Fourier-domain Optical Coherence Tomography Measurements Research Articles

Macula and optic disk features in methamphetamine and crystal methamphetamine addicts using optical coherence tomography.

Methamphetamine and crystal methamphetamine abusers were compared with healthy subjects using optical coherence tomography to assess their retinal nerve fiber layer, macula, and optic disk characteristics. Forty-one methamphetamine and crystal methamphetamine abusers and 42 healthy subjects (mean ± SD of age: 35.82 ± 8.6 and 37.76 ± 9.1years, respectively) were incorporated in this cross-sectional study. The drug abusers had a history of at least five years of substance use through smoking. Fourier-domain optical coherence tomography was used to image and assess the characteristics of retinal nerve fiber layer, macular thickness, and optic disk in the study groups. The retinal nerve fiber layer thickness was significantly lower in the superior and temporal retinal quadrants of drug abusers than healthy subjects (P = 0.008 andP = 0.028, respectively). This study did not find a significant difference between drug abusers and healthy controls regarding optic to disk ratio, rim area, and disk area (P > 0.05). The comparison between the study groups showed that the reductions in perifovea and the superior quadrant of parafoveal thickness were statistically significant (P < 0.001 andP = 0.029, respectively). Fourier-domain optical coherence tomography measurements showed that the retinal nerve fiber layer and macular thickness were different between methamphetamine and crystal methamphetamine abusers and healthy subjects, which should be considered in clinical practice. It seems that these drug abuses can cause alterations in retinal morphology.

Use of Fourier-domain OCT to detect retinal nerve fiber layer degeneration in Parkinson's disease patients.

To demonstrate axonal loss in the retinal nerve fiber layer (RNFL) of patients with Parkinson's disease (PD) and to evaluate the ability of Fourier-domain optical coherence tomography (OCT) to detect RNFL degeneration and retinal thinning in these patients. PD patients (n=100) and healthy subjects (n=100) were included in the study and underwent visual acuity, color vision, and OCT examinations using two next-generation Fourier-domain devices (Spectralis and Cirrus). Differences in the RNFL thicknesses were compared between patients and controls. RNFL thicknesses were significantly reduced in PD patients compared with healthy subjects, especially those obtained using the Spectralis OCT, in the inferotemporal quadrant (155.6±16.5 μm in healthy eyes vs 142.1±24.9 μm in patients, P=0.040) and in the superotemporal quadrant (142.6±20.9 μm in healthy eyes vs 132.77±18.6 μm in PD patients, P=0.046). Significant differences were observed between controls and patients in relation to mean macular thickness (P=0.031), foveal thickness (P=0.030), and inferior outer thickness (P=0.019). PD is associated with RNFL loss and retinal thinning, which is detectable by Fourier-domain OCT measurements.

Correlation between multifocal pattern electroretinography and Fourier-domain OCT in eyes with temporal hemianopia from chiasmal compression

To evaluate the correlation between multifocal pattern electroretinography (mfPERG) and Fourier-domain optical coherence tomography (FD-OCT) with regard to macular and retinal nerve fiber layer (RNFL) thickness in eyes with temporal hemianopia from chiasmal compression. Twenty-five eyes from 25 patients with permanent temporal visual field defects from chiasmal compression and 25 healthy eyes were submitted to mfPERG using a stimulus pattern of 19 rectangles, standard automated perimetry and FD-OCT measurements. The mfPERG response was determined for groups of three rectangles for the nasal and temporal hemifields and for each quadrant. Macular thickness measurements were registered according to an overlaid OCT-generated checkerboard with 36 checks and averaged for the central area, and for each scanned quadrant and hemifield. RNFL thickness was determined for all twelve 30-degree segments around the disc, and averaged for the segments corresponding to the 6, 7, 8, 9, 10, 11 and 12 o'clock position. Correlations were verified with Pearson's correlation coefficients and linear regression analysis. Both mfPERG amplitudes and OCT measurements were significantly smaller in eyes with temporal visual field defects than in normals. A significant and strong correlation was found between most mfPERG and macular or RNFL thickness OCT parameters. mfPERG amplitudes and OCT measurements are significantly correlated in patients with chiasmal compression. Both technologies can quantify neuronal loss and, if used in combination, may help clarify structure-function relationships in this patient population.

In vitro validation of new Fourier-domain optical coherence tomography

To validate the accuracy and evaluate the intra- and inter-observer variability of vascular measurements using novel Fourier-domain optical coherence tomography (FD-OCT) versus intravascular ultrasound (IVUS) in a coronary phantom model. A dedicated cylindrical phantom comprised of four sections with differing dimensions was used to compare images generated by five FD-OCT and five IVUS catheters. Each FD-OCT catheter was tested using three different consoles, generating 15 imaging pullbacks. Two independent experts, blinded to the phantom data, performed measurements. There were 180 FD-OCT and 60 IVUS cross-sectional measurements of mean lumen diameter (MeanLD), minimal lumen diameter (MLD), maximum lumen diameter (MaxLD) and lumen area (LA) at three points in each section. FD-OCT measurements had excellent correlations with IVUS (concordance correlation coefficient [CCC]: ≥0.9769 for MeanLD, LA or longitudinal length [LL]) and phantom dimensions (CCCs for FD-OCT: ≥0.9958 for MeanLD, LA or LL). FD-OCT measurements were larger than IVUS (p<0.0001), but showed less measurement errors compared to IVUS (p<0.0001). Moreover, FD-OCT caused less discrepancy between MaxLD and MLD versus IVUS (p<0.0001). Intra- and inter-observer variability was low for both FD-OCT (CCCs for MeanLD, LA and LL ≥0.9996) and IVUS (≥0.9935). Image catheter position did not influence FD-OCT measurements. FD-OCT was more accurate than IVUS and had similar high reproducibility to determine vascular dimensions in vitro. These results support the use of FD-OCT in the clinical setting.

Combined Impedance Spectroscopy and Fourier Domain Optical Coherence Tomography to Monitor Cells in Three-Dimensional Structures

Objectives To assess non-invasively and in real time the three- dimensional organization of cells within porous matrices by combining Fourier Domain Optical Coherence Tomography (FDOCT) and Impedance Spectroscopy (IS). Materials and Methods Broadband interferences resulting from the recombination of in-depth light scattering events within the sample and light from a reference arm are measured as a modulation of the spectrum generated by a superluminescent laser diode (λo = 930nm, FWHM 90nm). Fourier transform allows in-depth localization of the scatterers, and the 3D microstructure of the sample is reconstructed by raster scanning. Simultaneously impedance spectroscopy is performed with a dielectric probe connected to an impedance analyzer to gather additional cellular information, and synchronized with FDOCT measurements. Results A combined IS-FDOCT system allowing an axial resolution of 5 micrometer in tissues and impedance measurements over the range 20MHz-1GHz has been developed. Alginate matrices have been characterized in terms of microstructure and impedance. Matrices seeded with adipose-derived stem cells have been monitored without the use of labeling agent. Conclusions We have developed a multimodality system that will be instrumental to non-invasively monitor changes in total cell volume fraction and infer cell-specific dielectric properties in 3D structure.

Detection of Macular Ganglion Cell Loss in Glaucoma by Fourier-Domain Optical Coherence Tomography

To map ganglion cell complex (GCC) thickness with high-speed Fourier-domain optical coherence tomography (FD-OCT) and compute novel macular parameters for glaucoma diagnosis. Observational, cross-sectional study. One hundred seventy-eight participants in the Advanced Imaging for Glaucoma Study, divided into 3 groups: 65 persons in the normal group, 78 in the perimetric glaucoma group (PG), and 52 in the preperimetric glaucoma group (PPG). The RTVue FD-OCT system was used to map the macula over a 7 x 6 mm region. The macular OCT images were exported for automatic segmentation using software we developed. The program measured macular retinal (MR) thickness and GCC thickness. The GCC was defined as the combination of nerve fiber, ganglion cell, and inner plexiform layers. Pattern analysis was applied to the GCC map and the diagnostic powers of pattern-based diagnostic parameters were investigated. Results were compared with time-domain (TD) Stratus OCT measurements of MR and circumpapillary nerve fiber layer (NFL) thickness. Repeatability was assessed by intraclass correlation, pooled standard deviation, and coefficient of variation. Diagnostic power was assessed by the area under the receiver operator characteristic (AROC) curve. Measurements in the PG group were the primary measures of performance. The FD-OCT measurements of MR and GCC averages had significantly better repeatability than TD-OCT measurements of MR and NFL averages. The FD-OCT GCC average had significantly (P = 0.02) higher diagnostic power (AROC = 0.90) than MR (AROC = 0.85 for both FD-OCT and TD-OCT) in differentiating between PG and normal. One GCC pattern parameter, global loss volume, had significantly higher AROC (0.92) than the overall average (P = 0.01). The diagnostic powers of the best GCC parameters were statistically equal to TD-OCT NFL average. The higher speed and resolution of FD-OCT improved the repeatability of macular imaging compared with standard TD-OCT. Ganglion cell mapping and pattern analysis improved diagnostic power. The improved diagnostic power of macular GCC imaging is on par with, and complementary to, peripapillary NFL imaging. Macular imaging with FD-OCT is a useful method for glaucoma diagnosis and has potential for tracking glaucoma progression.