[visionlist] Elecrophysiology

[Michael Bach]

Dear Lai:

> I am a postgraduate student on early detection of glaucoma. I am  
> currently running various experiments on the Veris system (EDI).  
> One of the problem I have now is in the extraction of  the data I  
> have collected. Is there anybody out there who have knowledge on  
> the system? Thanks


0. You are aware, that using standard mfERG stimulation the mfERG  
isn't much useful in glaucoma? Special techniques may, and of course  
the mfVEP.

1. For the data, use the "export processed data" menu item (selecting  
long analysis intervals beforehand to allow for optional signal/noise  
assessment, you can always shorten them later). The resultant file is  
simply time (in rows) times signal channel (in columns) and can be  
easily read into a matrix (we do it using Igor Pro, I can send you a  
program excerpt).

The relation of channel and position in the visual can be deduced, it  
depends on the stimulus of course.

The file format does not depend on the VERIS versions I have tested.


2. for the meta data (subject name etc): this sits in the resource  
fork of the VERIS files. I am using a kludge to read the resource  
fork via AppleScript (calling the shell) in OS X, which knows about  
the positions where to expect the various ASCII bits. I can send the  
source code for that too, but it might need to be adjusted for the  
VERIS version (I do not have the underlying resource description, I  
guessed it from Hex dumps).



Good luck with your research, best, Michael.
-- 
Prof. Michael Bach PhD, Ophthalmology, University of Freiburg,  
Killianstr. 5, 79106 Freiburg, Germany.
President of ISCEV <http://www.iscev.org/>
Visual illusions:  <http://www.michaelbach.de/ot/>