Radial Scanning Research Articles

Detection of melanocytes in skin histopathological images using radial line scanning

In the diagnosis of skin melanoma by analyzing histopathological images, the detection of the melanocytes in the epidermis area is an important step. However, the detection of the melanocytes from the epidermis area is difficult because other keratinocytes that are very similar to the melanocytes are also present. This paper proposes a novel computer-aided technique for detection of the melanocytes in the epidermis area of skin histopathological images. An adaptive threshold technique is first applied to segment all the keratinocytes in the image. In order to distinguish the melanocytes from other keratinocytes, a novel technique based on radial line scanning is proposed to estimate the halo region of the melanocytes. Based on the estimated halo region of all the nuclei, an area ratio of estimated halo region and the nuclei is used to detect the melanocytes from all the keratinocytes. Experimental results on 40 different histopathological images of skin tissue containing 341 melanocytes show that the proposed technique provides a superior performance.

Longitudinal In Vivo Imaging of Retinal Ganglion Cells and Retinal Thickness Changes Following Optic Nerve Injury in Mice

BackgroundRetinal ganglion cells (RGCs) die in sight-threatening eye diseases. Imaging RGCs in humans is not currently possible and proof of principle in experimental models is fundamental for future development. Our objective was to quantify RGC density and retinal thickness following optic nerve transection in transgenic mice expressing cyan fluorescent protein (CFP) under control of the Thy1 promoter, expressed by RGCs and other neurons.Methodology/Principal FindingsA modified confocal scanning laser ophthalmoscopy (CSLO)/spectral-domain optical coherence tomography (SD-OCT) camera was used to image and quantify CFP+ cells in mice from the B6.Cg-Tg(Thy1-CFP)23Jrs/J line. SD-OCT circle (1 B-scan), raster (37 B-scans) and radial (24 B-scans) scans of the retina were also obtained. CSLO was performed at baseline (n = 11) and 3 (n = 11), 5 (n = 4), 7 (n = 10), 10 (n = 6), 14 (n = 7) and 21 (n = 5) days post-transection, while SD-OCT was performed at baseline and 7, 14 and 35 days (n = 9) post-transection. Longitudinal change in CFP+ cell density and retinal thickness were computed. Compared to baseline, the mean (SD) percentage CFP+ cells remaining at 3, 5, 7, 10, 14 and 21 days post-transection was 86 (9)%, 63 (11)%, 45 (11)%, 31 (9)%, 20 (9)% and 8 (4)%, respectively. Compared to baseline, the mean (SD) retinal thickness at 7 days post-transection was 97 (3)%, 98 (2)% and 97 (4)% for the circle, raster and radial scans, respectively. The corresponding figures at 14 and 35 days post-transection were 96 (3)%, 97 (2)% and 95 (3)%; and 93 (3)%, 94 (3)% and 92 (3)%.Conclusions/SignificanceLongitudinal imaging showed an exponential decline in CFP+ cell density and a small (≤8%) reduction in SD-OCT measured retinal thickness post-transection. SD-OCT is a promising tool for detecting structural changes in experimental optic neuropathy. These results represent an important step towards translation for clinical use.

Parametric study on bending and thickening in laser forming of a bowl shaped surface

Shaping a circular sheet into a bowl requires in-plane thickening as well as out-of-plane bending. Combinations of radial and circular laser scan paths can make that. In this work, the effects of various process parameters, viz. laser spot diameter, laser power and scan speed, on the in-plane and out-of-plane forming of stainless steel circular blanks were studied for various circular and radial scan schemes. Taguchi method was used to plan the experimental runs. Both bending angle and thickness increment for circular and radial scan schemes, respectively, were found to increase with reducing laser beam diameter and scan speed, and increasing laser power. The experimental results were corroborated with the predictions by simplified analytical models. Further, the bending angle was found to increase with increasing radius of the circular scan path. Increase in the number or in the length of radial scan lines increased the thickness increment and the bending angle, induced due to the resultant shrinkage in the periphery of the blanks. It was found that the combination of radial and circular scan schemes works better for achieving higher bending angle with smaller coefficient of variation, which gives a measure of wrinkling in the formed blanks.

Normal corneal thickness measurements in pigmented rabbits using spectral‐domain anterior segment optical coherence tomography

To document the thickness of the central cornea in pigmented rabbits using spectral-domain anterior segment optical coherence tomography (AS-OCT). Seventeen pigmented rabbits (6 male, 11 female, both eyes) were involved in this study. Thirty-four eyes from healthy pigmented rabbits underwent a complete ophthalmologic examination, including AS-OCT. Eight radial scans, 6 mm in length and centered on the cornea, were obtained using the AS-OCT. Corneal thickness was automatically calculated using pachymetry software. Measurements were displayed as the mean and standard deviation for each of the 17 regions defined by the software. The regions were the center (1 mm radius, area a), the inner ring (2.5 mm radius, area b), the outer ring (3 mm radius, area c), and the eight radial scan lines in eight directions (Superior (1), SN (2), Nasal (3), IN (4), Inferior (5), IT (6), Temporal (7), ST (8)) with an angle of 45° between each consecutive scan line (a, b 1-8, c 1-8). There was no statistically significance difference in corneal thickness between gender, eye, and the eight directions (P = 0.804, P > 0.05, P > 0.05). There was a statistical difference between the thickness in areas a, b, and c (P < 0.05). The corneal thickness increased gradually from the center to the periphery of the 6 mm measured. The center corneal thickness was 387 ± 19.8 μm for OD and 384 ± 20.2 μm for OS. The corneal thicknesses of the thinnest point of the right eyes (OD) and the left eyes (OS) were 376 ± 20.2 and 370 ± 16.8 μm, respectively. There was positive correlation between the thinnest point and area a in both the right eyes (r = 0.892, P < 0.001) and the left eyes (r = 0.832, P < 0.001). This is the first documentation of the rabbit corneal thickness in vivo using the spectral-domain AS-OCT. Pigmented rabbit corneas were almost 150 μm thinner than human corneal values. Gender and eye were not associated with any statistical differences in central corneal thickness in this study.

Regions of kinetic geodesic acoustic modes and streamers in JIPPT-IIU tokamak plasmas

The radial extent of kinetic geodesic acoustic modes (KGAMs) and streamers is measured using a heavy ion beam probe. Intense KGAM oscillations are observed in the core region of a low-density ohmic (OH) plasma where Te ≫ Ti and outside this region, streamers characterized by steepening fronts are observed. The radial profile of plasma density stays flat in the region of the streamers, showing a rise in the plasma density in two regions, one at the scrape-off layer and the other in the core region during the radial scan of sample volumes. Intense (up to eΦ/kTe ∼ 0.1) and broad GAM oscillations (δf/f ∼ 0.5) are observed in the r < ap/2 region of tokamak plasmas. GAM oscillations and streamers are strongly reduced in the heated phase. In addition, the radial profile of the spectra of GAM in the heated phase is very different from that of a low-density OH plasma. The streamers and the two-step rise in the density radial profile disappear in the heated phase.

Flow-gated radial phase-contrast imaging in the presence of weak flow

To implement a flow-gating method to acquire phase-contrast (PC) images of carotid arteries without use of an electrocardiography (ECG) signal to synchronize the acquisition of imaging data with pulsatile arterial flow. The flow-gating method was realized through radial scanning and sophisticated post-processing methods including downsampling, complex difference, and correlation analysis to improve the evaluation of flow-gating times in radial phase-contrast scans. Quantitatively comparable results (R=0.92-0.96, n=9) of flow-related parameters, including mean velocity, mean flow rate, and flow volume, with conventional ECG-gated imaging demonstrated that the proposed method is highly feasible. The radial flow-gating PC imaging method is applicable in carotid arteries. The proposed flow-gating method can potentially avoid the setting up of ECG-related equipment for brain imaging. This technique has potential use in patients with arrhythmia or weak ECG signals.

Antifungal and antibacterial functions of medicinal leech recombinant destabilase-lysozyme and its heated-up derivative

Antifungal activity of recombinant medicinal leech destabilase-lysozyme (rec.Dest-Lys) was investigated by using fungi: Botrytis cinerea, and Verticillium lateriticum, including yeasts Candida guillermoudii and Shizosaccharomyces pombe. Its antibacterial activity was investigated on gram-negative bacteria Pseudomonas fluorescens. These activities were assessed by radial agar diffusion assay, and scanning and transmission electron microscopy. Therefore, destabilase-lysozyme not only is endo-isopeptidase and lysozyme, but also has antifungal and antibacterial activities. Muramidase activity of rec. Dest-Lys disappeared after heat-treating at 90°C for 50 min without the loss of its antimicrobial activity. Furthermore we showed for the first time that the heated-up derivative of rec.Dest-Lys exhibited more potent activities against the above enumerated fungi and gram-negative bacteria than original protein.

OVERCOMING SEGMENTATION ERRORS IN MEASUREMENTS OF MACULAR THICKNESS MADE BY SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY

To assess the frequency and severity of segmentation errors in spectral-domain optical coherence tomography, and present an appropriate scan protocol for measuring macular thickness. In this study we examined 40 eyes of healthy subjects, 45 eyes with retinal pathology and 31 eyes with subretinal pathology. Patients were prospectively imaged using 12 radial scans and 3-dimensional macular cube scans by spectral-domain optical coherence tomography (3D OCT-1000; Topcon Corp., Japan) at the same sitting. Retinal segmentation errors were noted and graded using a subjective, categoric error scale to generate an error score. We compared the macular thickness measurements with and without error correction, and between the two scan protocols. In this series, 63.8% of eyes (74 of 116 eyes) gave at least 1 segmentation error. Errors were more common in eyes with pathology. There was a significant difference between measurements of macular thickness with and without correcting these errors, regardless of scan protocol (P < 0.05). After error correction of both scan protocols, the macular thickness measurements obtained with the 12 radial scan protocol were equivalent to those obtained with the 3-dimensional macular cube scan protocol. Segmentation errors were frequent on scans obtained by spectral-domain optical coherence tomography. We recommend the 12 radial scan protocol with error correction as the standard protocol for measuring macular thickness, particularly in clinical studies.

The structure and ferroelectric property of La-doped BiFeO3/SrTiO3 artificial superlattice structure by rf sputtering: Effect of deposition temperature

Improvement of ferroelectric property by Lanthanum (La)-doping of BiFeO3 (BFO) and strain effect of high quality superlattice films deposited at temperature ≧700°C was shown in this study. The in-pane (200) radial scans showed that films at deposition temperature above 700°C behaved high strained ~−1.4% and showed epitaxity properties. The La-doped BFO superlattice structure also behaved higher polarization value ~197μC/cm2 and lower leakage current density comparing with BFO superlattice structure shown in our previous study. The ferroelectric properties of superlattice structures are enhanced by lattice strain and strongly correlated with the defect state of films.

Choroidal Thickness and Volume Mapping by a Six Radial Scan Protocol on Spectral-Domain Optical Coherence Tomography

To report a 6 radial scan protocol, which simply generates a topographic map of choroidal thickness and volume on a commercial spectral-domain optical coherence tomography (SD-OCT) device. We analyzed the features of the resulting choroidal maps in healthy eyes. Prospective, noncomparative case series. Eighty eyes from 40 healthy volunteers who visited the healthcare clinic of Hanyang University Hospital from December 2010 to February 2011. All participants underwent a 6 radial scanning protocol using an SD-OCT device. In a single session, the device produces 6 high-resolution averaging B-scan images. For segmentation of the choroid layer, the reference lines of the retinal boundary (internal limiting membrane-retinal pigment epithelium) were adjusted to the choroidal boundary (retinal pigment epithelium-choroid/sclera junction) in each of the 6 radial B-scans. A topographic map of choroidal thickness and volume was automatically generated by built-in software according to the Early Treatment Diabetic Retinopathy Study (ETDRS) layout. A statistical analysis was conducted to compare the choroidal thickness and volume measurements for each ETDRS subfield. An ETDRS-style topographic map of choroidal thickness and volume. The mean time required for segmentation adjustment was 167.4±15.8 seconds. The mean choroidal thickness of all ETDRS subfields was 285.9±53.0 μm, and the mean total choroidal volume of the entire ETDRS area was 7.72±1.2 mm(3). The nasal outer macula area was significantly smaller than any other ETDRS subfield (P<0.05) except for the adjacent superior and inferior outer macula subfields. Refractive error was correlated with choroidal thickness in all ETDRS subfields. Age was also correlated with choroidal thickness for almost all of the ETDRS subfields except for the temporal inner, nasal outer, and temporal outer macula areas. The total choroidal volume was correlated with the refractive error and age. A 6 radial scan protocol, using a commercial SD-OCT device, enables the production of reliable choroidal thickness and volume maps with an ETDRS layout. By using this protocol, more comprehensive choroidal evaluation is possible in clinical practice or research.

DIAGNOSTIC IMAGING SYSTEM AND PROCESSING METHOD FOR PRODUCING REDUCED FRAME RATE IMAGES FROM DATA COLLECTED AT A HIGHER FRAME RATES

An image diagnostic system controls a probe to perform radial scanning within a body cavity and to acquire reflected signals through the probe. The system produces data based on the signals, constructs and outputs tomographic images of the body cavity and biotissue surrounding the body cavity. The system includes an extraction unit for extracting portions of the produced data on the basis of a frame rate upon successively outputting the tomographic images, and a first output control unit for forming, based on the extracted data, real time tomographic images of the body cavity and biotissue which are outputted in real time during radial scanning. A storage device stores the produced data, and a second output control unit forms, subsequent to the radial scanning, tomographic images of the body cavity and biotissue based on the stored data which are then outputted.

Two Point Correlation Technique for the Measurements of Poloidal Plasma Rotation by Heavy Ion Beam Probe

The paper proposes a method to measure poloidal rotation velocity of toroidal plasma vpol using Heavy Ion Beam Probe (HIBP) with a multi-slit energy analyzer. The method is based on calculation of phase shift between broadband density turbulence measured simultaneously in two sample volumes, located at the same magnetic surface but separated poloidally. Oscillatory component of HIBP beam current is used as a density turbulence characteristic. HIBP is capable to provide the temporal evolution of the vpol in a fixed radial position and also the vpol profile by periodic radial scan. Method was verified in real plasma experiment in ECRH and NBI discharges on the TJ-II stellarator. Result shows that in low density discharges (ne ≈ 0.3-0.5 × 10 19 m −3 ) absolute values of local vpol is about 4-6 km/s, oriented in the ion diamagnetic drift direction. When HIBP operates for radial scans, it is conventionally measuring the plasma potential profile, and so provides the radial electric field Er and velocity of E × B drift (vE×B) at the same time as plasma rotation. Experimental data shows that in low density ECRH plasma the rotation velocity coincides with E × B velocity within achieved experimental accuracy. When the density is increasing, both vE×B and vpol tends to decrease and then change the sign at threshold plasma densities in the range of ne ≈ 0.7-1 × 10 19 m −3 . With this new proposed technique HIBP becomes the new effective tool to study plasma rotation and turbulence characteristics in toroidal plasmas.

Spectral domain OCT versus time domain OCT in the evaluation of macular features related to wet age-related macular degeneration

BackgroundThe aim of this study was to compare the agreement between spectral domain optical coherence tomography (SD OCT) and time domain stratus OCT (TD OCT) in evaluating macular morphology alterations in wet age-related macular degeneration (AMD).MethodsThis retrospective study was performed on 77 eyes of 77 patients with primary or recurring subfoveal choroidal neovascularization secondary to AMD. All patients underwent OCT examination using Zeiss Stratus OCT 3 (Carl Zeiss Meditec Inc, Dublin, CA) and Opko OTI Spectral SLO/OCT (Ophthalmic Technologies Inc, Toronto, Canada). In all radial line scans, the presence of intraretinal edema (IRE), serous pigment epithelium detachment (sPED), neurosensory serous retinal detachment (NSRD), epiretinal membrane (EM), inner limiting membrane thickening (ILMT), and hard exudates (HE) were evaluated. The degree of matching was quantified by Kappa measure of agreement.ResultsThe percentage distribution of TD OCT findings versus SD OCT findings was: IRE 36.3% versus 77.9%, sPED 57.1% versus 85.7%, NSRD 38.9% versus 53.2%, EM 10.5% versus 26.3%, ILMT 3.8% versus 32.4%, and HE 6.4% versus 54.5%. The agreement was as follows: sPED: kappa value 0.15; NSRD: kappa value 0.61; IRE: kappa value 0.18; EM: kappa value 0.41; ILMT: kappa value 0.02; HE: kappa value 0.06.ConclusionThe agreement in the evaluation of macular lesions between the two techniques is poor and depends on the lesion considered. SD OCT allows better detection of the alterations typically related to choroidal neovascularization such as IRE, PED, ILM thickening, and HE. Consequently its use should be strongly considered in patients with wet AMD.

Study of high frequency MHD modes from ECE radiometer in Tore Supra

Tore Supra ECE diagnostic has been recently upgraded to study MHD modes driven by energetic particles up to 400 kHz. To improve the measurement sensitivity, the ECE signals of the 32 channels radiometer were amplified just below the saturation limit and sources of noise were investigated in order to keep it as low as possible. With such an improvement, fast particle driven modes with frequencies up to 200 kHz were detected. A 4-channel correlation ECE system using YIG filters with tuneable frequency was also installed. It allows fine radial scans of MHD modes and correlation length measurements. For the two kinds of YIG filter in use, the minimum frequency separation between two ECE channels that could be achieved was established measuring the correlation coefficient between the respective radiation noises. Finally, by modelling the ECE radiometer taking into account the antenna radiation pattern and the vertical position of the ECE beam relative to the plasma centre we improved the data analysis tools, thus giving a better determination of the phase radial structure of ECE oscillations. The poloidal structure of MHD modes can then be identified from ECE data and, for off axis ECE lines of sight, the direction of the plasma rotation can also be determined. This method allows identifying the occurrence of an inverse cascade of electron fishbone modes ranging from m/n=4/4 to 1/1 (m and n are the poloidal and toroidal mode numbers, respectively) which appears in lower hybrid current drive plasmas.

Radial Scan法のフローアーチファクト抑制効果について

Radial scan method collects blades rotated about the k-space origin. The one blade is the group of the echo acquired each repetition time (TR) in concentric strips. Because each of the blades has the phase-encode direction, it can be expected to be dispersing flow artifact which appear in the phase-encode direction. We examined how to produce flow artifact in radial scan method without motion correction. Flow artifact does not appear like a mass in radial scan method. Background noise in radial scan method tended to decrease when width of the blade is thinner and a number of blades is larger under a number of echo is keeping. In conclusion, unlike past countermeasures against flow artifact in Cartesian method, flow artifact becomes inconspicuous to be dispersed by 360 degrees in radial scan method.

Recent results and prospects for correlation ECE measurements on TCV

The Tokamak a Configuration Variable (TCV) has a two channel correlation electron cyclotron emission (CECE) radiometer with a line of sight perpendicular to the magnetic field. The antenna pattern of this radiometer limits resolution to k < 112 m -1 or ks < 0.3 at 500 kHz. It can access the region with minor radius vol < 0.7. A series of measurements has been made of the turbulence spectra at positive and negative triangularity and as a function of collisionality. Also, a series of measurements has been made as a function of poloidal angle, by varying the plasma vertical position with respect to the antenna, the measurements being made on the same flux surface. It is planned to extensively upgrade the diagnostic by integrating four more channels and acquiring a new front-end for the radiometer. This upgrade should reduce the required number of shots for a radial scan by a factor four and improve the signal-to-noise ratio. It is also planned to use a high gain antenna that will extend access to kθ < 174m -1 or kθs < 0.5 at 500 kHz. The present system, measurements and the upgrade are described in this paper.

Prevalence of early and late stages of physiologic PVD in emmetropic elderly population

To investigate the early and late stages of posterior vitreous detachment (PVD) in the foveal area in correlation with age and gender. Three hundred and thirty-five emmetropic eyes of 271 Caucasian patients (216 women/119 men) were examined by optical coherence tomography (OCT) and ultrasound (US). Eyes were classified into groups according to the patients age (up to 69.9; 70-74.9; 75-79.9; over 80 years) and to the clinical findings [Vitreous state: Detached in US; Detached in OCT; Foveal adhesion (FA); Attached vitreous]. The mean age was 76 ± 8 ranging from 44 to 89 years in female and 72 ± 10 ranging from 46 to 87 years in male subjects. The vitreous was attached in 32% of all eyes, 18.5% had FA, 18.5% were detached in OCT and 68% were detached in US. While prevalence of FA decreases with increasing age, OCT-diagnosed detachments did not change significantly with age. Between the ages of 70 and 75, an increase in PVD rates occurred. The prevalence of PVD was similar in both genders. Women were significantly older than men in the late-stage PVD in the eyes. The use of OCT and US enabled us to detect a partial or total PVD in 80% of the eyes. A sudden increase in late-stage PVD between the ages of 70 and 75 was observed, correlating with the reported age prevalence of various macular diseases. In contrast to myopics, both genders of elderly emmetropics have a similar prevalence of PVD.

Corneal topographic analysis in patients with keratoconus using 3-dimensional anterior segment optical coherence tomography

To assess a new corneal topographer based on 3-dimensional anterior segment optical coherence tomography (OCT-based corneal topographer) for analyzing corneal topography in patients with keratoconus. Osaka University Graduate School of Medicine, Osaka, Japan. Evaluation of diagnostic test or technology. Keratoconic eyes and normal control eyes were assessed using a rotating Scheimpflug-based corneal topographer and an AS OCT-based corneal topographer. The OCT-based corneal topographer, a 1310 nm swept-source device, captures 8192 points during 0.34 second for 16 radial scans of the corneal topography. The success rate of precisely digitizing the corneal surfaces, patterns of the color-coded maps, central corneal thickness (CCT), and central axial power were compared between the 2 devices. Forty keratoconic eyes and 30 control eyes were assessed. The OCT-based corneal topographer measured corneal configurations despite corneal opacities. The success rate of precisely digitizing the corneal surfaces in keratoconic eyes was 95% using OCT and 80% using the Scheimpflug-based corneal topographer. The color-coded maps of the anterior and posterior corneal elevations, CCT, and corneal axial power maps generated by the 2 devices agreed well. The correlations between the CCT values and between the central corneal axial power values measured by the 2 devices were well correlated in both groups. The OCT-based corneal topographer, with its faster acquisition time, provided more consistent measurements than the Scheimpflug-based corneal topographer. The OCT-based corneal topographer seems promising for evaluating highly irregular corneas, as in cases of advanced keratoconus. No author has a financial or proprietary interest in any material or method mentioned.

Identification of Schlemm's Canal and Its Surrounding Tissues by Anterior Segment Fourier Domain Optical Coherence Tomography

To identify Schlemm's canal (SC) and trabecular meshwork (TM) by anterior segment Fourier-domain optical coherence tomography (AS-FD-OCT) with histologic confirmation in enucleated human eyes and to quantitatively evaluate SC and TM in living human eyes. In enucleated human eyes, the imaging of the anterior chamber angle by AS-FD-OCT was performed before and after surgical expansion of SC with an injection of a viscoelastic material, followed by histologic examination. In 60 living human eyes, the agreement of identification of SC between examiners was evaluated with the Cohen's κ values, and the lengths of SC and TM and the area of TM were measured on temporal and nasal sections of the AS-FD-OCT images. In enucleated human eyes, SC was observed to be a thin, linear, lucent space in the AS-FD-OCT image obtained with the high-definition raster scan protocol, but not in those obtained with the bi-angle radial scan protocol. This space was enlarged after the SC expansion. In the histologic study, the SC was confirmed to be in the same position as in the AS-FD-OCT images. The κ values of observable SC in living human subjects were 0.92 or higher. The axial length of the SC averaged 347.2 ± 42.3 μm, TM length 466.9 ± 60.7 μm, and TM area 0.0671 ± 0.0058 mm². These measurements showed sufficient repeatability and reproducibility. Using the high-definition images of the AS-FD-OCT, SC and its surrounding tissues were successfully observed in most of the living eyes and were quantitatively evaluated in a noninvasive manner.

Comparison of the Prevalence of Plateau Iris Configurations Between Angle-closure Glaucoma and Open-angle Glaucoma Using Ultrasound Biomicroscopy

To determine the prevalence of plateau iris configurations in acute primary angle-closure (APAC), chronic angle-closure glaucoma (CACG), and open-angle glaucoma (OAG) eyes using ultrasound biomicroscopy. The study included fellow eyes of 27 APAC patients, 26 OAG patients, and 26 CACG patients with no history of APAC. Patients with a history of earlier intraocular surgery or argon laser peripheral iridoplasty were excluded from the study. Eyes that had not undergone laser peripheral iridotomy were excluded from APAC and CACG groups. Radial scans were carried out using ultrasound biomicroscopy in all 4 quadrants. A plateau iris configuration within a quadrant was defined by the presence of an anteriorly positioned ciliary process, a narrow ciliary sulcus, a steeply rising peripheral iris, followed by a downward angulation from the corneoscleral wall and the presence of a flat iris plane. Eyes with plateau iris configurations were defined as those having at least 2 quadrants fulfilling these criteria. Plateau iris configurations were found in fellow eyes of 10 of 27 patients with (37.0%) APAC, 9 of 26 (34.6%) patients with CACG, and 5 of 26 (19.2%) patients with OAG. No significant difference in the prevalence of plateau iris configurations was observed among the 3 groups (P=0.314, χ2 test). Eyes with OAG had a higher rate of plateau iris configurations than expected. Longitudinal studies to evaluate plateau iris height are required to determine its significance in the pathogenesis of angle-closure glaucoma.