A telemedical approach to the screening of diabetic retinopathy: digital fundus photography.

OBJECTIVE: The importance of screening for diabetic retinopathy has been established, but the best method for screening has not yet been determined. We report on a trial of assessment of digital photographs by telemedicine compared with standard retinal photographs of the same fields and clinical examination by ophthalmologists. RESEARCH DESIGN AND METHODS: A total of 129 diabetic inpatients were screened for diabetic retinopathy by slit-lamp biomicroscopy performed by an ophthalmologist and by two-field 50 degrees non-stereo digital fundus photographs assessed by six screening centers that received the images by electronic mail. Conventional 35-mm transparencies of the same fields as the digital photographs were assessed by a retinal specialist and served as the reference method for detection of diabetic retinopathy. Slit-lamp biomicroscopy was the reference method for the detection of macular edema. RESULTS: The prevalence of any form of diabetic retinopathy was 30% (n = 35); of sight-threatening retinopathy including macular edema, the prevalence was 6% (n = 7). The assessment of digital images by the six screening centers resulted in a median sensitivity of 85% and a median specificity of 90% for the detection of moderate nonproliferative or sight-threatening diabetic retinopathy. Clinically significant macular edema (n = 4) was correctly identified in 15 of the 24 grading reports. An additional seven reports referred the patients for further investigation because of concurrent diabetic retinopathy. CONCLUSIONS: Telescreening for diabetic retinopathy by an assessment of two-field 50 degrees non-stereo digital images is a valid screening method. Although detection of clinically significant macular edema using biomicroscopy is superior to digital or standard non-stereo photographs, only few patients with sight-threatening diabetic retinopathy are missed.

[Scientific role of German ophthalmology in the European telecommunication project OPHTEL]. / Wissenschaftliche Rolle der deutschen Ophthalmologie im europäischen Telekommunikationsprojekt OPHTEL.

BACKGROUND: In Denmark, France, Germany, Great Britain and Italy, the OPHTEL project combines clinical centers of ophthalmology and internal medicine, an institute for medical informatics and health services research, a publishing company and different industrial partners in the EDP market. AIMS: With the aid of visual telecommunication and rapid data transfer, methods and conditions will be developed and proved so that any physician can very easily obtain sufficient information for treating his patient. Thus, the regional differences in the quality of structured health service (e.g., urban/ rural) will be overcome throughout Europe. SCIENTIFIC TASKS: A multilingual diagnostic and therapeutic thesaurus has to be worked out in order to create standards for communication and quality control. Based on literature, images and image analysis in a knowledge-based data bank, a monitoring system (containing watch-dog functions) and the basic aspects of an ophthalmological patient/disease register will be investigated. (In parallel, a technical development of synchronous and asynchronous telecommunication between eye physicians is taking place in close cooperation with the regional Bavarian project Teleopathalmology in Bavaria on-line). RESULTS: State of the art 6 months after starting the project:the knowledge-based image data bank has been founded and also an ophthalmological 8 language thesaurus and definition standard. All data transfer lines are installed. DISCUSSION: The project is taking place amid diverging sections of medicine: ophthalmology and internal medicine, health politics and data protection, individual treatment and common interest (health care), product management and office organization. Thus, the scientific quality of the transferred ophthalmological content must undergo sophisticated controls. FUTURE STEPS: Intense cooperation with the big German associations for ophthalmology (DOG, BVA) and the European ophthalmological societies concerning EDP, classification and quality control.

Diffusion properties of dye molecules in nanoporous TiO2 networks.

The adsorption of ruthenium-dye molecules out of ethanol solution onto TiO2 particles of nanoporous TiO2 films was used to study the molecules' diffusion through these layers by means of optical absorption spectrometry. Dependent on pore size, porosity, and particle size, effective diffusion constants as low as D(eff) = 4 x 10(-9) cm2/s were deduced from the uptake curves by applying a simple model for combined diffusion and adsorption. These diffusion constants for diffusion through the nanoporous network are up to 3 orders of magnitude lower than in bulk ethanol and are discussed with respect to the properties of the nanoporous material.

Displacement correction and surface reconstruction of the retina using scanning laser ophthalmoscopic images.

A method for a three-dimensional surface reconstruction of the retina in the area of the papilla is presented. The surface reconstruction is based on a sequence of discrete gray-level images of the retina recorded by a scanning laser ophthalmoscope (SLO). The underlying assumption of the surface reconstruction algorithm developed here is that the depth information is also encoded in the brightness values of the single pixels in addition to the ordinary spatial 2D information. The brightness of an image position depends on the degree of reflection of a confocal laser beam. Only those surface structures located directly in the focus plane of the confocal laser beam produce a high response to the laser light. The displacements between the single images of a sequence are considered to be approximately linear and are corrected by applying the cepstrum technique. The depth is estimated from the volumetric representation of the image sequence by searching for the maximal value of the brightness within a computed depth profile, at every image position. In the resulting images, disturbances occurring during the recording cause incorrect local estimations of the depth. These local disturbances are corrected by applying specially developed surface improvement processes. The work is concluded with a comparison of several different approaches to reduce the noise and disturbances in SLO image data.

[Teleconsultation network for ophthalmology--experiences and results]. / Telekonsultationsnetzwerk für die Ophthalmologie--Erfahrungen und Ergebnisse.

MOTIVATION: Telemedical services for ophthalmology are developed within the OPHTEL project, which has been funded by the European Union and by the Bavarian government in the Bavaria-online initiative. METHODS: Seven private ophthalmologists, one university eye clinic, one clinical Diabetes center and an informatics research institute are connected within a teleconsultation network. Asynchronous (based on Internet E-Mail) and synchronous (based on ISDN-mediated videoconferencing tools) types of teleconsultations are realized. RESULTS: 86 teleconsultations (62 asynchronous, 23 synchronous) took place within the first 10 months. Complex and rare eye diseases as well as interdisciplinary questions (ophthalmology--diabetology) are the main area of medical communication interest. Legal and security problems are discussed. CONCLUSIONS: Telemedical services must be understood as a complete process of medical care on the basis of modern communication technologies, which influences also the management of this process.