[OCT in macular diagnostics - possibilities and limitations]. / OCT in der Makuladiagnostik - Möglichkeiten und Grenzen.

During the last years, optical coherence tomography (OCT) has evolved to an important diagnostic tool in ophthalmology. In addition to ophthalmoscopy and the topographic visualisation of pathologies of the posterior part of the eye by fluorescein and indocyanine-green angiography, OCT adds complementary tomographic information on the retinal structures. First generation (time domain) OCT machines already generated pictures that resemble histological cross-sections of the retina. With the new OCTs of the spectral/frequency/Fourier domain generation, topographic and tomographic information can be presented side-by-side or in combination, thereby increasing the accuracy of the localisation of the visualised structures. Because of its non-invasive methodology without contact to the patient's eye and the faster acquisition times with increasing resolution, the OCT has become a valuable instrument in the modern anatomic and structural diagnostics of the macula. Functional statements are not yet possible in a comprehensive manner, but first steps have been made with the interpretation of structural information from high-resolution images. In this paper, the emerging possibilities from a widespread use of the OCT, as well as the limitations of this diagnostic technique, are discussed.

[Evidence-based diagnostic approach to inherited retinal dystrophies 2009]. / Evidenzbasierte Diagnostik hereditärer Netzhautdystrophien 2009.

BACKGROUND: Hereditary retinal dystrophies comprise a heterogeneous group of inherited retinal disorders with variable clinical presentation and multiple associated genes. Clinical diagnosis and differential diagnosis are difficult. The purpose of the current paper is to provide guidelines for an effective diagnostic approach. METHODS: A literature search was carried out and our own data on clinical (n = 3200) and molecular genetic (n = 4050) diagnosis of patients with retinal dystrophies were evaluated. RESULTS: For an early diagnosis it is of importance to include inherited retinal dystrophies in the differential diagnosis of unexplained visual disturbances. The most important clinical test is the full-field electroretinogram (ERG), which allows detection or exclusion of generalised retinal dystrophies. If the full-field ERG is normal, a multifocal ERG will distinguish macular dystrophies. Fundus autofluorescence, near-infrared autofluorescence and high resolution optical coherence tomography improve the early diagnosis because morphological alterations can be detected prior to their ophthalmoscopic visibility. In addition, these non-invasive imaging techniques reveal new phenomena which are important for the differential diagnosis and follow-up of retinal dystrophies as well as for an improved understanding of their pathogenesis. Routine molecular genetic diagnosis is available for an increasing number of retinal dystrophies. A succinct clinical diagnosis is a prerequisite to allow selection of the gene(s) to be analysed. If genetic testing is indicated, a human geneticist should be involved for counselling of the patient and possibly further family members and initiation of the necessary steps for DNA testing. CONCLUSION: The combination of electrophysiological testing, retinal imaging and molecular genetic analysis allows a differentiated diagnosis of inherited retinal dystrophies and an individual counselling of patients. If inherited retinal dystrophies are suspected, a detailed examination in a retinal centre specialised on inherited retinal dystrophies is recommended.

[Optical coherence tomography: from retina imaging to intraoperative use - a review]. / Ubersicht der apparativen Entwicklungen in der optischen Kohärenztomografie: von der Darstellung der Retina zur Unterstützung therapeutischer Eingriffe.

BACKGROUND: Optical coherence tomography (OCT) is new diagnostic procedure that has rapidly evolved in the last years. The recently developed spectral domain OCT allows one to increase the imaging speed by a hundred times compared to the first generation time domain OCT and enables three-dimensional imaging as well as real-time imaging of fast moving structures. Volumetric imaging improves the quantitative measurement of morphology and the evaluation of temporal changes. In addition, an exact correlation with images acquired with other imaging modalities is possible. Real-time imaging enables also the use of OCT during examinations with the slit-lamp and during ophthalmological surgery. METHODS: A spectral domain OCT was adapted to a slit lamp. 70 patients (91 eyes) were examined at the anterior or posterior segment of the eye. Images of healthy structures and different pathologies were compared to OCT images obtained with Stratus 3, Spectralis, and the SL-OCT. To demonstrate the feasibility of OCT during surgery, spectral domain OCT devices working with 20,000 and 210,000 A scans per second were coupled by specially developed optics to the camera port of a surgical microscope. The device was tested with phantoms and enucleated pig eyes. RESULTS AND CONCLUSIONS: A 5 kHz spectral domain OCT can image the retina during slit lamp-based indirect ophthalmoscopy with a quality similar to that of the Stratus 3. In addition, relevant structures of the anterior segment were imaged. Here, compared to commercially available devices, the imaged field was smaller and the angle of the anterior chamber was not directly visible due to the 830 nm wavelength, which had to be used for retinal imaging. Through the surgical microscope, a volumetric imaging of epithelium, Bowman's, Descemet's membranes, limbus, iris, lens, conjunctiva and sclera was demonstrated with several tens of centimetre working distance. Instruments and incisions in the cornea were visualised with 20 microm precision. Real-time imaging and visualisation of volumetric OCT data were also demonstrated. In principle, all technical problems of an intraoperative use of OCT have been solved and a clinical trial will start in the near future. OCT has the potential to improve the precision of surgical interventions and may even enable new interventions.

[New options of high resolution optical coherence tomography in glaucoma diagnostic]. / Neue Möglichkeiten der hochauflösenden optischen Kohärenztomographie in der Glaukomdiagnostik.

At present time domain optical coherence tomography (TD-OCT) plays a less important role in glaucoma diagnostics and is used mainly for macula diagnostics. The Fourier domain optical coherence tomography (FD-OCT) with enhanced resolution has new options to detect glaucoma changes. This new technology is referred as frequency domain or spectral domain OCT. This paper will present current and new options of OCT in glaucoma diagnostics. Measurements of the optic nerve head and the retinal nerve fiber layer thickness using this new technology have been shown to be reproducible. Devices which use TD-OCT (e.g. Stratus-OCT) have a lower resolution than devices that use FD-OCT (e.g. RTVue-100; 10 microm versus 5 microm axial resolution). A new option is the evaluation of the retinal ganglion cell complex. The measurement of the optic nerve head and the retinal nerve fiber layer using FD-OCT are promising for glaucoma diagnostics. How this new technology, especially the ganglion cell complex analysis is comparable to other technologies and whether it is helpful for glaucoma diagnostics and monitoring of management will be evaluated in future studies.