Analysis of retinal nerve fiber layer and optic nerve head in glaucoma with different reference plane offsets, using optical coherence tomography.
(57/2999)
PURPOSE: To evaluate the performance of retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters analyzed with different offsets of reference plane in detecting early glaucomatous changes and in correlation with visual function using optical coherence tomography (OCT). METHODS: This was a cross-sectional study consisting of 41 normal subjects and 30 with early and 40 with advanced glaucoma. RNFL thickness and ONH parameters were measured with reference planes positioned at 95, 150, and 205 microm above the level of retinal pigment epithelium (RPE). Discriminating power for early glaucoma detection and correlation with visual field MD for each parameter at different levels of reference plane were compared by using the analyses of area under the receiver operating characteristic curves (AUCs) and linear regression, respectively. RESULTS: All ONH measurements were significantly different between normal and glaucoma groups, irrespective of the level of reference plane. In normal eyes, changing the reference plane position resulted in significant differences in ONH measurements. Among all the parameters examined, integrated rim volume and RNFL thickness measured at 150 microm above the RPE showed the largest AUC (0.966) for early glaucoma detection, and the strongest correlation with visual function (r = 0.793), respectively. CONCLUSIONS: OCT analysis of the ONH and RNFL is useful for early glaucoma detection. Among the three reference planes examined in this study, measurements analyzed at 150 microm above the RPE demonstrated the best performance for glaucoma detection and correlation with visual function. Compared with ONH measurements, RNFL thickness may be a better indicator, reflecting retinal ganglion cell function and monitoring disease progression. (+info)
Use of optical coherence tomography to assess variations in macular retinal thickness in myopia.
(58/2999)
PURPOSE: To investigate the variation in macular retinal thickness in otherwise normal young Asian myopic subjects by using optical coherence tomography (OCT). METHODS: One hundred thirty ophthalmically normal men 19 to 24 years of age with myopia (spherical equivalent, -0.25 to -14.25 D) underwent examination of one randomly selected eye. Visual acuity, refraction, slit lamp examination, applanation tonometry, gonioscopy, A-scan ultrasound, fundus examination, visual field testing, and optic disc photography were performed. Exclusion criteria were visual acuity worse than 20/30, previous intraocular surgery, intraocular pressure >21 mm Hg, or other ocular diseases. Three horizontal transfixation and three vertical transfixation OCT scans (ver.4.1; Carl Zeiss Meditec, Dublin, CA) of 6 mm each were conducted on each eye by a single operator. Neurosensory retinal thicknesses at 100 points along each scan were measured, and the overall average, maximum, and minimum retinal thicknesses were analyzed by simple linear regression and analysis of variance. RESULTS: The average macular retinal thickness (overall) was 230.9 +/- 10.5 microm and was not significantly related to the degree of myopia. The mean maximum retinal thickness (at the parafovea) was 278.4 +/- 13.0 microm, and correlated negatively with axial length (P = 0.03). The mean minimum retinal thickness (at the foveola) was 141.1 +/- 19.1 microm, and this was positively correlated with axial length (P = 0.015) and spherical equivalent (P = 0.0002). The retina was thicker at the superior and nasal parafovea compared to the inferior or temporal parafovea. CONCLUSIONS: Average retinal thickness of the macula does not vary with myopia. However, the parafovea was thinner and the fovea thicker with myopia. (+info)
Objective analysis of retinal damage in HIV-positive patients in the HAART era using OCT.
(59/2999)
PURPOSE: To assess retinal nerve fiber layer (RNFL) thickness in patients with human immunodeficiency virus (HIV) disease without cytomegalovirus retinitis (CMV). DESIGN: A case-control study. METHODS: The study included 113 eyes of 65 patients in one center. Thickness of RNFL along a 3.4-mm-diameter circle centered on the optic nerve head was evaluated using third-generation optical coherence tomography. Patients in group A (39 eyes of 22 patients) were human immunodeficiency virus-negative control subjects. Group B (36 eyes of 18 patients) was composed of HIV patients with no history of CMV retinitis and CD4 counts consistently above 100. Group C (38 eyes of 25 patients) comprised HIV patients with no history of CMV retinitis but a history of CD4 count less than 100 at some point lasting for at least 6 months. RESULTS: The average RNFL thicknesses in groups A, B, and C were 103.33 +/- 8.50 microm, 103.30 +/- 9.28 microm, and 90.10 +/- 12.50 microm, respectively. Group C had significantly thinner overall RNFL than either of the groups A and B (Tukey-Kramer). This difference was most prominent in temporal, superior, and inferior retinal areas. No difference was in nasal retinal area, nor between groups A and B in any of the areas. CONCLUSIONS: Significant RNFL thinning occurs in HIV patients without CMV retinitis and with low CD4 counts compared with the same subgroup of patients with CD4 count increased to above 100 and HIV-negative control subjects. Third-generation OCT may be useful in diagnosis of early subclinical HIV-associated visual functional loss. (+info)
Optical coherence tomography: a new method to assess aneurysm healing.
(60/2999)
OBJECT: Aneurysmal subarachnoid hemorrhage affects approximately 10/100,000 people per year. Endovascular coil embolization is used increasingly to treat cerebral aneurysms and its safety and durability is rapidly developing. The long-term durability of coil embolization of cerebral aneurysms remains in question; patients treated using this modality require multiple follow-up angiography studies and occasional repeated treatments. METHODS: Optical coherence tomography (OCT) is an emerging imaging modality that uses backscattered light to produce high-resolution tomography of optically accessible biological tissues such as the eye, luminal surface of blood vessels, and gastrointestinal tract. Vascular OCT probes in the form of imaging microwires are presently available--although not Food and Drug Administration-approved--and may be adapted for use in the cerebral circulation. In this study the authors describe the initial use of OCT to make visible the neck of aneurysms created in a canine model and treated with coil embolization. Optical coherence tomography images demonstrate changes that correlate with the histological findings of healing at the aneurysm neck and thus may be capable of demonstrating human cerebral aneurysm healing. CONCLUSIONS: Optical coherence tomography may obviate the need for subsequent follow-up angiography studies as well as aid in the understanding of endovascular tissue healing. Data in this study demonstrate that further investigation of in vivo imaging with such probes is warranted. (+info)
High-resolution optical coherence tomographic imaging of osteoarthritic cartilage during open knee surgery.
(61/2999)
This study demonstrates the first real-time imaging in vivo of human cartilage in normal and osteoarthritic knee joints at a resolution of micrometers, using optical coherence tomography (OCT). This recently developed high-resolution imaging technology is analogous to B-mode ultrasound except that it uses infrared light rather than sound. Real-time imaging with 11-microm resolution at four frames per second was performed on six patients using a portable OCT system with a handheld imaging probe during open knee surgery. Tissue registration was achieved by marking sites before imaging, and then histologic processing was performed. Structural changes including cartilage thinning, fissures, and fibrillations were observed at a resolution substantially higher than is achieved with any current clinical imaging technology. The structural features detected with OCT were evident in the corresponding histology. In addition to changes in architectural morphology, changes in the birefringent or the polarization properties of the articular cartilage were observed with OCT, suggesting collagen disorganization, an early indicator of osteoarthritis. Furthermore, this study supports the hypothesis that polarization-sensitive OCT may allow osteoarthritis to be diagnosed before cartilage thinning. This study illustrates that OCT, which can eventually be developed for use in offices or through an arthroscope, has considerable potential for assessing early osteoarthritic cartilage and monitoring therapeutic effects for cartilage repair with resolution in real time on a scale of micrometers. (+info)
Correlation between retinal nerve fibre layer thickness and optic nerve head size: an optical coherence tomography study.
(62/2999)
AIM: To investigate the correlation between retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) size in normal white subjects by means of optical coherence tomography (OCT). METHODS: 54 eyes of 54 healthy subjects aged between 15 and 54 underwent peripapillary RNFL thickness measurement by a series of three circular scans with a 3.4 mm diameter (Stratus OCT, RNFL Thickness 3.4 acquisition protocol). ONH analysis was performed by means of six radial scans centred on the optic disc (Stratus OCT, Fast Optic Disc acquisition protocol). The mean RNFL values were correlated with the data obtained by ONH analysis. RESULTS: The superior, nasal, and inferior quadrant RNFL thickness showed a significant correlation with the optic disc area (R = 0.3822, p = 0.0043), (R = 0.3024, p = 0.026), (R = 0.4048, p = 0.0024) and the horizontal disc diameter (R = 0.2971, p = 0.0291), (R = 0.2752, p = 0.044), (R = 0.3970, p = 0.003). The superior and inferior quadrant RNFL thickness was also positively correlated with the vertical disc diameter (R = 0.3774, p = 0.0049), (R = 0.2793, p = 0.0408). A significant correlation was observed between the 360 degrees average RNFL thickness and the optic disc area and the vertical and horizontal disc diameters of the ONH (R = 0.4985, p = 0.0001), (R = 0.4454, p = 0.0007), (R = 0.4301, p = 0.0012). CONCLUSIONS: RNFL thickness measurements obtained by Stratus OCT increased significantly with an increase in optic disc size. It is not clear if eyes with large ONHs show a thicker RNFL as a result of an increased amount of nerve fibres or to the shorter distance between the circular scan and the optic disc edge. (+info)
In vivo characterization of coronary atherosclerotic plaque by use of optical coherence tomography.
(63/2999)
BACKGROUND: The current understanding of the pathophysiology of coronary artery disease is based largely on postmortem studies. Optical coherence tomography (OCT) is a high-resolution ( approximately 10 microm), catheter-based imaging modality capable of investigating detailed coronary plaque morphology in vivo. METHODS AND RESULTS: Patients undergoing cardiac catheterization were enrolled and categorized according to their clinical presentation: recent acute myocardial infarction (AMI), acute coronary syndromes (ACS) constituting non-ST-segment elevation AMI and unstable angina, or stable angina pectoris (SAP). OCT imaging was performed with a 3.2F catheter. Two observers independently analyzed the images using the previously validated criteria for plaque characterization. Of 69 patients enrolled, 57 patients (20 with AMI, 20 with ACS, and 17 with SAP) had analyzable images. In the AMI, ACS, and SAP groups, lipid-rich plaque (defined by lipid occupying > or =2 quadrants of the cross-sectional area) was observed in 90%, 75%, and 59%, respectively (P=0.09). The median value of the minimum thickness of the fibrous cap was 47.0, 53.8, and 102.6 microm, respectively (P=0.034). The frequency of thin-cap fibroatheroma (defined by lipid-rich plaque with cap thickness < or =65 microm) was 72% in the AMI group, 50% in the ACS group, and 20% in the SAP group (P=0.012). No procedure-related complications occurred. CONCLUSIONS: OCT is a safe and effective modality for characterizing coronary atherosclerotic plaques in vivo. Thin-cap fibroatheroma was more frequently observed in patients with AMI or ACS than SAP. This is the first study to compare detailed in vivo plaque morphology in patients with different clinical presentations. (+info)
Comparability of retinal nerve fiber layer thickness measurements of optical coherence tomography instruments.
(64/2999)
PURPOSE: To compare retinal nerve fiber layer (RNFL) measurements between two ocular coherence tomography (OCT) instruments (OCT 2000 and Stratus OCT; Carl Zeiss Meditec, Dublin, CA) and compare their diagnostic precision. METHODS: One hundred thirty-nine consecutive subjects were imaged (3 x 3.4-mm diameter circular scans) on the same day with each instrument. Thirty-five patients were excluded due to poor-quality images. RNFL thicknesses measured by the two instruments were compared, and receiver operating characteristic (ROC) curves were used to determine diagnostic precision. RESULTS: A randomly selected eye of each of 104 participants (28 with open-angle glaucoma, 40 with suspected glaucoma, and 36 healthy subjects) was analyzed. RNFL thickness measurements generally were thicker with OCT 2000 than with Stratus OCT. The difference in global RNFL thickness between instruments was within 20 microm in 66 (65%) of subjects and within 10 microm (the instrument's limit of resolution) in 25 (25%) subjects. Application of a correction factor to OCT 2000 measurements predicted Stratus OCT RNFL thickness within 10 microm of the observed measurement in 75% of the eyes. For both instruments, highest ROC curve areas (better discrimination between glaucomatous and normal eyes) were found in the inferior sector. Discrimination using global RNFL thickness was better with Stratus OCT than OCT 2000 (P = 0.043). CONCLUSIONS: RNFL thickness measurements measured by OCT 2000 can be approximated to measurements made by Stratus OCT using correction factors calculated by this study. However, there remains considerable variability that exceeds the limits of resolution afforded by the instruments themselves. Therefore comparisons between instruments using these approximations should be interpreted with caution. (+info)