Automated illumination control for use in ophthalmic endoscopy

摘要

Abstract: In endoscopic ophthalmic procedures care has to be exercised that the retina is protected from overexposure. Accordingly, it is advantageous if the endoscope is equipped with a stable and reliable automatic illumination control. To this end, an illumination control system has been devised, which consists of a mechanical iris and a digital control algorithm. The iris is designed such that it influences neither the spectral composition of the lightsource nor its aperture. It is furthermore linear with respect to the light intensity such that a fast control algorithm based on the data of a digital video camera used for observation purposes can be implemented. In order that no false signals are induced from specular reflections caused, e.g., by operating tools held in front of the camera, the control algorithm is designed such that reflections and true overexposure are distinguished from each other. For this purpose, the field of view is subdivided into small sectors and a statistical evaluation is made. The application under realistic conditions shows that the unit provides the user with a well illuminated image while the retina is reliably protected from overexposure. !14