Determine PLC

The following explains how to determine a PLC for a specific lens. This is useful when you want to take the PLC from one database and enter it as a SRG (surgeon entered) constant in another database.

Using SOAP set the selection criteria

Then look at column 3 and 4 in the SOAP PREDICTION ERROR chart. If there is a PLC then they will be equal. If they aren't equal then there is not yet enough data to calculate one. In this case below the PLC is 5.316 for lens AA-4203V*.

If you are moving to a new, empty database and the PLC for the lens that you are looking at in the old database has not clicked in because there is not enough statistical significance or fewer than 20 cases, then look at the Standard Error in Column 4. If it is near 0.10 mm and there is nothing special about the cases (random), then use the PLC in column 4 because it is yours, not from a group of surgeons. In the screenshot above the STANDARD ERROR is 0.034 which is much less than 0.1 because in this case there is a PLC. If the STANDARD ERROR is much greater than 0.1 then you shouldn't enter a SRG in the new database. You should just use the MFG (Manufacturer) which is already built-in to the lens database in HICSOAP.