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J. Paetzold, T. Will, E. Krapp, K. Porubska, U. Schiefer; Internet-Based Data Transfer of Visual Field Tests Obtained With the Humphrey Field Analyzer (HFA II). Invest. Ophthalmol. Vis. Sci. 2007;48(13):958.
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© ARVO (1962-2015); The Authors (2016-present)
(i) To transfer pseudonymized HFA II (Carl Zeiss Meditec AG, Jena, Germany) records by Internet to a central server of a visual field reading center (VFRC) and to avoid mailing of floppy disks, (ii) to allow an immediate on-line response, (iii) to develop an on-line archive and (iv) to provide electronically available numerical threshold and total deviation probability values.
Visual field tests of each patient were recorded as usual on a floppy disk. A central web server with a usual LAMP (Linux, Apache, MySQL, PHP) installation provided a password protected user interface for uploading all database files of a HFA floppy disk with any up-to-date web-browser (comparable to the uploading procedure when submitting a paper or an abstract). With a special extension to the Internet Explorer for Windows (Microsoft, Seattle, USA) we were able to simplify the upload procedure even more: All 9 database files on the floppy disk were selected and uploaded automatically. With the c-tree database software (FairCom Corp., Columbia, MO, USA) it was possible to read the original database files of HFA floppy disks already on the central server. This allowed immediate on-line checks of examination data. In the VFRC the data were copied to floppy disks again. These were processed by an HFA IIi instrument (with firmware version 4.0), which created a high resolution bitmap file of each examination printout and a serial interface export file. These files were also transferred to the central server and used for the extraction of numerical threshold, total deviation, pattern deviation and probability values.
Up to now more than 600 visual field tests have been transferred and stored on the central server of the VFRC without problems. Participating sites with access to the Internet were able to send their visual field test results to the VFRC from anywhere in the world and could immediately check the results of the quality control, provided by the VFRC on the web site. HFA II visual field tests were available electronically for further analysis in the VFRC. The original data from the floppy disks were not altered by this procedure.
The Internet-based transfer of HFA visual field test data avoids the mailing of floppy disks. This is of special interest for multi-center studies. It simplifies and accelerates the data transfer remarkably. This is a first step on the way to collect HFA records in a central database for further processing of numerical visual field data.
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