting regions, as well as the ranges of CN excitation temperature and column density, via RADEX non-local thermodynamic equilibrium (non-LTE) modeling of the three brightest CN hyperfine lines. Near the disk midplane, where we derive densities of nH2 ~ 107 cm−3 at relatively low Tkin (~12 K), we find that CN is thermalized, while sub-thermal, non-LTE conditions appear to obtain CN emission from higher (intermediate) disk layers. We consider whether and how the particular spatial location and excitation conditions of CN emission from the Flying Saucer can be related to CN production that is governed, radially and vertically, by the degree of irradiation of the flared disk by X-rays and UV photons from the central star.

Binary Planetesimal Formation from Gravitationally Collapsing Pebble Clouds

Abstract Planetesimals are compact astrophysical objects roughly 1–1000 km in size, massive enough to be held together by gravity. They can grow by accreting material to become full-size planets. Planetesimals themselves are thought to form by complex physical processes from small grains in protoplanetary disks. The streaming instability (SI) model states that millimeter/centimeter-sized particles (pebbles) are aerodynamically collected into self-gravitating clouds that then directly collapse into planetesimals. Here we analyze ATHENA simulations of the SI to characterize the initial properties (e.g., rotation) of pebble clouds. Their gravitational collapse is followed with the PKDGRAV N-body code, which has been modified to realistically account for pebble collisions. We find that pebble clouds rapidly collapse into short-lived disk structures from which planetesimals form. The planetesimal properties depend on the cloud’s scaled angular momentum, l = L / ( MR H 2 Ω ) , where L and M are the angular momentum and mass, R H is the Hill radius, and Ω is the orbital frequency. Low-l pebble clouds produce tight (or contact) binaries and single planetesimals. Compact high-l clouds give birth to binary planetesimals with attributes that closely resemble the equally sized binaries found in the Kuiper Belt. Significantly, the SI-triggered gravitational collapse can explain the angular momentum distribution of known equally sized binaries—a result pending verification from studies with improved resolution. About 10% of collapse simulations produce hierarchical systems with two or more large moons. These systems should be found in the Kuiper Belt when observations reach the threshold sensitivity.

Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late Infall Causing Disk Misalignment and Dynamic Structures in SU Aur*

Abstract Gas-rich circumstellar disks are the cradles of planet formation. As such, their evolution will strongly influence the resulting planet population. In the ESO DESTINYS large program, we study these disks within the first 10 Myr of their development with near-infrared scattered-light imaging. Here we present VLT/SPHERE polarimetric observations of the nearby class II system SU Aur in which we resolve the disk down to scales of ∼7 au. In addition to the new SPHERE observations, we utilize VLT/NACO, HST/STIS, and ALMA archival data. The new SPHERE data show the disk around SU Aur and extended dust structures in unprecedented detail. We resolve several dust tails connected to the Keplerian disk. By comparison with ALMA data, we show that these dust tails represent material falling onto the disk. The disk itself shows an intricate spiral structure and a shadow lane, cast by an inner, misaligned disk component. Our observations suggest that SU Aur is undergoing late infall of material, which can explain the observed disk structures. SU Aur is the clearest observational example of this mechanism at work and demonstrates that late accretion events can still occur in the class II phase, thereby significantly affecting the evolution of circumstellar disks. Constraining the frequency of such events with additional observations will help determine whether this process is responsible for the spin–orbit misalignment in evolved exoplanet systems.

Dynamical evolution of massive perturbers in realistic multicomponent galaxy models I: implementation and validation

ABSTRACT Galaxies are self-gravitating structures composed by several components encompassing spherical, axial, and triaxial symmetry. Although real systems feature heterogeneous components whose properties are intimately connected, semi-analytical approaches often exploit the linearity of the Poisson’s equation to represent the potential and mass distribution of a multicomponent galaxy as the sum of the individual components. In this work, we expand the semi-analytical framework developed in Bonetti et al. (2020) by including both a detailed implementation of the gravitational potential of exponential disc (modelled with a sech2 and an exponential vertical profile) and an accurate prescription for the dynamical friction experienced by massive perturbers (MP) in composite galaxy models featuring rotating disc structures. Such improvements allow us to evolve arbitrary orbits either within or outside the galactic disc plane. We validate the results obtained by our numerical model against public semi-analytical codes as well as full N-body simulations, finding that our model is in excellent agreement to the codes it is compared with. The ability to reproduce the relevant physical processes responsible for the evolution of MP orbits and its computational efficiency make our framework perfectly suited for large parameter-space exploration studies.

A novel biomarker for increased intracranial pressure in idiopathic intracranial hypertension.

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). Retrospective study METHODS: We included 54 eyes of 28 patients with bilateral papilledema who had peripapillary SD-OCT imaging within 24h 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. Bruch Membrane openingand 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 1785µm, with a sensitivity of 78.8% and a specificity of 81%. The cut off value for maximal RNFL thickness was 174µm, with a sensitivity of 75.8% and a specificity of 61.9%. 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.