Abstract

FR.23.03

Light in vitreoretinal surgery

Stefan Dithmar1, Alexandra Hoeh1, Roman Amberger2, Mira Ruppenstein1, Thomas Ach1
1Universitäts-Augenklinik Heidelberg; 2Kirchhoff-Institut für Physik, Heidelberg

Objective
The new generation of light sources for vitreoretinal surgery allows excellent intraoperative visualization. However, the risk of induced light toxicity is often not exactly known by surgeons. The aim of this study is to summarize relevant factors for photochemical light damage and to examine commercially available light sources and endoilluminators regarding these factors.
Methods
We examined six different light sources (Accurus, Xenotron II, Megatron S3, Bright Star, Photon 1 und Photon 2) and associated light fibers (20ga, 23ga, focused and wide-field endoilluminators). Wavelength spectra and radiant power were measured. Maximal irradiances for different working distances to the retina were determined. Maximally tolerable operating times were calculated.
Results
Wavelenght spectra differ significantly among the examined light sources, even within the blue light zone. Additive filters eliminate short wavelenghts effectively, but can also reduce the intraoperative visualization of retinal details. There are considerable differences in maximal irradiances between light sources (up to factor 30). Calculated maximally tolerable operating times for 5 mm working distance vary from 0,7 minutes to 4 hours.
Conclusions
Commercially available light sources for vitreoretinal surgery offer excellent intraoperative visualization. However, the physical characteristics of the devices differ substantially. In order to avoid retinal light damage the user should have detailed knowledge about the properties of his light source and endoilluminators. Wavelenght spectrum, irradiance, type of endoilluminator, working distance and operating time are important factors for the risc of light toxicity.

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