Layer Thickness Measurements Research Articles

Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry

In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on the fact that, except for the intrinsic uncertainties of the emission and straggling of alpha particles, their trajectories at different incident angles are distinct, with smaller ones corresponding to the incidence perpendicular to the detector surface. The result obtained (711 ± 23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the diode herein investigated is suitable for high resolution charged particle spectrometry.

Minimum Rim Width and Peripapillary Retinal Nerve Fiber Layer Thickness for Diagnosing Early to Moderate Glaucoma.

In a cross-sectional study from a Brazilian multiracial population, minimum rim width (MRW) and peripapillary retinal nerve fiber layer thickness measurements from OCT showed comparable diagnostic performance in discriminating early to moderate glaucoma from healthy eyes. The purpose of this study is to compare the ability of MRW and peripapillary retinal nerve fiber layer thickness (RNFLT) measurements in discriminating early to moderate glaucoma from healthy eyes in a Brazilian population. A total of 155 healthy controls and 118 patients with mild to moderate glaucoma (mean deviation >-12 dB) underwent MRW and RNFLT measurements with optical coherence tomography. Only 1 eye per patient was included in the analysis. A receiver operating characteristic (ROC) regression model was used to evaluate the diagnostic accuracy of MRW and RNFLT, whereas adjusting for age and Bruch membrane opening area. Sensitivities at fixed specificities of 95% were calculated for each parameter. Global RNFLT and MRW showed comparable area under the ROC curves [0.93 (0.91-0.96) and 0.93 (0.89-0.96), respectively; P =0.973]. Both parameters had similar sensitivities (75% vs. 74%, respectively; P =0.852) at a fixed specificity of 95%. The best sector for diagnosing glaucoma for both parameters was the temporal inferior sector, which showed an area under the ROC curve of 0.93 (0.87-0.96) for RNFLT and 0.91 (0.86-0.95) for MRW ( P =0.320). The temporal inferior sector showed similar sensitivities for RNFLT and MRW measurements (83% vs. 77%, respectively) at a fixed specificity of 95% (P =0.230). MRW and RNFLT measurements showed comparable diagnostic performance in discriminating early to moderate glaucoma from healthy eyes in a Brazilian multiracial population.

Retrograde Optic Nerve Degeneration in Pituitary Adenoma: A Study with RE-PERG.

RE-PERG is altered in presence of primary neuronal degeneration of retinal ganglion cells, both in glaucoma and other diseases. A previous study showed that in a model of retrograde degeneration (vascular dementia) RE-PERG was normal. In this study, we enrolled patients with pituitary adenoma (PA) to evaluate RE-PERG findings in another model of retrograde degeneration compared with healthy controls (HC). Based on the outcome of the present and our previous studies with RE-PERG, and reviewing the literature, we discuss the physiopathology of glaucoma. Twelve PA patients and 14 age-matched HC were recruited. All participants performed visual field (VF) test, retinal nerve fiber layer (RNFL) and ganglion cells complex (GCC) thickness measurement by means of optical coherence tomography (OCT), visual evoked potentials (VEPs) and RE-PERG, a non-invasive, fast steady-state pattern electroretinogram (SS-PERG) sampled in five consecutive blocks of 130 events. VEPs amplitude was significantly lower in PA with respect to HC (6.8±0.6 vs 7.4±0.6 µV; p=0.045). VEPs latency was higher in PA (123.2±5.8 vs 103.6±4.1 msec; p<0.01). As for VF, mean defect (MD) and pattern standard deviation (PSD) were higher in PA (-6.6±2.6 vs -0.01±1.02 dB; p<0.01 and 8.5±3.1 vs 1.5±0.3; p<0.01, respectively). RNFL thickness was lower in PA (88±8.1 vs 97±9.3 µ; p=0.01). There was no statistically significant difference between PA and HC for RE-PERG. There was a significant correlation among MD, PSD, VEPs amplitude, PERG amplitude and RNFL thickness in the PA group, whereas no correlation was found with SDPh, which remains as normal as in the HC group. Our findings confirm that RE-PERG is not altered in retrograde degeneration. Based on the outcome of the present and our previous studies about RE-PERG and glaucoma, we assume that in glaucoma a double mechanism of retinal ganglion cells degeneration, both retrograde and primary, can coexist.

Effectiveness of selective laser trabeculoplasty and its safety on corneal endothelium in patients with primary open angle glaucoma and ocular hypertension.

The aim of this study was to evaluate the effectiveness of selective laser trabeculoplasty (SLT) in patients with primary open-angle glaucoma (POAG) and ocular hypertension (OHT), and to assess its effects and safety on corneal endothelial cell morphology. Forty patients with POAG (15 cases, 23 eyes) and OHT (25 cases, 48 eyes) were prospectively evaluated. All cases underwent pachymetry, goniolens examination, Humphrey Visual Field Test, Optical Coherence Tomography, and Corneal Confocal Microscopy measurements. Patients whose intraocular pressure (IOP) was more than 21 mmHg in POAG and OHT, underwent SLT. SLT treatment was applied to the inferior 180° region of the trabecular meshwork. Central corneal thickness (CCT), IOP, and specular microscopy examinations were taken at the visits before and after the first day, first week, first month, third and sixth months of the SLT procedure. Retinal nerve fiber layer (RNFL) thickness measurements and visual field tests were performed before and six month post-SLT. Results of the pre-SLT and post-SLT measurements were compared and a P value of lower than 0.05 was considered statistically significant. The results of IOP measurements at first week, first month, third, and sixth month post-SLT were significantly lower than the results before and post-SLT first day. No significant difference was found between the results of initial and final measurements of CCT and specular microscopic corneal endothelial cell morphology evaluation. There was no statistically significant difference between the results of initial and final measurements for RNFL thickness and the results of the visual field tests. SLT is an effective treatment modality for reducing IOP in patients with POAG and OHT and is also a safe procedure in terms of the entirety of corneal endothelial cell morphology.

Optical coherence tomography changes in ankylosing spondylitis patients on long-term adalimumab treatment.

Long-term ocular effects of tumor necrosis factor-alpha inhibitors remain to be elucidated. This study aimed to examine the long-term effects of adalimumab use on neural tissue of the anterior visual pathways using optical coherence tomography in patients with ankylosing spondylitis. This was a single-center, open-label, cross-sectional study conducted at the Giresun University Faculty of Medicine, Physical Medicine and Rehabilitation Department, between November 2019 and August 2020. This study included 26 ankylosing spondylitis patients receiving adalimumab for at least 1 year and 21 healthy controls. All subjects underwent a full ophthalmological examination and optical coherence tomography examination with the following measurements: peripapillary retinal nerve fiber layer thickness, peripapillary retinal thickness, peripapillary choroidal thickness, ganglion cell complex thickness, and the optic head properties. Peripapillary retinal nerve fiber layer thickness and retinal thickness measurements were lower in the adalimumab group. In addition, ganglion cell complex thickness was significantly lower and the cup-to-disc ratio was significantly higher in the adalimumab group (p<0.05). However, the two groups did not differ in terms of peripapillary choroidal thickness and disc area (p>0.05). Although tumor necrosis factor-alpha inhibitors have some favorable effects on the ocular involvement of patients with ankylosing spondylitis, they may also have paradoxical detrimental effects as evidenced by structural changes observed by optical coherence tomography. Future studies with better design, probably including a large number of patients with a range of rheumatological diseases and tumor necrosis factor-alpha inhibitors, are warranted.

Deep Learning–Assisted Detection of Glaucoma Progression in Spectral-Domain OCT

To develop and validate a deep learning (DL) model for detection of glaucoma progression using spectral-domain (SD)-OCT measurements of retinal nerve fiber layer (RNFL) thickness. Retrospective cohort study. A total of 14034 SD-OCT scans from 816 eyes from 462 individuals. A DL convolutional neural network was trained to assess SD-OCT RNFL thickness measurements of 2 visits (a baseline and a follow-up visit) along with time between visits to predict the probability of glaucoma progression. The ground truth was defined by consensus from subjective grading by glaucoma specialists. Diagnostic performance was summarized by the area under the receiver operator characteristic curve (AUC), sensitivity, and specificity, and was compared with conventional trend-based analyses of change. Interval likelihood ratios were calculated to determine the impact of DL model results in changing the post-test probability of progression. The AUC, sensitivity, and specificity of the DL model. The DL model had an AUC of 0.938 (95% confidence interval [CI], 0.921-0.955), with sensitivity of 87.3% (95% CI, 83.6%-91.6%) and specificity of 86.4% (95% CI, 79.9%-89.6%). When matched for the same specificity, the DL model significantly outperformed trend-based analyses. Likelihood ratios for the DL model were associated with large changes in the probability of progression in the vast majority of SD-OCT tests. A DL model was able to assess the probability of glaucomatous structural progression from SD-OCT RNFL thickness measurements. The model agreed well with expert judgments and outperformed conventional trend-based analyses of change, while also providing indication of the likely locations of change. Proprietary or commercial disclosure may be found after the references.

Role of through-the-scope catheter–based EUS in inflammatory bowel disease diagnosis and activity assessment

Distinguishing Crohn's disease (CD) from ulcerative colitis (UC) may be difficult when the disease is limited to the colon. Transmural healing is an important adjunctive measure of inflammatory bowel disease activity. The aim of this study was to examine the role of EUS in differentiating CD versus UC and evaluating transmural disease activity. This prospective cohort study enrolled 20 patients with CD (10 active [aCD], 10 inactive), 20 patients with UC (10 active [aUC], 10 inactive), and 20 control subjects who underwent colonoscopy from 2019 to 2021 at a tertiary care center. Measurements of bowel wall layer thickness from the rectum and cecum were obtained using a through-the-scope US catheter (UM-3R-3; Olympus, Center Valley, Penn, USA) at the time of colonoscopy. Compared with control subjects, patients with aCD had thicker rectal submucosa and total wall layer (submucosa median, 1.80mm [interquartile range {IQR}, 1.40-2.00] vs .60mm [IQR, .40-.70]; total wall median, 3.70mm [IQR, 3.52-4.62] vs 2.10mm [IQR, 1.70-2.40], respectively; P< .01). Similar significant findings were observed for the cecal wall layers. Compared with control subjects, patients with aUC had thicker rectal mucosa and total wall but not submucosa or muscularis propria layers (mucosa median, 1.35mm [IQR, 1.12-1.47] vs .60mm [IQR, .57-.70]; total wall median, 3.45mm [IQR, 2.85-3.75] vs 2.10mm [IQR, 1.70-2.40], respectively; P< .01). Patients with aCD compared with those with aUC had a significantly thicker rectal submucosa layer (median, 1.80mm [IQR, 1.40-2.00] vs .55mm [IQR, .40-.75], respectively, P< .01). Cutoff values of 1.1mm for rectal submucosa in CD (sensitivity, 1.0; specificity, 1.0) and 1.1mm for rectal mucosa in UC (sensitivity, .8; specificity, .9) were found to differentiate active from inactive disease. EUS measurements of colon wall layers can help diagnose aCD versus aUC and assess transmural disease activity. (Clinical trial registration number: NCT03863886.).

Deep Learning Estimation of 10-2 Visual Field Map Based on Circumpapillary Retinal Nerve Fiber Layer Thickness Measurements

To estimate central 10-degree visual field (VF) map from spectral-domain optical coherence tomography (SD-OCT) retinal nerve fiber layer thickness (RNFL) measurements in glaucoma with artificial intelligence. Artificial intelligence (convolutional neural networks) study. This study included 5352 SD-OCT scans and 10-2 VF pairs from 1365 eyes of 724 healthy patients, patients with suspected glaucoma, and patients with glaucoma. Convolutional neural networks (CNNs) were developed to estimate the 68 individual sensitivity thresholds of 10-2 VF map using all-sectors (CNNA) and temporal-sectors (CNNT) RNFL thickness information of the SD-OCT circle scan (768 thickness points). 10-2 indices including pointwise total deviation (TD) values, mean deviation (MD), and pattern standard deviation (PSD) were generated using the CNN-estimated sensitivity thresholds at individual test locations. Linear regression (LR) models with the same input were used for comparison. The CNNA model achieved an average pointwise mean absolute error of 4.04 dB (95% confidence interval [CI] 3.76-4.35) and correlation coefficient (r) of 0.59 (95% CI 0.52-0.64) over 10-2 map and the mean absolute error and r of 2.88 dB (95% CI 2.63-3.15) and 0.74 (95% CI 0.67-0.80) for MD, and 2.31 dB (95% CI 2.03-2.61) and 0.59 (95% CI 0.51-0.65) for PSD estimations, respectively, significantly outperforming the LRA model. The proposed CNNA model improved the estimation of 10-2 VF map based on circumpapillary SD-OCT RNFL thickness measurements. These artificial intelligence methods using SD-OCT structural data show promise to individualize the frequency of central VF assessment in patients with glaucoma and would enable the reallocation of resources from patients at lowest risk to those at highest risk of central VF damage.

Can Lamina Cribrosa Indicate Optic Neuritis in Multiple Sclerosis?

In this study, we aimed to evaluate the association of lamina cribrosa thickness (LCT) and lamina cribrosa depth (LCD), as determined by spectral domain optical coherence tomography (SD-OCT), with visual evoked potentials (VEPs) in patients with multiple sclerosis (MS). Patients enrolled in this prospective, cross-sectional study were divided into three groups. Group 1 consisted of 25 relapsing-remitting MS patients with VEP pathology in one or both eyes. In patients with VEP pathology in both eyes, one eye was chosen randomly. Group 2 comprised 25 relapsing-remitting MS patients with no VEP pathology or optic neuritis history. A randomly selected single eye of each patient was evaluated. Group 3 consisted of 25 age- and sex-matched healthy volunteers; a randomly selected single eye of these participants was examined. LCT, LCD, and retinal nerve fiber layer (RNFL) thickness measurements were determined in four quadrants (superior, inferior, nasal, and temporal) by SD-OCT. The three groups were similar in terms of age and sex. The mean LCT was lower in Group 1 than in Group 2, but the difference was not statistically significant (268.80 ± 36.69 μm [min-max = 222-394 μm] versus 285.80 ± 12.00 μm [min-max = 249-338 μm]; P = 0.148). The mean LCT was significantly lower in Group 1 than in Group 3 (268.80 ± 36.69 μm [min-max = 222-394 μm] versus 294.80 ± 12.00 μm [min-max = 232-351 μm]; P = 0.012). There was a weak positive correlation between LCT and RNFL-inferior, RNFL-nasal, and RNFL-temporal. We found that the lamina cribrosa was thinner in MS patients with VEP pathology. To the best of our knowledge, this is a novel finding. Our results imply that LCT could be used as an indicator of optic neuritis in MS patients.

A mobile setup for simultaneous and in situ neutron reflectivity, infrared spectroscopy, and ellipsometry studies.

Neutron reflectivity at the solid/liquid interface offers unique opportunities for resolving the structure-function relationships of interfacial layers in soft matter science. It is a non-destructive technique for detailed analysis of layered structures on molecular length scales, providing thickness, density, roughness, and composition of individual layers or components of adsorbed films. However, there are also some well-known limitations of this method, such as the lack of chemical information, the difficulties in determining large layer thicknesses, and the limited time resolution. We have addressed these shortcomings by designing and implementing a portable sample environment for in situ characterization at neutron reflectometry beamlines, integrating infrared spectroscopy under attenuated total reflection for determination of molecular entities and their conformation, and spectroscopic ellipsometry for rapid and independent measurement of layer thicknesses and refractive indices. The utility of this combined setup is demonstrated by two projects investigating (a) pH-dependent swelling of polyelectrolyte layers and (b) the impact of nanoparticles on lipid membranes to identify potential mechanisms of nanotoxicity.

Choroidal thickness and retinal nerve fiber layer analysis in chronic spontaneous urticaria

Aim: In this study, we investigated the effects of chronic spontaneous urticaria on the choroid and retinal nerve fiber layer.&#x0D; Material and Method: The patient group consisted of newly diagnosed 54 chronic spontaneous urticaria (CSU ) patient and the control group consisted of 54 healthy volunteer. Choroidal and retinal nerve fiber layer (RNFL) thickness measurements were performed with Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) 30 minutes after pupil dilation with 0,5% tropicamide.&#x0D; Results: In the patient group, nasal choroidal thickness (NCT) was 290.11±43.16 μm, subfoveal choroidal thickness (SFCT) was 339.17±37.709 μm, temporal choroidal thickness (TCT) was 296.00±42.859 μm, mean choroidal thickness (MCT) was 308.33±35.923 μm and RNFL thickness was 91.11±7.393 μm. NCT was 248.42±35,742 μm, SFCT 276.56±40.04 μm, TCT 253.69±37.384 μm, MCT 259.50±32,986 μm and RNFL thickness 92.19±8.719 μm in the control group. When we examine the p value, it is seen that both groups are similar to each other in terms of RNFL thickness (p=0.326), while there is a significant thickening in all choroidal regions of patients with CSU, including NCT, SFCT, TCT, MCT (p=0.000, p=0.000, p=0.000, p=0.000, respectively). &#x0D; Conclusion: The choroid is affected in CSU and choroidal thickness can be a noninvasive method that can be used in diagnosis CSU. However, studies of longer disease durations may provide more illuminating information about CSU and choroid and RNFL.

Effect of shape on depth profile Nuclear Magnetic Resonance data of multilayered composite structure

ABSTRACT Polymer matrix composite structures with adhesively bonded rubber layers are being used for various industrial applications. The adhesive layer thickness (used for bonding composite and elastomer rubber layers) has to be uniform to achieve desired bond strength. However, this cannot be controlled in practical applications in industry as no physical measurements are possible for large structures. This paper reports application of single-sided portable Nuclear Magnetic Resonance (NMR) at a frequency of 12.88 MHz for the study of the adhesive layer thickness measurement as well as qualitative analysis of the adhesive layer used for bonding these materials. The effect of the shape of the sample on the proton NMR signal which is related indirectly to elastic properties was investigated. Results obtained on flat and curved glass fibre reinforced polymer (GFRP) composite samples were compared. Studies showed there is a change in single-sided NMR depth profile data (slope of amplitude versus depth curve) due to changes in the shape of the composite structure. A multilayer sample with rubber and propellant bonded adhesively to the composite structure was also tested to study the effect of shape on the profile NMR data.

Effect of Weiss ring on peripapillary retinal nerve fiber layer thickness measurements using SD-OCT

Spectral-domain optical coherence tomography (SD-OCT) must accurately identify and measure the peripapillary retinal nerve fiber layer (pRNFL) thickness to improve the repeatability and reproducibility, and reduce measurement errors. Because Weiss ring can be located in front of the optic disc, we hypothesized that it may affect pRNFL thickness measurements obtained using SD-OCT. We retrospectively reviewed the medical records of patients with (group W) and without (group N) Weiss ring, observed on OCT fundus image and an RNFL map devised using SD-OCT. Optic disc cube scans (200 × 200) were obtained to measure pRNFL thicknesses (superior, temporal, inferior, nasal, and average) at two consecutive visits. Pearson's correlation coefficient (r), intraclass correlation coefficient (ICC), and coefficient of variation (CV) were calculated. The r and ICC values for the pRNFL thickness measurements at the two visits were lower for group W compared to group N, but statistical significance was reached only for inferior pRNFL thickness. In addition, CV values were greater for group W compared to group N, but the differences were significant only for inferior and average pRNFL thickness measurements (p < 0.001 and p = 0.004, respectively). Weiss ring located near the optic disc can affect pRNFL thickness measurements and repeatability thereof, especially the inferior quadrant and average values. Therefore, it is important to identify the presence of Weiss ring when analyzing pRNFL thickness values.

Automatic asphalt layer interface detection and thickness determination from ground-penetrating radar data

Ground-penetrating radar (GPR) has been widely used in asphalt pavement layer thickness measurement. It requires the detection of pavement layer interfaces, which could be accomplished via manual inspection. This may be subjective and cause inaccurate thickness measurements due to the field data noise. Existing layer interface detection methods for thickness determination usually require customized programming and/or manual inputs for execution, which could hinder real-time applications. This article proposes an automatic method for asphalt pavement layer interface detection and thickness determination using GPR. The effects of in-situ noise levels on thickness measurement accuracy were discussed. The Canny edge detector was used to estimate the two-way travel time (TWTT) range. The wavelet transform was used for noise cancellation. Layer interface reflections were identified using the matched filter method for thickness determination. Vibration effect during the continuous GPR survey was mitigated using the empirical mode decomposition (EMD) method. A simulation study was conducted. The proposed method provided more accurate measurements than manual inspection for thickness values from 10.16 cm (4 in.) to 2.54 cm (1 in.). GPR field test was performed, and results were compared to field core thickness measurements. Results show that GPR-measured thickness errors are 6.5 % and 1.6 % using manual inspection and the proposed method, respectively. The proposed method is automatic and can be implemented using existing programming functions, which may enable real-time asphalt pavement thickness determination during GPR surveys.

Presentation and causes of optic disc oedema at a tertiary centre in Rajasthan

The purpose of this study was to assess the causes of optic disc oedema and their systemic associations and to study the various clinical presentations of optic disc oedema.This is a retrospective observational study which was conducted at Department of Ophthalmology, JLN Medical College, Ajmer. All patients who reported to OPD with Optic disc oedema during the study period (February2020 to August 2021) were evaluated. Complete ophthalmic examination included visual acuity, anterior segment examination using slit lamp, fundus examination using direct and indirect Ophthalmoscope and 90 Dioptre lens, B-scan for optic nerve sheath diameter (ONSD) and OCT for retinal nerve fibre layer thickness (RNFL) measurement. fundus photography was also done. Investigations like complete blood test, Visual field testing using perimetry, computed tomography scan and magnetic resonance imaging were done as and when indicated. Total 80 optic disc oedema cases were included in our study. Out of 80 cases, 44(55%) and 36(45%) were males and females respectively. Different causes of optic disc oedema were found to be papilloedema 48 cases (60%), optic neuritis 13 cases (16.25%), NA-AION 9 cases (11.25%), CRVO 3 cases (3.75%), diabetic papillopathy 2 cases (2.5%), traumatic optic neuropathy 2 cases (2.5%) respectively. In 3 cases (3.75%) cause could not be detected (idiopathic). The most common cause was papilloedema, followed by optic neuritis and NA- AION

Measurement of retinal nerve fiber layer thickness with a deep learning algorithm in ischemic optic neuropathy and optic neuritis

This work aims at determining the ability of a deep learning (DL) algorithm to measure retinal nerve fiber layer (RNFL) thickness from optical coherence tomography (OCT) scans in anterior ischemic optic neuropathy (NAION) and demyelinating optic neuritis (ON). The training/validation dataset included 750 RNFL OCT B-scans. Performance of our algorithm was evaluated on 194 OCT B-scans from 70 healthy eyes, 82 scans from 28 NAION eyes, and 84 scans of 29 ON eyes. Results were compared to manual segmentation as a ground-truth and to RNFL calculations from the built-in instrument software. The Dice coefficient for the test images was 0.87. The mean average RNFL thickness using our U-Net was not different from the manually segmented best estimate and OCT machine data in control and ON eyes. In NAION eyes, while the mean average RNFL thickness using our U-Net algorithm was not different from the manual segmented value, the OCT machine data were different from the manual segmented values. In NAION eyes, the MAE of the average RNFL thickness was 1.18 ± 0.69 μm and 6.65 ± 5.37 μm in the U-Net algorithm segmentation and the conventional OCT machine data, respectively (P = 0.0001).

Influences on Quantitative Nitriding Layer Thickness Measurements using Model-Based Photothermal Radiometry

Abstract In nitriding furnaces, the nitriding result is currently only controlled indirectly via the nitriding potential based on gas sensors. Detrimental properties such as soft spots, insufficient compound layer thickness or strongly porous zones, which might result from reduced surface reactivity, are thus only detected post-process. Therefore, in-process measurements of the layer formation promise a real benefit for energy efficiency and process quality enhancement. Photothermal radiometry is a promising contactless method for layer inspection that so far showed qualitative correlations of the photothermal phase signal with material parameters and layer thicknesses. In this article, thickness and thermal conductivity of the compound layer are quantitatively determined by using a physical signal model for a least-squares approximation of in-process measured photothermal phase signals. In addition, the influence of roughness and surface curvature is investigated, with the model-based photothermal layer thickness measurement showing robustness to different surface conditions and allowing quantification of the layer thickness with uncertainties &lt; 1 μm even during in-process measurement inside an industrial nitriding furnace.

Identifying and understanding optical coherence tomography artifacts that may be confused with glaucoma

Optical coherence tomography is often used for detection of glaucoma as well as to monitor progression. This paper reviews the most common types of artifacts on the optical coherence tomography report that may be confused with glaucomatous damage. We mainly focus on anatomy-related artifacts in which the retinal layer segmentation and thickness measurements are correct. In such cases, the probability maps (also known as deviation maps) show abnormal (red and yellow) regions, which may mislead the clinician to assume [...]

Intra- and interobserver assessments of intestinal wall thickness and segmentations from transverse sections of feline abdominal ultrasound images.

Measurements of intestinal wall thicknesses from ultrasound imaging (US) are routinely used to support diagnoses of intestinal disorders in cats, however published studies describing observer agreement are currently lacking. The aim of this retrospective, observer agreement study was to quantify inter- and intraobserver repeatability and agreement in the measurement of intestinal wall layer thicknesses and the segmentation of transverse sections of small intestines in US images of 20 cats. Intestinal wall layer thickness measurements of the mucosa, submucosa, muscularis, serosa layer, and total thickness of these layers were performed on five cats with small cell epitheliotropic lymphoma, five with inflammatory bowel disease, and 10 with other conditions. Thickness measurements and the segmentation encompassing the serosa layer were obtained from five observers four times non-sequentially. The average standard deviation in thickness measurements (95% confidence interval) in the mucosa, submucosa, muscularis, serosa, and total thickness were 0.35 (0.07-0.95), 0.24 (0.07-0.52), 0.22 (0.06-0.49), 0.20 (0.05-0.49), and 0.57 (0.11-1.60) mm, respectively. The average intraclass correlation coefficients, which estimates the degree of consistency in thickness measurements and segmentation areas for each observer, ranged from 0.355 to 0.870 and 0.850 to 0.993, respectively. The interclass correlation coefficient, which estimates the degree of consistency when measuring a thickness or segmentation area over all observers ranged from 0.115 to 0.753, and 0.811 to 0.902, respectively. The overall average Dice Coefficient, which estimates the extent of overlap of the segmentations for all observers was 0.957 (0.933 to 0.972). Our results suggest segmentations of small intestines have a higher interobserver agreement than measurements of intestinal wall thicknesses.

Çocuk Çölyak Hastalarında Laboratuvar Parametrelerinin Göz Yaşı Testleri ve Optik Koherens Tomografi Bulguları Üzerindeki Etkisi

Aim: The aim of this study was to evaluate the tear parameters and optical coherence tomography (OCT) findings in children with celiac disease (CD) and to investigate the relationship between these findings and laboratory data. Material and Methods: The study included 100 eyes of 50 CD patients as well as 110 eyes of 55 healthy subjects with no ocular pathology as a control group. Best corrected visual acuity was evaluated, baseline tear volume was estimated using standard Schirmer’s test, and fluorescein tear film break-up time (TBUT) was determined for all participants. Pupillary dilation was induced and macular sections and optic disc sections were obtained with OCT. Results: The patient and control groups showed no statistically significant differences in terms of age and gender distribution (p=0.490, and p=0.930, respectively). Mean Schirmer’s test measurement was significantly lower in the CD patients compared to the control group (14.07±5.14 mm vs. 20.20±3.93 mm, p&amp;lt;0.001). TBUT was also shorter in the CD patients compared to the control subjects (10.86±3.51 s vs. 15.25±2.49 s, p&amp;lt;0.001). Mean total retinal thickness and outer retinal thickness values were significantly lower in the patient group than in the control group (p&amp;lt;0.001, for both parameters). In addition, the mean retinal nerve fiber layer (RNFL) thickness measurement was significantly thinner in the patient group than in the control group (p&amp;lt;0.001). Conclusion: In the presented study, it was observed that macular and RNFL thickness were decreased in children with CD compared to the control group, and tear tests were also impaired.