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Carl Zeiss Meditec IOL Master
Cataract Surgery Arizona

IOLMaster — Lens Constants.

Optimization of Intraocular Lens Constants

IOL Master I KEY

I key, or the button pictured above activates the IOL Calculation mode.

Selecting Lens Data

The lens data available in the database may be optimized by the following procedure.

  • In the Options menu, open User Database. Select the respective eye surgeon and confirm your choice with OK.
  • Choose a lens. The input mask contains constants calculated from "Manufacturer's A Constant" or previously optimized constants.
  • Click on the OPTIMIZE button.

    IOLMaster Lens Constants

  • The dialog box for the selected lens will appear and the lens constants can be seen in the Basis column (Fig. 43, below).

IOLMaster Lens Constants

Loading Existing Data Records

IOLMaster Lens Constants

  • Click on the LOAD button to load the data records of all patients available for optimization.

IOLMaster Lens Constants

Special filter functions allow fast selection of patient data. The right column shows the list of all patients available for optimization (Fig 45, above).

  • Click on the desired patient data record in this list to select it.
  • Select the eye (OD or OS) to be used for the optimization calculation. The fields below show the measurement data of the IOLMaster.
  • If you wish the data of the other eye to be kept in the data table for further optimization, check the box marked: keep other side in table.
  • Click on the << button to load the selected data record in the left-hand table. These data records are intended for IOL optimization
  • Transfer at least 11 data records into the left-hand table in this way.
  • Click on the >> button to return the selected data record to the right-hand table if it is not to be used for optimization, but should be kept for possible later use.
  • Click on the Erase button to irrevocably delete the data record to the right or left.
  • When all the desired data records are loaded into the left-hand table, press OK to return to the optimization box (Fig. 44, below).
  IOLMaster Lens Constants

IOLMaster Lens Constants

  • Further patient records can be added to the left-hand list for subsequent additional optimizations.
IOLMaster Arizona   Note
The data contained in the database (right- and left-hand table) will not be deleted automatically and are thus available for later additional optimizations. A backup should be made at regular intervals by transferring data to an office management system or a printout.

Entering New Data Records

  • To enter data records which do not exist on the IOLMaster result table, click on the New button.

IOLMaster Lens Constants

This will bring up an input mask for creating a new data record to be optimized This data record may be used for optimization only, not for IOL calculation. Nor does it appear in the patient database.

IOLMaster Lens Constants


IOL Master warning WARNING: Only data obtained from the IOLMaster may be entered in the fields for pre-operative data.

When entering the refractive power, make sure that the same keratometer refractive index is set on the IOLMaster as is on the keratometer used for the measurement.

The entry of data taken from ultrasound devices will yield incorrect results.



IOL Master warning WARNING: The data records of patients who have undergone refractive surgery of the cornea should be excluded from optimization.
  • Complete the entries in the input mask.
IOLMaster Arizona   Note
The entry of the Exam date is essential! Entry of ACD, Surgery Date and Post-Op Date is optional.


IOLMaster Arizona   Note
There should be a period of at least 8 weeks between the surgery and post-op dates. However, this period will not be checked!
  • If you wish to reject the entries made and return to the optimization calculation mask, click on the CANCEL button.
  • To confirm the new data record and add it to the list of data records to be used for optimization, click on the OK button. The new data record is shown in the Data Records field. It is displayed in the list of data records.

Entering post-operative data

  • Highlight the patient data record by clicking on it.
  • In the IOL (D) box, enter the power of the implanted IOL.
  • In the Post Op Ref box, type in the post-operative refraction.
  • The entry of Surgery Date and Post-Op Date is optional. When entered, however, the data will be checked for plausibility.
 
IOLMaster Lens Constants
IOLMaster Arizona   Note
There should be a period of at least 8 weeks between the surgery and post-op dates. (This period, however, will not be checked!)


IOLMaster Lens Constants

  • Complete all selected patient data records in this way. The number of data records containing IOL and post-op ref data and the total number of loaded data records is specified in the Data Records box.

    The boxes beneath it show the number of data records in the specified axial length ranges.

Once all IOL and post-op data has been entered, the requirements for the optimization calculation have been met.

  • Patient data records appearing on a white background contain all the data required for optimization
IOL Master warning WARNING: If a patient data record is highlighted in red, the IOL and/or post-op ref data has NOT been entered, or a measured value (AL or KER) is missing.

  • If a patient data record is highlighted in yellow, no ACD values exist as yet for this data record, and the a0 (Haigis formula) is not optimized with these data records.
IOLMaster Arizona   Note
Only the a0 can be optimized with the IOLMaster software for the Haigis formula. For the optimization of a0, a1 and a2 (more than 200 data records required) please send this clinical data to Carl Zeiss Meditec.

Starting Optimization

  • Start the optimization calculation by clicking on the Optimize button. Depending on the number of data records to be processed, the computing process may take some seconds.

The optimized lens constants will now be displayed in the New column.

IOLMaster Arizona   Note
Data records with an IOL power of 0 D will not be included in the optimization process.

The optimization calculation supplies lens constants for every patient's data record, based of the measured values and results of surgery.

 

IOLMaster Lens Constants

IOLMaster Lens Constants

The mean value (sum of all lens constants divided by the number of patients) and standard deviation are then calculated. Lens constants that are more than double the standard deviation are excluded from the optimization.

If less than 11 data records exist for optimization or data records are rejected (0 D), - - - will appear in the New column. In this case the optimization has failed. Repeat the optimization process with a larger number of data records, or perform several optimizations for various groups of eyes (e.g. short, normal, and long eyes). This procedure also ensures a higher degree of accuracy in IOL power calculation.

The resulting mean value will be displayed as an optimized constant. To obtain optimum constants, patients with pre-, intra- or postoperative complications which could affect the refraction state should be excluded.

IOLMaster Arizona   Note
The displayed a0 value does not take into account the data records highlighted in yellow!
  • To reject the last optimization run, click on CANCEL. In this case, the optimized constants will not be saved to the lens data base, even if a new data record has been entered.
  • Confirm the newly optimized lens constants by clicking on the << button to the right of the Basis field. In this case, all optimized constants will be accepted. If you wish to accept only a specific constant only (e.g. a0), click on the << button to the right of this constant.

IOLMaster Lens Constants

  • Click on OK to return to the User Database. Optimized lens constants will only be saved to the lens database and for use in future IOL determination if they are confirmed with OK.
  • Click on OK to return to the IOLMaster main module.