BAcKground: Diaphanoscopy is an old but still useful technique in ophthalmic diagnostics. Its application suffers somewhat from the fact that the light is strongly attenuated and red-shifted in color when the eye wall is transilluminated. MAterIAL And MetHodS: A color adjustable diaphanoscope prototype is developed based on a powerful red-green--blue-white light-emitting diode (RGBW-LED). Its optical and thermal properties are measured and tested on the porcine eyes of a local butcher. In addition, based on the technical data, the assumed retinal hazard to human eyes is assessed according to the standard DIN EN ISO 15004-2: 2007-6. reSuLtS: The investigated porcine eyes were brightly illuminated with all LED colors. The calculated values for judging the thermal and photochemical hazard were below the limits given in DIN EN ISO 15004-2: 2007-6. concLuSIon: Based on the standard mentioned above, there is no recognizable danger to the human retina when applied for a limited time, and at least in the porcine model, the presented RGBW-LED diaphanoscope allows an adjustable ophthalmological transillumination without the requirement of the more elaborated devices that are usually employed in operating rooms.
For the visualisation of the intraocular space it is essential to illuminate the inside of the eye. One illumination approach is diaphanoscopy, in which the light of an extraocular source is transmitted through the tissue layers of the eyewall. The transmission properties of these tissues and their irradiation load depend on applied diaphanoscope contact pressure. However, excessive illumination can lead to irreversible photochemical and thermal damage to the retina. In diaphanoscopic illumination, the retina is particularly at risk due to its proximity to the light source. Therefore, the photochemical and thermal retinal hazards, resulting from direct transmitted light through the eyewall, are determined for different applied pressures of the diaphanoscope on the eye (15, 65 and 115 kPa). The study is performed on porcine eyes with different pigmentation. So, the difference in intraocular irradiance, photochemical and thermal hazards, as well as the maximal exposure time is also examined for different pigmentations. For less pigmented eyes the irradiance inside the eye, the photochemical and the thermal hazard are higher than for higher pigmented eyes. The values also become significantly higher for increasing applied pressure with the diaphanoscope but do not exceed given limits in the standard DIN EN ISO 15004-2: 2014.
Background: In current vitrectomy, the surgeon guides the vitrectome and a rigid fiber light guide with one hand each. It would be desirable to have a free hand for other surgical instruments and maneuvers. Methods: In the feasibility study presented here, a 20 gauge vitrectome is equipped with a miniature white LED that could eliminate the need for the separate light guide and therefore free one hand. The functionality of the system is proved in a ping-pong ball filled with agar and an ex-vivo porcine eye. Results: The brightness of the approach appears to be sufficient without any realistic phototoxic retinal hazard while the functionality of the vitrectome, in combination with the LED, is still given. Conclusion: The combination of a 20 gauge vitrectome with a LED illumination unit was successfully tested. The approach can be transferred to small vitrectomes in the future
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