The C-ETD consists of a head mounted unit and a system computer. The system computer comprises a state-of-the-art PC with two plug-in boards for processing of the image data from the right and the left eye. The digital eye tracking cameras - designed around state-of-the-art CMOS image sensors - are interfaced to a dedicated processor board in the host PC via bi-directional, high speed digital transmission links (up to 400 images/s). This plug-in board carries the front-end processing architecture, consisting of digital signal processors (DSP) and programmable logic devices (FPGA) for binocular, online image and signal acquisition. The head unit is individually adjustable for head size and interpupillary distance.

For the eye tracking task, a substantial data reduction is performed by the sensor and the front-end processing. Thus, only preselected data are transferred from the image sensor through to the host PC where the final algorithms and data storage are implemented. This eliminates the bottleneck caused by standard frame-by-frame image acquisition, and thus facilitates considerably higher image sampling rates. The design also permits storage of all online acquired image data for subsequent analysis and/or visual evaluation. The device provides the clinician and researcher with state-of-the-art quality in the comprehensive measurement of eye movement (horizontal, vertical, torsional & vergence components) with optional measurement of six degrees-of-freedom head movement.

Originally developed for deployment on the International Space Station (ISS), the Chronos Eye Tracker introduced a novel approach to image-based eye movement measurement technology. CHRONOS VISION has further refined its design for use in clinical research and diagnostic. Accordingly, the device is certified according to the CE and FDA regulations for medical devices. In addition to its integration in the Human Research Facility on board the ISS, it is now CE-certified for clinical use. In comparison to existent techniques, the present technology provides the following features:

The spaceflight-qualified version of the eye tracking device integrated in cooperation with the Munich company Kayser Threde GmbH under the auspices of the German Space Agency (Deutsche Luft- und Raumfahrt Agentur - DLR) .

For many in the field of eye movement and oculomotor research the scleral search coil techniques represent the
gold standard.

The magnetic field search coil technique introduced in 1975 by Robinson and optimized for measurements of human eye movement by Collewijn et al in 1985 has become the most commonly used method for quantitative studies of eye and head movements in man and in experimental animals. The technique is based on phase-locked amplitude detection of the voltage induced in a search coil in the external ac magnetic field. For eye movement measurement in humans the search coil is embedded in a silicon ring, moulded so that it adheres to the sclera of the eye by suction.

While this technique is semi-invasive it has proved reliable for the precise measurement, particularly of three-dimensional eye movements and in cases where extreme eye movements are required for experimental purposes, or caused by oculomotor pathology.

As official successor to the original manufacturer of search coils, SKALAR Medical of Delft (NL), CHRONOS VISION manufactures and distributes 2D (direction) and 3D (torsion) coils. The search coils have been tested successfully in a number of research laboratories in Europe and in the USA. They are certified as medical devices according to the European CE regulations. To this end CHRONOS VISION maintains a quality management system that fulfils the ISO 9001 and ISO 13485 standards.

CUSTOMER SPECIFIC DESIGNS
On requests, CHRONOS VISION manufactures customized scleral search coils e.g. embedded black markers for simultaneous measurements of three-dimensional eye movements using videooculography. For further details or special needs please contact us at
eye.tracking@chronos-vision.de!