Specification

For Eye-Care Professionals

For Pediatricians

For Researchers

Neucodia System Functions and Specifications

  

Neucodia is a noninvasive, objective medical device that can be used in clinical practice, hospitals, and research laboratories for quick and reliable assessment of visual function. It is a novel electroencephalographic (EEG) device that provides select stimuli, synchronized data acquisition, amplification with adjustable filter settings, rich data processing tools in time and frequency domains, and statistical analyses. It is also equipped with a mouse-driven graphical user interface and automatic outlier removal algorithms, which facilitate easier, quicker, more accurate and reliable measurements of visual evoked potentials (VEPs) and pattern electroretinograms (PERGs).

   

Neucodia has 510k clearance from the FDA and is fully compliant with ISCEV standards.

Users: Ophthalmologists, optometrists, vision researchers, neurologists, and trained technicians.

Patients: Individuals at-risk for visual pathway dysfunction or with confirmed ophthalmic or neurological disorders.

Environments: Clinical offices, hospitals and research laboratories.

Power supply:           110/220 V AC, 60/50 Hz, 5.5 Amp (110 V)

Stimulus generator
Neucodia includes a 17” CRT or high-speed LCD flat-screen display. The CRT monitor has a maximum refresh rate (frame rate) of 150 Hz, which is capable of generating high frequency stimulus modulation. The stimulus generator is configured with 8-bit or 16-bit grey levels for fine luminance modulation. A user-friendly graphical interface is provided for display calibration. Linearization of luminance is achieved through generation of an individualized look-up-table (LUT) for gamma correction. Neucodia is shipped with a stimulus generator calibrated by the manufacturer. The stimulus can be virtually configured for any type of pattern, variety of temporal frequencies, spatial frequencies, luminance levels, contrasts, and sweep functions.
  
Stimuli can be easily configured to different sizes, colors, temporal frequencies, spatial frequencies and virtually any pattern. Sweep stimulus display (a serial of stimuli displayed in timely sequence) is also available.

Amplifier 
Model:                                            fafe -20
Channels:                                        1 and 4 differential channels
Gain:                                              20,000
Bandwidth filter:                               0.5 – 100 Hz
Optional:                                         Customized gain and bandwidth
Common mode rejection ratio (CMRR):   > 120 dB
Input Impedance:                              2x1012 Ohm
Isolation voltage:                              1.5 kV
Input noise:                                     1 mV p-p (10 Hz)
Input range:                                     + 25 mV
Power supply:                                   +8 - +15 VDC
Connector type:                               1.5 mm Male Safety jacks

Data acquisition

Neucodia is equipped with a 12-bit, 8-channel analog-to-digital converter. Data sampling is synchronized to the stimulus display’s frame rate. Thus, samples are taken at the same time points in the stimulus frame interval. The data collection rate can be set to 1–10 samples /per frame with a maximum sampling rate of 600 Hz per channel.

Data processing and display

Users can select a variety of data processing tools for automatic calculation and display of results immediately following the test.  Analyses include the following techniques: discrete Fourier transform, spectral analysis, digital filtering, peak detection, multi-variate statistics, frequency band analysis with calculation of magnitude-squared coherence (MSC), outlier removal, T2circ signal-to-noise calculation and visual acuity estimation.

   

Steady-state responses

Frequency components of interest (FCI) are displayed in both sine-cosine plots or amplitude and phase plots.

 

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amp-phase-plot.gif

In a sine-cosine plot, the means of the FCI (for each step) in a sweep function and corresponding confidence circles (95% or 90%) calculated using T2circ are displayed.

In an amplitude or phase plot, the means derived from the FCI for each step in a sweep function and corresponding confidence ranges (95% or 90%) are displayed vs. the sweep variable (e.g., temporal frequency, spatial frequency, luminance contrast).

Transient responses

For a transient response (averaged VEP or PERG signal plotted vs. time), the program will automatically detect the peaks within six time windows set by the user. Also, users can place two cursors to read the amplitude and time values of marked points, and they can perform filtering of the response in the frequency domain. The entire waveform is quantified by calculation of magnitude-squared coherence for each frequency component and for bands of frequency components. 

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Test configurations

All the testing protocols and stimulus conditions are easily set through graphical menus. The configuration parameters are saved in configuration files. Users can load the pre-configured parameters for the test to be performed.

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Noise monitoring 
Neucodia displays real-time EEG signals on the user’s screen to monitor the status of electrode connections and the environmental EMF noise. If excessive noise is present, it indicates that either the electrode is loose or that there is significant EMF noise in the testing room that might affect the test results.

Software

Neucodia uses Microsoft Windows 7 as a software operating system. Data files are in text format and easy to be exported to Excel or other spreadsheets. Display images can be saved in either bitmap or JPEG format.  

Fixation monitoring

Neucodia equips with an infrared camera, source, and display to monitor the observer’s fixation during tests.