Christian Enders

Neue Möglichkeiten in der retinalen Diagnostik mittels OCT-Angiografie

BACKGROUND Instruments for using OCT angiography (OCTA) in daily clinical practice have recently become available. The aim of this paper is to report the possibilities, advantages and limitations of OCTA in the clinical diagnosis of diseases of the posterior segment of the eye. PATIENTS/METHODS Patients with diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration who had been assigned to fluorescein angiography (FA) additionally underwent an AngioPlex™-OCTA examination, which captures a 6 × 6 mm scanning area centred on the fovea. If deemed necessary, 3 × 3 mm volume scans were created in regions of interest. The findings of FA and OCTA were correlated and compared. RESULTS The OCTA procedure took only a few seconds, was easily integrated into the standard OCT diagnostic imaging procedure, and delivered highly detailed, three dimensional images of the entire microvasculature of the retina and choroid. Microvascular changes, such as microaneurysms, intraretinal microvascular abnormalities, non-perfused areas, alterations in the foveal avascular zone (FAZ) and neovascularization were reliably detected. Overall, OCTA results were in good agreement with the results of the FA. Additionally, OCTA provided more detailed and three dimensional information and thus permitted a better assessment of the spatial extension of microvascular abnormalities. Due to OCTAs limited scanning area, vascular alterations in the mid-periphery were detected only if their location had already been determined by FA. Although OCTA does not show leakage, macular oedema can be diagnosed from OCTA, together with OCT thickness measurements. CONCLUSION OCTA provides important three dimensional information on vascular alterations and is already an indispensable diagnostic method. As the procedure takes just a few seconds and can be performed non-invasively, OCTA is well suited as a monitoring method and may allow early diagnosis. In this sense, prospective studies are required to determine precise OCTA analytical strategies for specific diseases. It is very likely that OCTA will revolutionise the diagnosis of retinal and choroidal diseases; however, it is not yet clear estimated to what extent it will replace FA.

Präzise Befundung mit der OCT-Angiografie – Artefakte erkennen und ausschließen

Background Optical coherence tomography angiography (OCTA) provides, non-invasively, a three-dimensional visualization of the microvasculature of the retina and choroid. However, image artifacts may occur in OCTA and have an impact on clinical interpretation. The aim of this article is to describe image artifacts of OCTA and to present a nomenclature. Methods OCTA examinations were performed with the AngioPlex™ OCTA-technology in combination with the CIRRUS HD-OCT 5000 (Carl Zeiss Meditec, Inc., Dublin, USA) as well as with the PlexElite 9000 (Carl Zeiss Meditec, Inc., Dublin, USA). Typical artifacts identified in the OCTA images are described and their causes are explained. Results There are three main groups of artifacts that can be distinguished: (a) artifacts that are inherent in the OCTA technology and occur with all types of devices (projection artifacts, masking, unmasking, loss of signal); (b) artifacts caused by data and image processing algorithms and whose frequency or severity may depend on the device type used (segmentation artifacts, duplications of vessels); (c) motion artifacts that vary in frequency and severity depending on the type of device used, as different methods (e.g., eye tracker) are used to reduce them. The occurrence of artifacts is also dependent on patient cooperation, the clarity of the optical media, and the pathology of the retina. Conclusion As in any other imaging method, artifacts also occur in OCTA images. Nevertheless, qualitative assessment of OCTA images is almost always possible and provides indispensable findings on the morphology and perfusion status of the retina and choroid. A good knowledge of possible artifacts, and a critical analysis of the complete OCTA data set, allows a correct interpretation and is essential for making a precise clinical diagnosis.

Multi-Modal Imaging Including Optical Coherence Tomography Angiography in Patients With Posterior Multifocal Placoid Pigment Epitheliopathy

BACKGROUND AND OBJECTIVE New imaging methods provide novel insights into the pathogenesis of acute posterior multifocal placoid pigment epitheliopathy (APMPPE). PATIENTS AND METHODS Four patients (eight eyes) in acute, subacute, and late phases of the disease were analyzed with multi-modal imaging methods including optical coherence tomography angiography (OCTA), structural OCT, fundus photography, and fundus autofluorescence. One patient was observed during the entire disease course. RESULTS In acute and subacute phases of the disease, an early blockage in fluorescein angiography was found. OCTA showed perfusion defects in choriocapillaris and choroid slabs. During the course of disease, perfusion deficits observed in OCTA imaging resolved first in the choroid and then in the choriocapillaris slab. CONCLUSION Multi-modal imaging including OCTA supports the thesis that the underlying pathology of APMPPE is an inflammatory impairment of the choroidal circulation with secondary damage to the outer retina. OCTA might be able to replace fluorescein and indocyanine angiography in the diagnostic work-up of APMPPE. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:727-733.].

Advanced Non-Destructive Ocular Visualization Methods by Improved X-Ray Imaging Techniques

Due to limited X-ray contrast, the use of micro-CT in histology is so far not as widespread as predicted. While specific staining procedures—mostly using iodine—address this shortcoming, long diffusion times restrict its use in the often time-constrained daily routine. Recently, a novel staining protocol has been proposed using a biochemical preconditioning step, which increases the permeability of the cells for the staining agent. This could enable the imaging of entire organs of small mammals at a yet unmatched image quality with reasonable preparation and scan times. We here propose an adaptation of this technique for virtual ophthalmology and histology by volumetrically assessing both human and porcine eyes. Hereby, we demonstrate that (contrast-enhanced) micro-CT can outperform conventional histology in the assessment of tumor entities, as well as functioning as a supplementary tool for surgeons in the positioning of intraocular implants in-vitro and as a general assessment tool for ophthalmologic specimens.

Zertifizierung des Qualitätsmanagements nach DIN EN ISO 9001:2015

Quality management improves the structures, processes and results of organizations of all kinds. Many practices and clinics have their existing quality management system certified according to ISO 9001, (e.g., to check their own quality management system or to obtain a testimonial against third parties). The latest version ISO 9001:2015 contains some changes, both structurally and in terms of content. These changes can be met with reasonable efforts. An ISO 9001:2015 certification represents a value for your organization, but these advantages are often not directly measurable.

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

Purpose: Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. Methods: The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). Results: A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). Conclusion: The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.