Abstract

P 237

Recent advances in the development of an artificial accommodation system

Jörg Nagel1, Ulrich Gengenbach1, Helmut Guth1, Thomas Martin1, Liane Rheinschmitt1, Georg Bretthauer1, Rudolf Guthoff2
1Institut für Angewandte Informatik, Forschungszentrum Karlsruhe, Eggenstein-Leopoldshafen; 2Universitäts-Augenklinik Rostock

Objective
In an aging society, presbyopia and cataract are gaining importance. The decrease of accommodative ability can be compensated by means of visual aids. In the case of cataract the cloudy lens usually is being replaced by a rigid IOL. There are many activities worldwide to restore accommodation. A new approach which is being pursued here is an Artificial Accommodation System; an intelligent micro system that is intended to be implanted into the capsular bag in place of an intraocular lens. This system shall autonomously adapt the refractive power of an integrated active optical element to the accommodation demand.
Methods
In order to develop such a micro system its requirements both from the opthalmological and technical point of view were identified and the following sub-functions derived: Measurement of accommodation demand, change of refraction power, system control, communication and energy supply. All components must fit into the limited space of the capsular bag. The system must be biocompatible, implantable with state of the art ophthalmological surgical methods and operate reliably for a long life cycle.
Results
This paper outlines the basic investigations, which lead to implementations of the above defined sub-functions. For measurement of accommodation demand both approaches relying on body reactions e.g. pupil near reaction and direct distance measurement or observation of the sighted object have been evaluated. Lens systems with axial and lateral shift as well as lenses which directly alter the shape of the refracting surfaces were assessed as candidate elements with variable refraction power. For the mechanically moved optical elements actuators and linkages were researched respectively. Moreover novel energy storage concepts, inductive energy transmission and energy harvesting were evaluated for energy supply of the overall system. The complex lifetime and biocompatibility requirements are challenges that entail intensive efforts with respect to systems integration.
Conclusions
A selection of subsystems together with processes to integrate them into an implantable micro system will be available at the end of the basic investigation phase. This will be the grounds to eventually provide a solution to really restore accommodation.

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