جستجوی مقالات مرتبط با کلیدواژه « Retinal Nerve Fiber Layer » در نشریات گروه « پزشکی »

To evaluate diagnostic performance of ganglion cell inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) parameters measured with Cirrus high‑definition optical coherence tomography (OCT) in patients with preperimetric glaucoma.

In this multicenter cross-sectional study, 150 eyes of 83 patients with preperimetric glaucoma were compared with 200 eyes of age and sex matched healthy subjects. All patients had visual field testing and OCT scanning of GCIPL and RNFL in all quadrants. The independent Samples t‑test was used to determine if a difference exists between the means of two independent groups on a continuous dependent variable. The area under the receiver operating characteristic (ROC) curve (AUC) of each parameter was calculated for discriminatory ability between normal controls and preperimetric glaucoma. The sensitivity and specificity were estimated by point coordinates on ROC curve.

The best parameters for distinguishing preperimetric glaucoma from healthy eyes were the combined average GCIPL + average RNFL, followed by average RNFL + GCIPL (inferotemporal), and average RNFL + GCIPL (minimum). The GCIPL parameters with the highest to lowest AUC (in decreasing order) were inferotemporal, followed by average, minimum, superior, inferior, superonasal, inferonasal, superotemporal, and quadrants. The RNFL parameters with the highest to lowest AUC (in decreasing order) were average, followed by nasal, temporal, superior, and inferior quadrants. The sensitivity of combined GCIPL + RNFL parameters ranged 85%–88% and the specificity ranged 76%–88%. The sensitivity for RNFL parameters ranged 80%–90% and the specificity ranged 64%–88%.

GCIPL and RNFL have good discriminatory ability; the sensitivity and specificity increase when both parameters are combined for early detection of glaucoma.

 Based on literatures, the patients with essential tremor have a thinner Retinal Nerve Fiber Layer (RNFL) layer in Optical Coherence Tomography (OCT) imaging, compared to the healthy population. Thus, we decided to examine the ocular-neural state of patients with essential tremor, by examining RNFL and Retinal Ganglion Cell Layer (RGCL) in the OCT reports of patients referred to Hazrat Rasool Akram Hospital in the years 2020 to 2022.

 This research was implemented in the form of case-control study.50 patients were recruited into each group of tremor, and healthy controls. OCT parameters, including thickness of RNFL and RGCL were evaluated and recorded.

 The study findings revealed a significant difference in the mean superior, superior nasal, superior temporal sections of the right eye and superior temporal and inferior temporal regions of the left eye in RNFL between the control group and all patients (P < 0.01). Moreover, the results showed that there was a significant difference in the GCL in superior 6 mm of the right and left eye between the control group, and all patients (P <0.01).

 Regarding the results this study, it seems that patients with essential tremor have a significant decrease in some RNFL and GCL factors compared to healthy people. However, the majority of variables examined from RNFL and GCL in our study did not show significant differences. Moreover, this thinning could be associated with the neurodegenerative nature of the disease.

In this study, an algorithm based on deep learning was presented to reduce the retinal nerve fiber layer (RNFL) segmentation errors in spectral domain optical coherence tomography (SD-OCT) scans using ophthalmologists’ manual segmentation as a reference standard.

In this study, we developed an image segmentation network based on deep learning to automatically identify the RNFL thickness from B-scans obtained with SD-OCT. The scans were collected from Farabi Eye Hospital (500 B-scans were used for training, while 50 were used for testing). To remove the speckle noise from the images, preprocessing was applied before training, and postprocessing was performed to fill any discontinuities that might exist. Afterward, output masks were analyzed for their average thickness. Finally, the calculation of mean absolute error between predicted and ground truth RNFL thickness was performed.

Based on the testing database, SD-OCT segmentation had an average dice similarity coefficient of 0.91, and thickness estimation had a mean absolute error of 2.23 ± 2.1 μm. As compared to conventional OCT software algorithms, deep learning predictions were better correlated with the best available estimate during the test period (r2 = 0.99 vs r2 = 0.88, respectively; P < 0.001).

Our experimental results demonstrate effective and precise segmentation of the RNFL layer with the coefficient of 0.91 and reliable thickness prediction with MAE 2.23 ± 2.1 μm in SD-OCT B-scans. Performance is comparable with human annotation of the RNFL layer and other algorithms according to the correlation coefficient of 0.99 and 0.88, respectively, while artifacts and errors are evident.

 Three-thirds of people with radiologically isolated syndrome (RIS) develop multiple sclerosis (MS) within five years following their first brain magnetic resonance imaging (MRI). Subclinical applications of optical coherence tomography (OCT) include measuring the thickness of different retinal layers and monitoring the progression of visual pathway atrophy and neurodegeneration in relation to the progress of the entire brain.

 Our OCT study was conducted in individuals with RIS to evaluate the thickness of the macular retinal nerve fiber layer (mRNFL) and the retinal ganglion cell layer (RGCL).

 In this study, 22 patients with RIS and 23 healthy individuals healthy control (HC) were enrolled. The control group and the RIS subjects underwent retinal imaging with OCT.

 Total mRNFL thickness was 110.34 ± 13.71 μm in the RIS patients and 112.10 ± 11.23 μm in the HC group. Regional analysis of the mRNFL showed that the difference in thickness was more prominent in the superior quadrant. In regards to ganglion cell layer (GCL)++ thickness, the RIS and HCs population showed statistically significant differences in the nasal (P = 0.041), inferior (P = 0.040), and superior (P = 0.045) quadrants. The nasal (P = 0.041) quadrant showed the highest reduction in thickness compared to other regions of the GCL++. Meanwhile, no significant reduction was seen in GCL+ thickness (P-value > 0.05). When the thickness of the retinal layer of the right eye was compared to that of the left eye of the RIS group, no statistically significant differences were found (P-value > 0.05).

 Compared to the control group, the RIS group had a lower mean thickness of mRNFL and GCL++, indicating retinal neuroaxonal loss.

To clarify the difference of retinal nerve fiber layer (RNFL) thicknesses between patients with retinitis pigmentosa (RP) and normal subjects.

The study included right eyes of 30 patients with non-late-stage RP, which had a waxy pallor in OD, attenuation in retinal arterioles, and midperipheral bone spicule pigmentary changes. To compare the RNFL analysis with normal subjects, the right eyes of 30 age- and gender-matched healthy subjects were included as a control group.

There were no differences between the RP and control groups in terms of demographic and baseline characteristics (P > 0.05, for all). The mean temporal quadrant RNFL thickness was 102.9 ± 31.7 μm (43–222) in the RP group and 72.4 ± 11.8 μm (51–90) in the control group (P < 0.001). The mean nasal quadrant RNFL thickness was 57.6 ± 33.7 μm (21–140) in the RP and 75.0 ± 14.1 μm (56–132) in the control group (P < 0.001). There were no significant RNFL thickness differences between the groups in other sectors and globally (P > 0.05, for all). There was no significant correlation between temporal RNFL thickening and ageing (r = −0.136, P = 0.196) while there was a significant correlation between nasal RNFL thinning and ageing (r = −0.274, P = 0.047).

RNFL is thicker in temporal quadrants and thinner in nasal quadrants in non-late stage RP. Age-related decreases in RNFL thickness occurred earlier in the nasal quadrant and RNFL thickening in the temporal quadrant occurred earlier than this global thinning.

Multiple Sclerosis (MS) is a neurological disease in which demyelination and axonal loss leads to progressive disability. Cognition impairment is among the most common complication. Studying axonal loss in the retina is a new marker for MS. The main goal of our study is to search for correlations between magnetic resonance imaging (MRI) findings and the retinal nerve fiber layer (RNFL) thickness at the macula and head of the optic nerve and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Scores that assess multiple domains of intelligence, and to explore the relationship between changes in the RNFL thickness with intellectual and cognitive dysfunction.

A prospective cross-sectional study was conducted at the University Hospital of Kashani, Isfahan, Iran, from September to December 2013. All patients were assessed with a full-scale intelligence quotient (IQ) on the WAIS-R. An optical coherence tomography study and brain MRI were performed in the same week for all the patients. Statistical analysis was conducted by using a bivariate correlation, by utilizing SPSS 20.0. A P value ≤ 0.05 was the threshold of statistical significance.

Examination of a 100 patients showed a significant correlation between the average RNFL thickness of the macula and the verbal IQ (P value = 0.01) and full IQ (P value = 0.01). There was a significant correlation between brain atrophy and verbal IQ.

The RNFL loss was correlated with verbal IQ and full IQ.

To examine the relationship between retinal nerve fiber layer (RNFL) measurements obtained using scanning laser polarimetry with variable corneal compensation (VCC) and central corneal thickness (CCT) measurements using pentacam in myopic patients

The study included 45 eyes from 45 myopic patients with intraocular pressure (IOP) measurements≤21 mmHg. All participants had normal optic discs and normal standard automated perimetry visual fields. All patients underwent imaging with the GDx VCC and pentacam. We examined the relationship between GDx VCC RNFL measurements and CCT.

Mean spherical equivalent (SE) was -3.65±1.1 D (range: -1.00 to -6.5 D). Mean CCT was 530.9±24.32 µm with a range of 488 to 596 µm. TSNIT (temporal, superior, nasal, inferior, temporal) average, inferior average, superior average, TSNIT standard deviation (SD) and nerve fiber indicator (NFI) were not correlated with CCT. There were no correlations between RNFL thickness and refraction, age, corneal volume and mean keratometry. However, RNFL in patients with CCT≤530 µm was significantly thinner than in those with thick corneas.

RNFL measurements obtained using GDx VCC may not correlate with corneal thickness (CCT) and refraction in myopic patients. Myopic patients with CCT≤530 have thinner RNFL than in those with thick corneas.