A PeriData database is one file with the extension .PHF It contains the original visual field results together with the patient name in "fixed format" and is very compact. The associated index file with the extension .PHD is automatically created and automatically regenerated in case of loss or damage. The sorting can be changed.
An unlimited number of PHF databases with any file name is possible. PeriData can open with several databases simultaneously. Examinations can be transferred from one database to another (with copy and paste).
In the LINK MODE, each patient gets his unique database file, that contains only his data. The EMR software defines the database path and file name with the call using the command line parameter /FILE. Usually, the EMR software generates the file name from the ID (z.B. 00012345.phf). Recommended path name: ../PeriDataFiles/
In the normal mode, the user creates new databases using the menu "File > New". The preliminary name is NONAME...phf. When the database is closed, the user defines the name and path. The path should be on a PC with a regular backup (server).
Several mechanisms can open a database when PeriData is started. There is a priority list, to assure that only ONE database opens:
1. Link Mode: The specified database (of one patient) will open .
2. App was started from the explorer with a double click on a PHF file: this file is opened.
3. App was started with a command (batch file) and the first parameter is a readable path: this PHF file is opened.
4. A file named "PeriwinStandardDatabase.txt" is located in the exchange folder: The first line is read. If it is a readable path, this PHF file is opened. The TXT file has to be created manually.
5. Option "Load last file" is set: The 1st database file in the "recent files" list will open.
The simultaneous access to the same database is allowed and an important feature of PeriData. Only the workstation that opens a database at first will obtain full read and write permission. This is a Windows rule ("first come first served"). The following workstations get the title text [readonly]. And the icon is crossed-out.
To prevent a blocking of data transmission, all workstations without perimeter connection, that do not import data, should be set to "Viewing Mode" (menu extras > options). Workstations running in Viewing Mode open databases always in readonly mode. The perimeter workstation gets full write permission.
If a database is open on several workstations, and the examination list has changed (e.g. new examinations received at the perimeter workstation), the other workstations get an update message. In the Link Mode, the message appears at once, otherwise when you click into the database window.
It is strongly recommended to work only with the original files. The use of copies and the moving of files may cause errors and - in case of multiple access - data differences. In the normal mode, when one large database file is stored on the perimeter room workstation for speed reasons, this local directory is shared with the other workstations. Do not forget to copy the file once a day to a backup folder on the server.
<...>.PHF: contains all data. Per examination 1280 byte (fixed format).
<...>.PHD: associated index file. Generated automatically. Per examination 57 byte. The index file is needed for a quick build-up of the examination list and a quick search function. It is located in the same folder. In case of loss, it is reconstructed automatically. In case of corrupted data, it can be reconstructed on demand (Menu Extra > REPAIR).
Deleted examinations are only marked in the PHD index file in a first step. In a second step (Menu Extra > CLEANUP), the examinations are deleted in the PHF data file and the file is packed. This function is offered automatically when the database is closed. Small databases are cleaned up immediately without asking.
Maximum size: 64,000 examinations = 82 MB (PHF file). For safety reasons, it is recommended to keep the file size much smaller. The best solution is the combination with an EMR (electronical medical record) system.
The data are upwards compatible since more than 30 years. The downwards compatibility is limited. Data can always be read, but it may occur that an examination that was stored with a newer version is displayed incorrectly with an older version.