Retinal Nerve Fiber Layer Structure Research Articles

Modeling the Chronic Loss of Optic Nerve Axons and the Effects on the Retinal Nerve Fiber Layer Structure in Primary Disorder of Myelin.

PurposeWe determined whether the chronic lack of optic nerve myelination and subsequent axon loss is associated with optical coherence tomography (OCT) changes in the retinal nerve fiber layer (RNFL), and whether this models what occurs in multiple sclerosis (MS) and confers its use as a surrogate marker for axon degeneration.MethodsUsing an animal model of Pelizaeus-Merzbacher disease (shp) bilateral longitudinal measurements of the peripapillary RNFL (spectral-domain OCT), electroretinograms (ERG), and visual evoked potentials (VEP) were performed in affected and control animals from 5 months to 2 years and in individual animals at single time points. Light and electron microscopy of the optic nerve and retina and histomorphometric measurements of the RNFL were compared to OCT data.ResultsOf the shp animals, 17% had an average reduction of OCT RNFL thickness on the superior retinal quadrant compared to controls (P < 0.05). Electroretinograms showed normal photopic A- and B-waves but flash VEPs were disorganized in shp animals. Morphologically, the shp retinas and optic nerves revealed significant RNFL thinning (P < 0.001) without retinal ganglion cell (RGC) loss, decrease total and relative retinal axonal area, and loss of optic nerve axons. There was strong positive correlation between OCT and morphometric RNFL thickness measurements (r = 0.878, P = 0.004).ConclusionThe loss of optic nerve axons demonstrated in the shp model resulted in moderate thinning of the RNFL confirmed by OCT and histology. These results indicate that OCT-derived RNFL measurement can be a useful surrogate biomarker of optic nerve axon loss and potentially disease progression in demyelinating diseases.

Retinal nerve fiber layer structure abnormalities in patients with Neuro-Behcet's disease.

Our aim was the evaluation of retinal nerve fiber layer (RNFL) and central macular thickness (CMT) in patients with Neuro-Behcet's disease (NBD) and to compare the results with healthy control subjects. We recruited 50 eyes of 25 patients with NBD and 42 eyes of 21 age-matched healthy control subjects. Patients and control subjects underwent a thorough ophthalmic examination, including retinal nerve fiber layer and macular thickness measurements by optical coherence tomography. No significant difference was found between groups for age, sex, intra-ocular pressure and central corneal thickness measurements. The average RNFL in patients with NBD was significantly lower than that of healthy controls (86.92 ± 18.36 μm vs. 99.74 ± 8.73 μm; p = 0.00). There was significant thinning of the RNFL in three of four quadrants of the peripapillary area, superior (107.22 ± 30.91 μm vs. 125.57 ± 20.97 μm; p = 0.00), inferior (110.36 ± 25.57 μm vs. 132.19 ± 12.71 μm; p = 0.00) and nasal (68.84 ± 18.47 μm vs. 74.98 ± 11.42 μm; p = 0.05), in patients with NBD. Average CMT was significantly lower in NBD patients than in control subjects (244.06 ± 26.25 μm vs. 261.69 ± 25.71 μm; p = 0.00). There are significant differences in average RNFL and CMT between the two groups. RNFL and CMT thicknesses are reduced in patients with NBD compared with the healthy controls.

Optimizing Structure–Function Relationship by Maximizing Correspondence Between Glaucomatous Visual Fields and Mathematical Retinal Nerve Fiber Models

To introduce a method to optimize structural retinal nerve fiber layer (RNFL) models based on glaucomatous visual field data and to show how such an optimized model can be used to reduce noise in visual fields while probably preserving clinically important features. Correlation coefficients between age-adjusted deviation values of pairs of visual field test locations were calculated from 103 visual fields of eyes with moderate glaucomatous damage. Distances between those test locations were defined for various parameters of a mathematical RNFL model. Then, the correspondence between the structural and functional data was defined by the spread, or variance, of the correlation coefficients for all distances. The model parameters that minimized this spread constituted the optimized model. To reduce noise in visual fields, the optimized model was used to smooth visual field data according to the RNFL's structure. The resulting fields were compared with visual fields that were smoothed based on the regular testing grid. The optimal parameters for the RNFL model reduced the variance of the correlation coefficients by 78% and were well within the range of parameters previously determined from fundus photographs. Smoothing the visual fields based on the optimized RNFL model strongly reduced noise while keeping important features. Mathematic RNFL models can be optimized based on visual field data, resulting in a strong structure-function relationship. Taking the RNFL's shape, as defined by such an optimized model, into account when smoothing visual fields results in better noise reduction while preserving important details.

Comparison of relation between visual function index and retinal nerve fiber layer structure by optical coherence tomography among primary open angle glaucoma and primary angle closure glaucoma eyes.

Purpose:To compare the visual field index (VFI) in primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) eyes, and to study the correlation with disc variables on optical coherence tomography (OCT) in all stages of severity.Materials and Methods:Thirty POAG and PACG underwent Humphrey visual field 24-2 along with detailed examination. They also underwent stratus OCT imaging of the optic nerve and retinal nerve fiber layer (RNFL). The correlation of VFI with RNFL thickness was compared in POAG and PACG.Results:The VFI significantly differed between POAG and PACG, with POAG eyes apparently having a better VFI at all severities of glaucoma. There were statistically significant differences in the superior max (Smax) and inferior max (Imax) in early and moderate POAG and PACG eyes. In early and moderate glaucoma, multivariate regression showed that maximum correlation of the VFI was seen with the mean deviation (b = 1.7, P < 0.001), average and superior RNFL thickness (b = 2.1, P < 0.001 and b = 1.8, P = 0.03, respectively), and age (b = 0.7, P = 0.04); while no correlation was seen with intraocular pressure (IOP), axial length, sex, or other clinical variables. VFI did not correlate well with RNFL thickness or other disc variables on OCT in severe glaucoma.Conclusion:VFI may not serve as a useful indicator of visual function in severe glaucoma. More useful indicators are required to monitor glaucoma patients with severe damage.

Retinal Nerve Fiber Layer Structure Abnormalities in Schizophrenia and Its Relationship to Disease State: Evidence From Optical Coherence Tomography

We determined structural retinal nerve fiber layer (RNFL) changes in schizophrenia patients and established if the structural changes were related to the duration of the illness using spectral-domain optical coherence tomography (SD-OCT). We recruited a total of 30 schizophrenic patients and 30 age-matched controls in the study. The schizophrenic patients were subdivided further to acute (n = 5), chronic (n = 13), and long-term chronic (n = 12) subgroups depending on their duration of illness. Using SD-OCT, the peripapillary RNFL thickness, macula thickness, and macula volume measurements of schizophrenic patients and the control subjects were measured and compared at each location. Schizophrenic patients showed a statistically significant reduction in overall peripapillary RNFL thickness (cases, 94.70 ± 9.88 μm; controls, 103.53 ± 6.53 μm; P < 0.001), macula thickness (cases, 269.26 ± 12.59 μm; controls, 284.83 ± 9.76 μm; P < 0.001), and macula volume (cases, 9.61 ± 0.45 mm(3); controls, 10.17 ± 0.35 μm; P < 0.001). Chronic and long-term chronic schizophrenic patients were found to have significant peripapillary RNFL thinning, macula thinning, and reduction of macula volume when compared to controls (P < 0.001). There also was a statistically significant reverse correlation (P < 0.05) of peripapillary RNFL thickness (r = -0.36), macula thickness (r = -0.38), and macula volume reduction (r = -0.36) with the duration of schizophrenic illness. These results indicate that RNFL and macula thickness, as well as macula volume measurements are reduced in schizophrenic patients. The degree of thinning and reduction was more significant in the chronic phase of the disease and correlated with the duration of illness. These findings demonstrate that SD-OCT can be a useful tool for the diagnosis and monitoring the progression of this disease.

Retinal nerve fiber layer structure abnormalities in early Alzheimer's disease: Evidence in optical coherence tomography

Alzheimer's disease (AD) patients often have visual disorders which may be due to retinal nerve degenerative changes. The aim of the current study was to determine the thickness changes of retina nerve fibers with optical coherence tomography (OCT) in AD patients. The OCT was used to assess the thickness of retinal nerve fiber layer (RNFL) from 22 AD patients and 22 healthy age-matched controls. The corrected visual acuity and intraocular pressure were measured and the dilated fundus examination and fundus image acquisition were also performed in those subjects. Compared with healthy age-matched controls, the RNFL thickness of AD patients were much thinner ( p < 0.05), especially in supra-retina and infra-retina, while no difference was found in the other retinal area. These changes were also confirmed by the fundus images. In conclusion, retinal nerve degeneration is present in the retina of AD patients and this degeneration is likely localized preferentially to the superior and inferior quadrant.

Predicting Visual Function from the Measurements of Retinal Nerve Fiber Layer Structure

To develop and validate a method of predicting visual function from retinal nerve fiber layer (RNFL) structure in glaucoma. RNFL thickness (RNFLT) measurements from scanning laser polarimetry (SLP) and visual field (VF) sensitivity from standard automated perimetry were made available for 535 eyes from three centers. In a training dataset, structure-function relationships were characterized by using linear regression and a type of neural network: radial basis function customized under a Bayesian framework (BRBF). These two models were used in a test dataset to (1) predict sensitivity at individual VF locations from RNFLT measurements and (2) predict the spatial relationship between VF locations and positions at a peripapillary RNFLT measurement annulus. Predicted spatial relationships were compared with a published anatomic structure-function map. Compared with linear regression, BRBF yielded a nearly twofold improvement (P < 0.001; paired t-test) in performance of predicting VF sensitivity in the test dataset (mean absolute prediction error of 2.9 dB [SD 3.7] versus 4.9 dB [SD 4.0]). The predicted spatial structure-function relationship showed better agreement (P < 0.001; paired t-test) with anatomic prior knowledge when the BRBF was compared with the linear regression (median absolute angular difference of 15° vs. 62°). The BRBF generates clinically useful relationships that relate topographical maps of RNFL measurement to VF locations and allows the VF sensitivity to be predicted from structural measurements. This method may allow clinicians to evaluate structural and functional measures in the same domain. It could also be generalized to use other structural measures.

Evaluating the Optic Disc and Retinal Nerve Fiber Layer in Glaucoma II: Optical Image Analysis

Glaucoma is a widespread, blindness-causing disease that is characterized in part by specific and sometimes subtle changes in optic disc and retinal nerve fiber layer topography. Several recently developed computer-based optical imaging techniques allow objective evaluation of the optic disc and retinal nerve fiber layer. These techniques use different optical properties and different properties of the retina to provide micron scale measurements of many aspects of optic disc and retinal nerve fiber layer structure. This article describes and evaluates 3 of these techniques: confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography