Ultrahigh resolution functional optical coherence tomography

Research project P 14218 Ultrahigh resolution functional optical coherence tomography Oliver FINDL 08.05.2000 In the last decade, a novel non-invasive optical biomedical imaging technology, called optical coherence tomography (OCT) has been developed. OCT is an emerging technology for ophthalmic diagnosis which can perform noncontact, noninvasive, real time, cross-sectional imaging of the retina and anterior eye. It is analogous to conventional ultrasonic pulse-echo imaging, except that OCT uses infrared light rather than acoustic waves. Standard ophthalmic OCT has 10 m m axial resolution, 10 times higher than conventional ultrasound. Recently, using state of the art laser technologies, OCT imaging with ultrahigh resolutions. of I m m has been demonstrated. In addition, OCT imaging can be extended to perform not only morphological measurements, but also functional imaging such as spectroscopic measurements of functional signatures such as oxygenation. The proposed program is a multidisciplinary collaborative research project involving investigators at the University of Vienna, the General Hospital of Vienna, the University of Karlsruhe and the Massachusetts Institute of Technology in Cambridge. The objective is to develop new OCT technology which achieves a quantum leap in performance over current ophthalmic OCT and to demonstrate this technology for the early diagnosis and monitoring of retinal diseases. We will increase OCT axial image resolutions by 5-10 times, from 10 m m to ~1-2 m m and also develop multiwavelength, spectroscopic, functional OCT techniques to improve differentiation of morphology and permit micron scale functional imaging. Our hypothesis is that these advances will dramatically enhance the ability to image structural morphology such as intraretinal features, as well as improve the accuracy and reproducibility of morphometric measurements such as retinal thickness and nerve fiber layer thickness. Our hypothesis is that these structures are resolved by ultrahigh resolution OCT and are relevant for the diagnosis and monitoring of early posterior segment disease. We will specifically investigate applications in three leading causes of blindness, age-related macular degeneration, glaucoma, and diabetic retinopathy. Although no curative therapy exists, there are several medical and surgical therapies that may significantly delay serious visual impairment. Our objective is to develop ultrahigh resolution and functional OCT to provide clinically relevant data to diagnose disease at a point when to provide clinically relevant data to diagnose disease at a point when treatment is most effective and to accurately track disease progression.

A non-invasive, ophthalmic diagnostic technique has been developed that achieves a quantum leap in pe-formance in early diagnosis of retinal pathologies, that are worldwide leading causes of blindness. This has been accomplished in the framework of a multidisciplinary collaborative research project involving investigators at the Department of Medical Physics, University of Vienna, the Department of Ophthalmology, General Hospital of Vi- enna, the Department of Electrical Engineering and Computer Science of the Massachusetts Institute of Technology, Cambridge, and Femtolasers Produktions GmbH, Vienna, Austria. By significantly improving the resolution performance of a non-contact optical imaging technique, known as optical coherence tomography (OCT), visualization of the living human retina with a performance similar to that possible with standard histology of excised retinas, has been achieved. OCT is an emerging non-invasive, optical medical diagnostic imaging modality, which enables in vivo cross- sectional tomographic visualization of internal microstructure in biological systems, achieving unprecedented image resolutions. By employing a state of the art broad bandwidth laser source in connection with a specifically developed optical setup, detection electronics, software as well as hardware, a laboratory prototype of this new generation of ophthalmic OCT system has been developed and successfully tested in a clinical study in more than 300 eyes of patients with different retinal pathologies. Preliminary results achieved within the framework of this grant, demonstrating the potential of this technique to also extract spatially resolved spectroscopic (i.e. biochemical) as well as functional (e.g. blood flow) information of the retina in addition to unprecedented visualization of intraretinal morphology will be future research directions as well as further developments of this technique for high speed, three dimensional, ultrahigh resolution visualization of intraretinal layers. It is unlikely that this novel version of OCT will replace other existing diagnostic modalities in ophthalmology. However, from the viewpoint of screening and diagnosis of diseases, the newly developed version of OCT might enable significantly new insight in the pathogenesis and the development as well as monitoring of therapy control of several diseases. In addition, it might dramatically enhance early detection in a variety of ocular pathologies that are worldwide leading causes of blindness.