CHRONOS VISION manufactures medical devices of highest quality for the measurement of eye movements. The products contribute significantly to successful refractive surgery and find application in clinical research and diagnostics. Drawing from the experience and knowledge of Prof. Clarke and his research group at the Vestibular Research Lab of the Charité Medical School in Berlin, CHRONOS VISION has designed and developed a number of eye tracking systems and distributed them worldwide for use
in research studies and clinical diagnosis. This background knowledge of the
oculomotor and vestibular systems has been the driving force for our innovative products. It has also provided CHRONOS VISION with an edge on the competition.
In addition to the manufacture of its own products CHRONOS VISION has gathered considerable knowledge through the development of numerous customer-specific software solutions.
Virtual SVV™ (subjective visual vertical)
Light-occluding head unit with position sensor for indicating the luminous line & handset to the line orientation for the patient
Base station with charging function & Virtual SVV™ software for control and evaluation of the examination
Graphic display of measurement values in the software & clearly arranged findings sheet with export function
What is meant by "Subjective Visual Vertical"?
The orientation of the head relative to gravity is constantly signalled from the otolith organs – above all by the utricles – to the central nervous system. The otolith organs function so that any linear acceleration displaces the otoconial mass and accordingly shears the embedded sensory hair bundles against the otolith maculae. This results in a potential change in the sensory cell and consequently a change in the afferent discharge rate of the cell. As a result the individual is able to accurately estimate the socalled Subjective Visual Vertical. The estimation of the SVV thus serves as a diagnostic indicator of utricle dysfunction.
What is the Virtual SVV™ system?
The compact system is composed of a light-occlusing head unit for displaying a luminous line, and a hand-held device for the vertical orientation of the line to the patient. The clinically-proven software allows the physician the control and evaluation of the individual measurements. Thanks to the integrated battery and a wireless connection to the PC, the device offers maximum freedom of movement in practice.
What purpose does the Virtual SVV™ serve?
The Virtual SVV™ is intended for use in the diagnosis and rehabilitative therapy of vertigo patients in the ENT or neurology clinic. It can also be employed for screening purposes by specialists in occupational safety.
How is the patient tested?
With the Head Unit mounted the patient remains in total darkness. This is of critical importance since the patient’s estimate of the vertical is based on the information from the otolith organs. Any visual cues in the vicinity are likely to produce incorrect findings. The operator initiates a measurement and the luminous line appears at a random angle on the patient’s display. Using the buttons on the Hand Controller the patient then rotates the line to vertical and confirms the setting with the OK button. The difference between the set angle and the head tilt angle is then recorded. This procedure is repeated three to five times for each head tilt
Which tests are possible?
The Head Unit is fitted with movement sensors in order that SVV testing can be performed at arbitrary static tilt angles and during varying levels of unilateral centrifugation. The measurement and evaluation software accommodates these variations in test mode parameters.
The Virtual SVV™ is distributed by Interacoustics, more detailed information can be found on the Interacoustics product page.
Virtual SVV™ benefits
- Compact device for the functional test of the otolith organs
- Wireless communication to the PC for maximum freedom of movement
- Easy handling and quick implementation
- By light-occluding head unit no darkening of the room longer necessary
- Mobile measurements in the clinic, ambulant or bedside
- Maintenance-free acceleration and rotation sensors for accurate measurements in any position
- Comfortable serial measurement
- Angular resolution of 0.1 °
- Wireless range up to 10 m inside buildings
- Integrated into OtoAccess™ database
The OneK + eye tracker is a
high-speed camera for measurement of eye position throughout refractive surgery.
The entire image processing architecture is a combination of image sensor, A/D-converters and general-purpose image processors on the same semiconductor chip. The built-in processor array handles a full row of pixels in parallel.
The OneK+ with integrated DeyeRECTOR.pupil module is completed by four other software modules.
Today, the problems of many patients suffering from poor eyesight are being
solved by laser eye surgery. Fundamental to the success and quality of LASIK
surgery is the high-precision control of the laser beam, which ultimately relies
on accurate realtime measurement of the position of the eye throughout the operation.
The OneK+ is a high speed eye tracker with realtime data output. The tracker was developed as an OEM component for device manufacturers of the refractive surgery and is designed around the SICK Ranger camera.
The image processing architecture is integrated into a compact housing. This consists of a combination of image sensor and multiple parallel RISC processors integrated on a single CMOS chip. The entire image processing algorithm for pupil tracking is performed in-camera. This configuration represents a standalone pupil tracker without need of any external computer. Furthermore, the camera’s small footprint facilitates integration into existing systems. On-chip image processing provides pupil tracking with latency of less than 1 ms. The flexibility of the hardware architecture enables user-selectable regions of interest (ROI) at frame rates beyond 1 kHz.
Considerable attention has been given to enhancing the performance of the OneK+ algorithm with regard to occlusions, instrument artifacts and spurious reflections.
- On-chip image processing
- Standalone pupil tracker
- Transfer of tracking data via RS485 at 1 Mbit/s
- Transfer of image data via GigaBit Ethernet
- Selectable frame rates of typically 100, 200, 500
or 1000+ Hz
- Uniform processing latency time of <1 ms
- Spatial resolution of the order of 0.01° respectively ≈ 3 µm
- Sensor resolution of
1536 x 512 pixel with free selectable ROI
- C++ API (DLL)
- Weight (without lens): 510 g
- Dimensions (L x W x H):
125 x 52 x 52 mm
- Supply power : 24 V
- Power consumption:
7W, 0.8 A
Power - M12, 8 pins, male
Ethernet - RJ45
Eye Tracking Device (C-ETD)
The Eye Tracking Device , deployed as a universal research tool onboard the International Space Station in 2004, is used for various European, US and Russian experimental studies into the changes in spatial orientation in zero gravity.
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. 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) .
The CHRONOS VISION Eye Tracking Device (C-ETD) is 2015 Space Technology Hall of Fame Inductee at 31st Space Symposium.
- 2D/3D measurement, monocular / binocular acquisition
- High image sampling rates up to 200/s for 3D and up to 400/s for 2D
- Measurement resolution
- Linearity < 2.5 % ± 20° H/V (< 4 % ± 20° T)
- Online display of eye images
- Disk storage of image data for offline evaluation
- Optional 6 degree-of-freedom of head movement sensors
- Synchronous acquisition of up to 31 analogue signals
- Frame sync output/event trigger input (TTL level)
- Thermoplastic facemask inserts for slippage control and subject comfort
- Standard data output formats for post processing (ASCII)
Scleral Search Coils (SSC)
2D Scleral Search Coil:
For measurement of horizontal and vertical position of eye in space
3D Scleral Search Coil:
For measurement of horizontal, vertical and torsional position of eye in space
Primelec Search Coil Tracking System
For many in the field of eye movement and oculomotor research the scleral search coil
techniques represent the
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.
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!
Search Coil Tracking Systems
Our partner Primelec manufactures and sells tracking systems for Scleral Search Coils for more than 25 years. Leading research institutes and universities all over the world use the Primelec system and benefit from their long-term experience and state-of-the-art knowledge throughout all these years. Primelec tracking systems are characterized by high resolution in combination with low noise. High output data rates are combined with user friendly handling. Eight recording channels, automatic tuning, configuration memory and a USB interface are additional features which complete the usability of Primelec systems. CHRONOS VISION Scleral Search Coils and Primelec Tracking Systems are mutually adjusted and fine-tuned, allowing high precision recordings of 2D and 3D eye movements.
More information about Primelec products can be found here.
- Use of medically approved silicone material
- Lead wires are free of solder joints
- Customer-specific designs on request