Extended scan depth optical coherence tomography for evaluating ocular surface shape.
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ABSTRACT:
SUBMITTER: Shen M
PROVIDER: S-EPMC3107837 | biostudies-other | 2011 May
REPOSITORIES: biostudies-other
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Project description:PurposeTo measure by ultralong scan depth optical coherence tomography (UL-OCT) dimensional changes in the anterior segment of human eyes during accommodation.DesignEvaluation of diagnostic test or technology.ParticipantsForty-one right eyes of healthy subjects with a mean age of 34 years (range, 22-41 years) and a mean refraction of -2.5 ± 2.6 diopters were imaged in 2 repeated measurements at minimal and maximal accommodations.MethodsA specially adapted and designed UL-OCT instrument was used to image from the front surface of the cornea to the back surface of the crystalline lens. Custom software corrected the optical distortion of the images and yielded the biometric measurements. The coefficient of repeatability and the intraclass correlation coefficient were calculated to evaluate the repeatability and reliability.Main outcome measuresAnterior segment parameters and associated repeatability and reliability upon accommodation. The dimensional results included central corneal thickness (CCT), anterior chamber depth and width (ACD, ACW), pupil diameter (PD), lens thickness (LT), anterior segment length (ASL = ACD + LT), lens central position (LCP = ACD + 1/2LT), and horizontal radii of the lens anterior and posterior surface curvatures (LAC, LPC).ResultsRepeated measurements of each variable within each accommodative state did not differ significantly (P>0.05). The coefficients of repeatability (CORs) and intraclass correlation coefficients for CCT, ACW, ACD, LT, LCP, and ASL were excellent (1.2%- 3.59% and 0.998-0.877, respectively). They were higher for PD (18.90%-21.63% and 0.880-0.874, respectively) and moderate for LAC and LPC (34.86%-42.72% and 0.669-0.251, respectively) in the 2 accommodative states. Compared with minimal accommodation, PD, ACD, LAC, LPC, and LCP decreased and LT and ASL increased significantly at maximal accommodation (P<0.05), whereas CCT and ACW did not change (P>0.05).ConclusionsThe UL-OCT measured changes in anterior segment dimensions during accommodation with good repeatability and reliability. During accommodation, the back surface of the lens became steeper as the lens moved forward.Financial disclosure(s)The authors have no proprietary or commercial interest in any of the materials discussed in this article.
| S-EPMC3505244 | biostudies-literature
Project description:Spectral-domain optical coherence tomography (SD-OCT) has been used to observe the morphology of the palisades of Vogt (POV) with satisfactory resolutions. In this study, we used SD-OCT to examine the microstructure of the POV in ocular surface disorders with limbal involvement. We detect subclinical limbal pathologies based on five parameters, including (1) decreased epithelial thickness, (2) loss of the sharp stromal tip, (3) loss of the smooth epithelial-stromal interface, (4) dilated stromal vessels, and (5) decreased POV density. Eighteen eyes of 10 patients with advancing wavelike epitheliopathy (AWE) and 15 eyes of 9 patients with phlyctenular keratitis/ocular rosacea were recruited. SD-OCT could detect abnormal changes in the POV in 100% of the lesion sites. In presumed-healthy areas of the diseased eyes diagnosed by slit-lamp biomicroscopy, SD-OCT detected abnormal changes in the POV in 100% of the eyes in both groups. In patients with unilateral disease, abnormal changes in the POV were detected by SD-OCT in 50% and 100% of presumed-healthy eyes diagnosed by slit-lamp biomicroscopy in the AWE group and phlyctenular keratitis/ocular rosacea group, respectively. SD-OCT is powerful in detecting POV changes in ocular surface disorders and can provide useful information that cannot be provided by slit-lamp biomicroscopy.
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Project description:PurposeThe aim of the study is to demonstrate that the ocular dynamics of the anterior chamber of the eye can be estimated quantitatively by means of optical coherence tomography (OCT).MethodsA commercial high speed, high resolution optical coherence tomographer was used. The sequences of tomographic images of the iridocorneal angle of three subjects were captured and each image from the sequence was processed in MATLAB environment in order to detect and identify the contours of the cornea and iris. The data on pulsatile displacements of the cornea and iris and the changes of the depth of the gap between them were retrieved from the sequences. Finally, the spectral analysis of the changes of these parameters was performed.ResultsThe results of the temporal and spectral analysis manifest the ocular microfluctuation that might be associated with breathing (manifested by 0.25 Hz peak in the power spectra), heart rate (1-1.5 Hz peak), and ocular hemodynamics (3.75-4.5 Hz peak).ConclusionsThis paper shows that the optical coherence tomography can be used as a tool for noninvasive estimation of the ocular dynamics of the anterior segment of the eye, but its usability in diagnostics of the ocular hemodynamics needs further investigations.
| S-EPMC4628777 | biostudies-literature
Project description:Optical coherence tomography angiography relies on motion for contrast and requires at least two data acquisitions per pointwise scanning location. We present a method termed spectral contrast optical coherence tomography angiography using visible light that relies on the spectral signatures of blood for angiography from a single scan using endogenous contrast. We demonstrate the molecular sensitivity of this method, which enables lymphatic vessel, blood, and tissue discrimination.
| S-EPMC6333625 | biostudies-literature
Project description:PurposeTo study a case with intraretinal Toxocara larvae in a granuloma using high-penetration optical coherence tomography (HP-OCT).MethodsA 50-year-old man, who was referred to our clinic with ocular toxocariasis, initially presented with granuloma formation in the retina. We followed the treatment-associated changes in the toxocariasis lesion by a series of examinations using HP-OCT before and after a systemic corticosteroid and anthelmintic therapy.ResultsThe posterior pole granuloma initially appeared as a yellowish-white intraretinal lesion with an exudative focus and dye leakage seen on angiography. After therapy, the lesion was no longer exudative. During treatment-free periods, an intraretinal lesion was seen protruding from the retinal surface into the vitreous cavity. HP-OCT confirmed the elevated lesion protruding from the retinal surface into the vitreous cavity. With treatment, the protruding focus flattened during the following 8 months, but the lesion recurred after the treatment stopped.ConclusionsThe findings and clinical course strongly suggested ocular toxocariasis. The protruding retinal lesion may have been an ocular manifestation of toxocariasis. HP-OCT was useful in the follow-up and diagnosis.
| S-EPMC3934803 | biostudies-literature
Project description:The human vocal fold (VF) oscillates in multiple vectors and consists of distinct layers with varying viscoelastic properties that contribute to the mucosal wave. Office-based and operative laryngeal endoscopy are limited to diagnostic evaluation of the VF epithelial surface only and are restricted to axial-plane characterization of the horizontal mucosal wave. As such, understanding of the biomechanics of human VF motion remains limited. Optical coherence tomography (OCT) is a micrometer-resolution, high-speed endoscopic imaging modality which acquires cross-sectional images of tissue. Our study aimed to leverage OCT technology and develop quantitative methods for analyzing the anatomy and kinematics of in vivo VF motion in the coronal plane. A custom handheld laryngeal stage was used to capture OCT images with 800 A-lines at 250 Hz. Automated image postprocessing and analytical methods were developed. Novel kinematic analysis of in vivo, long-range OCT imaging of the vibrating VF in awake human subjects is reported. Cross-sectional, coronal-plane panoramic videos of the larynx during phonation are presented with three-dimensional videokymographic and space-time velocity analysis of VF motion. Long-range OCT with automated computational methods allows for cross-sectional dynamic laryngeal imaging and has the potential to broaden our understanding of human VF biomechanics and sound production.
| S-EPMC8374544 | biostudies-literature
Project description:In this prospective study, we analysed the changes in retinal vessel density (VD) using optical coherence tomography angiography (OCTA) in patients with commotio retinae up to 6 months after blunt ocular trauma. We analysed the VD in the superficial capillary plexus (SCP), deep capillary plexus (DCP), radial peripapillary capillary (RPC) and the foveal avascular zone (FAZ) area at 48 h, and 1, 3 and 6 months after the trauma and compared results with those of healthy fellow eyes. We also evaluated the best-corrected visual acuity (BCVA) and the structural, spectral domain (SD)-OCT parameters: ganglion cell complex (GCC) and retinal nerve fibre layer (RNFL). A total of 18 eyes of 18 patients (8 males, 10 females, mean age 49.61 ± 9.2 years) and 18 healthy control eyes were evaluated. GCC and RNFL thicknesses showed a significant trend towards progressively lower values from 1 month and 3 months after the trauma, respectively, compared to healthy eyes (p < 0.005). The reduction in SD-OCT parameters reached a plateau at 6 months. Similar behaviour was found in the VD of the SCP and RPC that significantly decreased, starting from 1 and 3 months after the trauma, respectively (p < 0.001). At 6 months, the VD values were stable. The DCP presented an initial decrease of VD (p < 0.001), and after 1 month, the values statistically increased until the sixth month, reaching values similar to those of the control group. The FAZ area and BCVA did not show statistically significant changes during the follow-up. OCTA provided a detailed and quantitative analysis of early retinal vascular perfusion alterations after commotio retinae, demonstrating that the impairment of the retinal microvasculature and its progressive changes over time occurred even in the absence of compromised visual acuity.
| S-EPMC7602990 | biostudies-literature
Project description:PurposeTo compare quantitative optical coherence tomography angiography (OCT-A) measurements of the parafoveal microvasculature in retinal capillary plexuses among Behҫet uveitis (BU) patients, non-ocular Behҫet's disease (NOBD) patients, and healthy volunteers (HVs).MethodsSixty-eight subjects were enrolled in this prospective observational cross-sectional study. OCT-A imaging was performed using the Heidelberg Engineering Spectralis OCT. A custom algorithm was developed to calculate the vessel density (VD) in three retinal vascular layers: deep capillary plexus, intermediate capillary plexus, and superficial vascular plexus. The foveal avascular zone (FAZ) and acircularity index were calculated for the whole retinal vascular complex.ResultsWe analyzed one eye from 21 BU patients (age, 51 ± 10 years), 23 NOBD patients (age, 48 ± 14 years), and 22 HVs (age, 44 ± 13 years). One-way multivariate analysis of covariance showed a statistically significant difference in VD among the three groups when combining the layers after controlling for scan quality (P < 0.001). The VD was lowest in the BU group and highest in the HV group in all layers. The FAZ area was also statistically significant different among the groups (P < 0.005), with the largest FAZ areas in BU patients and smallest FAZ areas in the HV group. However, no statistically significant difference was found for the acircularity index.ConclusionsThe parafoveal microvasculature is affected not only in BU patients but also in NOBD patients. Most deviations in the retinal microcirculation in Behҫet patients were found in the deeper layers of the retina by using the quantitative VD measurement.
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Project description:Optical coherence tomography (OCT) is a rapidly evolving technology with a broad range of applications, including biomedical imaging and diagnosis. Conventional intensity-based OCT provides depth-resolved imaging with a typical resolution and sensitivity to structural alterations of about 5-10 microns. It would be desirable for functional biological imaging to detect smaller features in tissues due to the nature of pathological processes. In this article, we perform the analysis of the spatial frequency content of the OCT signal based on scattering theory. We demonstrate that the OCT signal, even at limited spectral bandwidth, contains information about high spatial frequencies present in the object which relates to the small, sub-wavelength size structures. Experimental single frame imaging of phantoms with well-known sub-micron internal structures confirms the theory. Examples of visualization of the nanoscale structural changes within mesenchymal stem cells (MSC), which are invisible using conventional OCT, are also shown. Presented results provide a theoretical and experimental basis for the extraction of high spatial frequency information to substantially improve the sensitivity of OCT to structural alterations at clinically relevant depths.
| S-EPMC8385072 | biostudies-literature
Project description:With a Gaussian-like broadband light source from high brightness Ce(3+):YAG single-clad crystal fiber, a full-field optical coherence tomography using a home-designed Mirau objective realized high quality images of in vivo and excised skin tissues. With a 40 × silicone-oil-immersion Mirau objective, the achieved spatial resolutions in axial and lateral directions were 0.9 and 0.51 μm, respectively. Such a high spatial resolution enables the separation of lamellar structure of the full epidermis in both the cross-sectional and en face planes. The number of layers of stratum corneum and its thickness were quantitatively measured. This label free and non-invasive optical probe could be useful for evaluating the water barrier of skin tissue in clinics. As a preliminary in vivo experiment, the blood vessel in dermis was also observed, and the flowing of the red blood cells and location of the melanocyte were traced.
| S-EPMC4230872 | biostudies-other