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Mirjam E J van Velthoven

Publications and source records attributed to Mirjam E J van Velthoven.

5 recordsLinked to original sources
PubMed2006

Recent developments in optical coherence tomography for imaging the retina.

Optical coherence tomography (OCT) was introduced in ophthalmology a decade ago. Within a few years in vivo imaging of the healthy retina and optic nerve head and of retinal diseases was a fact. In particular the ease with which these images can be acquired considerably changed the diagnostic strategy used by ophthalmologists. The OCT technique currently available in clinical practice is referred to as time-domain OCT, because the depth information of the retina is acquired as a sequence of samples, over time. This can be done either in longitudinal cross-sections perpendicular to, or in the coronal plane parallel to the retinal surface. Only recently, major advances have been made as to image resolution with the introduction of ultrahigh resolution OCT and in imaging speed, signal-to-noise ratio and sensitivity with the introduction of spectral-domain OCT. Functional OCT is the next frontier in OCT imaging. For example, polarization-sensitive OCT uses the birefringent characteristics of the retinal nerve fibre layer to better assess its thickness. Blood flow information from retinal vessels as well as the oxygenation state of retinal tissue can be extracted from the OCT signal. Very promising are the developments in contrast-enhanced molecular optical imaging, for example with the use of scattering tuneable nanoparticles targeted at specific tissue or cell structures. This review will provide an overview of these most recent developments in the field of OCT imaging focussing on applications for the retina.

Humans↗
PubMed2006

Combined en-face optical coherence tomography and confocal ophthalmoscopy findings in active multifocal and serpiginous chorioretinitis.

PURPOSE: To describe retinal changes in active multifocal and serpiginous chorioretinitis seen with en-face optical coherence tomography (OCT). DESIGN: Observational case report. METHODS: Two patients, presenting with active multifocal chorioretinitis (MFC) and serpiginous chorioretinitis (SC), respectively, were scanned with a prototype en face OCT ophthalmoscope. RESULTS: The OCT scan in the patient with the active MFC lesion showed a transretinal hyperreflectivity at the site of lesion. The OCT scan in the patient with the active SC lesion showed hyper-reflectivity in the outer retina at the site of the lesion. CONCLUSIONS: OCT allows for better evaluation of intraretinal changes in patients with white dot syndromes. In these two cases, OCT showed different morphologic changes in active lesions. OCT may be helpful in identifying the location of involvement in various white dot syndromes. This may have prognostic and therapeutic significance.

Adult↗
PubMed2006

Imaging the retina by en face optical coherence tomography.

PURPOSE: To present the possibilities of a new system that combines optical coherence tomography (OCT) and confocal ophthalmoscopy, producing en face OCT images in patients with retinal diseases. METHODS: A prototype OCT Ophthalmoscope (OTI, Toronto, Canada) was used to scan patients with retinal conditions. The system uses a super luminescent diode (lambda = 820 nm; Deltalambda = 20 nm) and currently scans at a rate of 2 frames per second. In each frame, the OCT Ophthalmoscope simultaneously produces a transversal OCT scan and a confocal image in the X/Y plane. Both images correspond pixel to pixel. RESULTS: Between January 2002 and August 2003, >800 patients with various retinal diseases were scanned with the OCT Ophthalmoscope. Illustrative cases with regularly seen macular diseases are presented, such as macular hole and central serous retinopathy. CONCLUSION: Current difficulties as well as future possibilities of this new en face OCT ophthalmoscope are discussed. By presenting normal and pathologic transversal OCT images made by a prototype OCT Ophthalmoscope, we show that it can provide information not available using conventional OCT imaging.

Humans↗
PubMed2005

Overlay of conventional angiographic and en-face OCT images enhances their interpretation.

BACKGROUND: Combining characteristic morphological and functional information in one image increases pathophysiologic understanding as well as diagnostic accuracy in most clinical settings. En-face optical coherence tomography (OCT) provides a high resolution, transversal OCT image of the macular area combined with a confocal image of the same area (OCT C-scans). Creating an overlay image of a conventional angiographic image onto an OCT image, using the confocal part to facilitate transformation, combines structural and functional information of the retinal area of interest. This paper describes the construction of such overlay images and their aid in improving the interpretation of OCT C-scans. METHODS: In various patients, en-face OCT C-scans (made with a prototype OCT-Ophthalmoscope (OTI, Canada) in use at the Department of Ophthalmology (Academic Medical Centre, Amsterdam, The Netherlands)) and conventional fluorescein angiography (FA) were performed. ImagePro, with a custom made plug-in, was used to make an overlay-image. The confocal part of the OCT C-scan was used to spatially transform the FA image onto the OCT C-scan, using the vascular arcades as a reference. To facilitate visualization the transformed angiographic image and the OCT C-scan were combined in an RGB image. RESULTS: The confocal part of the OCT C-scan could easily be fused with angiographic images. Overlay showed a direct correspondence between retinal thickening and FA leakage in Birdshot retinochoroiditis, localized the subretinal neovascular membrane and correlated anatomic and vascular leakage features in myopia, and showed the extent of retinal and pigment epithelial detachment in retinal angiomatous proliferation as FA leakage was subject to blocked fluorescence. The overlay mode provided additional insight not readily available in either mode alone. CONCLUSION: Combining conventional angiographic images and en-face OCT C-scans assists in the interpretation of both imaging modalities. By combining the physiopathological information in the angiograms with the structural information in the OCT scan, zones of leakage can be correlated to structural changes in the retina or pigment epithelium. This strategy could be used in the evaluation and monitoring of patients with complex central macular pathology.

Choroid Diseases↗