Retinal Nerve Fiber Layer Thickness (retinal + nerve_fiber_layer_thickness)

Distribution by Scientific Domains

Selected Abstracts

Retinal nerve fiber layer thickness and central corneal thickness in ocular hypertensive patients and healthy subjects

Purpose To establish the correlation between central corneal thickness (CCT) and retinal nerve fiber layer (RNFL) thickness in ocular hypertensive patients and healthy subjects. Methods We prospectively collected charts of healthy subjects and ocular hypertensive (OHT) patients in one academic center between 2007 and 2008. OHT patients were defined by two measurements of intraocular pressure superior to 21mmHg without treatment, open angle in gonioscopy, normal appearing optic nerve head and normal visual field test Standard Automated Perimetry (SAP SITA) and Frequency Doubling Technique (FDT). Every patient underwent a standard clinical examination including optic nerve head examination, intraocular pressure, CCT measurement by ultrasonic (US) and anterior segment OCT pachymetry, visual field testing (SAP and FDT), RNFL thickness by scanning laser polarimetry (GDX-VCC) and optical coherence tomography (OCT). Results Eighty healthy subjects and 60 OHT patients were included. A correlation between US CCT and OCT CCT was found in both groups (r2=0.85 and r2= 0.87, p<0.001). There was no significant difference (p>0.15) in GDX-VCC and OCT RNFL thickness in both groups. In controls there was no correlation of any RNFL thickness measurement with the CCT. In OHT patients, the US CCT was weakly correlated with the average TSNIT evaluated by GDX-VCC (r2= 0.04, p<0.02). Conclusion This study did not show any relevant correlation between the RNFL thickness evaluated by GDX-VCC and the US CCT in healthy individuals and in OHT patients with a normal FDT. [source]

Longitudinal study of vision and retinal nerve fiber layer thickness in multiple sclerosis

Lauren S. Talman BA
Objective Cross-sectional studies of optical coherence tomography (OCT) show that retinal nerve fiber layer (RNFL) thickness is reduced in multiple sclerosis (MS) and correlates with visual function. We determined how longitudinal changes in RNFL thickness relate to visual loss. We also examined patterns of RNFL thinning over time in MS eyes with and without a prior history of acute optic neuritis (ON). Methods Patients underwent OCT measurement of RNFL thickness at baseline and at 6-month intervals during a mean follow-up of 18 months at 3 centers. Low-contrast letter acuity (2.5%, 1.25% contrast) and visual acuity (VA) were assessed. Results Among 299 patients (593 eyes) with ,6 months follow-up, eyes with visual loss showed greater RNFL thinning compared to eyes with stable vision (low-contrast acuity, 2.5%: p < 0.001; VA: p = 0.005). RNFL thinning increased over time, with average losses of 2.9,m at 2 to 3 years and 6.1,m at 3 to 4.5 years (p < 0.001 vs 0.5,1-year follow-up interval). These patterns were observed for eyes with or without prior history of ON. Proportions of eyes with RNFL loss greater than test-retest variability (,6.6,m) increased from 11% at 0 to 1 year to 44% at 3 to 4.5 years (p < 0.001). Interpretation Progressive RNFL thinning occurs as a function of time in some patients with MS, even in the absence of ON, and is associated with clinically significant visual loss. These findings are consistent with subclinical axonal loss in the anterior visual pathway in MS, and support the use of OCT and low-contrast acuity as methods to evaluate the effectiveness of putative neuroprotection protocols. ANN NEUROL 2010;67:749,760 [source]

3253: Ocular neurovascular coupling in glaucoma patients

Purpose Defining property of glaucoma, cupping of the optic disc in parallel to loss of retinal ganglion cells and their axon, implies tissue remodeling of the optic nerve head which in turns requires involvement of astrocytes. Their malfunction may lead not only to cupping, but also to disturbance in ocular neurovascular coupling. Methods We analyzed 122 glaucoma patients, ocular hypertensives and healthy controls who all received no IOP-lowering therapy at least four weeks prior to the study examination. One eye per subject entered the primary analysis: in the POAG group, an eye with the biggest damage, in the OHT group an eye with the highest average IOP was selected. Relative vessel diameter increase in response to flicker light was used as the measure of neurovascular coupling. Results This response was impaired in untreated POAG patients, affecting both superior and inferior temporal retinal vessels. In general, inferior vessel dilated more than superior ones. The dilation amplitude was inversely correlated to the level of morphological (retinal nerve fiber layer thickness) and functional (visual field mean defect) glaucomatous damage. Despite the relatively high level of inter- and intraocular correlation of vessel responses, in a separate analysis of contralateral eyes, they seem to display higher dilation amplitudes than the more damaged eyes which were included in the original analysis. Conclusion Neurovascular coupling is impaired in untreated glaucoma patients. Prospective studies are underway in an attempt to clarify the cause versus consequence relationship between the glaucomatous damage and disturbance of neurovascular coupling. [source]

2453: Optic disc in the picture: novel imaging techniques

Purpose Advances in light sources and detection technologies enabled a paradigm shift in retinal OCT imaging performance. ,Snap-shot OCT' enabling isotropic sampling over 512x512x1024 voxels with 600 frames/second in less than a second is now possible. Methods The resolution advantage in conjunction with full volumetric sampling has enabled the development of more informative indices of axonal damage in glaucoma compared with measurements of RNFL thickness and cup to disc ratio provided by other devices. A novel mapping method was developed, the three-dimensional minimal distance (3D-MDM) as the optical correlate of true retinal nerve fiber layer thickness around the optic nerve head region. In a preliminary study relation between the cross-sectional areas of the retinal nerve fiber layer and the optic nerve was found to be a sensitive measure of axon loss. Results In addition to all the major layers of the retina, the entire choroid down to the lamina cribrosa and sclera can now be visualized. This enables unprecedented information about choroidal vasculature without any contrast agents, choroidal thickness and will enable quantification of choroidal blood flow in the near future. Furthermore this technique allows tissue to be imaged in vitro with an image resolution better than 1-2 m, allowing to image single cells and detect pre-apoptotic signatures using OCT. RGC-5 cells were imaged using a sampling rate 1024x512x1024 voxel at 800 nm central wavelength and a bandwidth of 230 nm, enabling the detection of optical signatures at different pre-stages of programmed cell death. Conclusion Significantly increased OCT imaging speed and tissue penetration might enable novel insights and diagnostic opportunities in the diagnosis and therapy monitoring of glaucoma. Commercial interest [source]

4353: Comparison of diagnostic accuracy of Fourier-domain optical coherence tomography and scanning laser polarimetery to detect glaucoma

Purpose To compare diagnostic accuracy of retinal nerve fiber layer thickness (RNFLT) measurements made using RTVue-100 Fourier-domain optical coherence tomography (RTVue-OCT) and scanning laser polarimetry with variable (GDx-VCC) or enhanced compensation (GDx-ECC). Methods One eye of each of 177 consecutive patients was imaged. Healthy (n=50) and ocular hypertensive (n=28) eyes were defined as normal, preperimetric (n=33) perimetric (n=66) glaucoma eyes as diseased. Results For average RNFLT sensitivity was higher (Chi-square test, p=0.002) with RTVue-OCT (65.7 %) than with GDx-VCC (49.5 %). For superior and inferior RNFLT sensitivity was similar with all methods. For the different nerve fiber bundle parameters, sensitivity of RTVue-OCT (64.6 to 84.8 %) was consistently, up to 35 % higher (p<0.001) than that of GDx-VCC/ECC (28.3 to 72.7 %). Specificity ranged 84.6 to 98.7 % with RTVue-OCT, 92.3 to 100 % with GDx-VCC, and 94.9 to 100 % with GDx-ECC, with no significant difference between the methods except for one nerve fiber bundle parameter, for which RTVue-OCT was less specific than either GDx method (p,0.004). Diagnostic accuracy of the GDx-VCC/ECC nerve fiber indicator (NFI) and RTVue-OCT average RNFLT were similar. Of the detected glaucoma cases 87.7 % was identified both by GDx-VCC/ECC NFI and average RNFLT of RTVue-OCT. Conclusion In this clinical setting, all methods were similarly highly specific, but for localized RNFLT damage RTVue-OCT was statistically and clinically significantly more sensitive than GDx-VCC and GDx-ECC. Most detected glaucoma cases were identified with all three methods. Commercial interest [source]

RTVue Fourier-domain OCT: reproducibility of RNFLT and macular thickness measurements

Purpose To evaluate the reproducibility of peripapillary retinal nerve fiber layer thickness (RNFLT) and macular thickness (MT) measurements with the RTVue-100 Fourier-domain optical coherence tomography, and to determine the influence of pupil dilation, patients' experience in examinations and severity of glaucoma. Methods One eye of 14 normal subjects, 11 patients with moderate, 12 patients with severe glaucoma and 40 screening trial participants were imaged 5 times on the same day. For the hospital-based patients, the measurement series was repeated after pupil dilation and 3 months later. Results For the RNFLT and the MT parameters, intrasession intraclass correlation coefficient (ICC) varied between 93.9 and 99.0%, intrasession coefficient of variation (CV) between 1.95 and 5.69 %, and intratest variability between 3.11 and 9.13 m. Most thickness values, all intrasession CV and intratest variability values and the signal strength index remained unchanged after pupil dilation. Most intrasession CV values increased significantly with increasing disease severity. Patients' experience in imaging examinations had no influence on intrasession CV. Intratest variability and intrasession CV represented 79.1 to 98.6 % and 77.1 to 95.0 % of test-retest variability and intervisit CV, respectively. Conclusion Reproducibility of RNFLT and MT measurement with the RTVue-100 OCT are satisfactory for clinical purposes both in normals and glaucoma patients. Pupil dilation and patients' experience in imaging examinations do not influence the reproducibility of the measurements clinically significantly. Commercial interest [source]

Toxic effect of vigabatrin on retinal nerve fiber layer

Purpose To investigate whether peripheral and central visual field defects detected among epilepsy patients treated with vigabatrin are associated with reduced peripapillary retinal nerve fiber layer thickness as measured with optic coherence tomography (OCT). Methods Nine epilepsy patients with vigabatrin-attributed visual field loss (group 1) and seven patients(age and sex matched) with epilepsy treated with other drugs(control group 2) were regularly examined with automated perimetry up to 60 degrees from fixation point (Humphrey Field Analyser). Peripapillary retinal nerve fiber layer thickness (RNFLT) was quantified by optic coherence tomography (OCT) using Fast RNFLT protocol, Stratus OCT (3.0). Five of the patients in group 1 had peripheral visual field defects, (group 1a), four had a central field defect(group 1b). All patients in control group 2 had normal visual field. Results Patients with vigabatrin-attributed visual field loss had attenuated total RNFLT compared to controls (right eye : mean total RNFLT: group 1: 75.6 m (SD 12.7); group 2: 103.5 m (SD 9.7), mean difference 27.9 m (CI 15.9-39.9;P < 0.001). The nasal and inferior sectors RNFLT were more attenuated in patients with vigabatrin-attributed visual field loss compared to controls, while no difference was detected in the temporal RNFLT. Both individuals with peripheral and central visual field losses had attenuated mean total RNFLT compared to controls (P = 0.006 and P= 0.002, respectively). Conclusion Vigabatrin-attributed visual field defects are associated with reduced RNFLT. Combination of perimetry and OCT can efficiently detect vigabatrin induced retinal nerve fiber damage. [source]

An evaluation of the retinal nerve fiber layer thickness by scanning laser polarimetry in individuals with dementia of the Alzheimer type

Hlne Kergoat
ABSTRACT. Purpose: To determine, using scanning laser polarimetry, whether or not the retinal nerve fiber layer (RNFL) is altered in dementia of the Alzheimer type (DAT). Methods: Thirty individuals with mild to moderate DAT and 30 healthy age-matched controls participated in the study. Fundus images were acquired with a Nerve Fiber Analyzer. RNFL thickness measurements were obtained under an ellipse located 1.75 disc diameter from the optic nerve head (ONH) center. Results: No differences in RNFL thickness were observed between DAT and healthy subjects. The regional distribution of RNFL thickness was similar between the two test groups, with the RNFL being thickest in the superior and inferior retinal segments relative to the nasal and temporal regions. Conclusions: Our data indicate that the RNFL is not altered in DAT, at least in the earlier stages of the disease. [source]