BESST II IOL POWER CALCULATOR                                    


STEP 1: download here the latest version of the program.

STEP 2: read the “Installation Instructions” below.

STEP 3: fill in the Application Form to receive the activating Site Key.

Download latest version:

  1. BulletBESSt_2.0.0.76_Setup.exe

BESSt 2.0 WARNING:  Spherical Aberration

  1. We have recently discovered that different Pentacam units display the value of the Anterior Surface Spherical Aberration in different ways (either as an index expressed in e-3 or in microns), depending on whether an engineer has made a special calibration in situ or not). We are working out a conversion factor so that either value can be entered in the future, but for the time being, as the differences can be significant we recommend all BESSt 2.0 formula users (both Myopic and Hyperopic algorithm) to enter 0 (zero) in the Sph Aberr field in order to avoid possible errors in the calculation. When in doubt about the calculated IOL power please compare the results with the old algorithm (BESSt 1.0) and with different formulas if available. Please check this site again in a few weeks for possible updates.

Important note for users of versions prior to the current version is not compatible with databases created with versions before the release. If you want to keep the old database, you will have to Export the database into a csv. file (use the Export function) before installing the new version. Keep this file in a safe place and install the new version. Then open the .csv file, check if the input values are correct and copy all the input values onto the Import.csv file located in the working directory where you have installed the new version. Now from within the program you will be able to import the old database using the Import function.

View Presentations:

  1. BulletBESSt II - Direct Import (Full Presentation).pdf

  2. BulletBESSt II - Direct Import (Results Only).pdf

View Tutorials:

  1. BulletBESSt II - Direct Import (Pentacam Settings).pdf

  2. BulletBESSt II - Direct Import (My First Import).pdf

Download Manuals/Pentacam Configuration Settings:

  1. BulletReference Guide BESSt 2.0 [1.7] (pdf file)

Download Handouts:

  1. BulletBESSt© 1.0 Outcomes Handout (pdf file) [old]

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Hardware and Software Requirements:

The software runs on Windows 7, Vista, XP. Hardware requirements are minimal and it should run on any computer. You should run it as the administrator. No Mac or Linux versions are currently available. Eye Pro is available for mobile platforms such as iPhone/iPod Touch/iPad.


  1. 1.Download the latest version of the program by clicking on the link above and save it on your PC.

  2. 2.Install the program on the PC of your choice by double clicking on the Setup icon.

  3. 3.Launch the program (Start/All Programs/BESSt).

  4. 4.Take VERY CAREFUL note of the SITE CODE (what is it?) that will appear. To avoid mistakes it’s best to select it all with a double click of the mouse and COPY IT (shortcut Ctrl+C) in the computer memory.

  5. 5.Fill in the Registration Form present in the “Apply for License” section of the website (do not start the registration process until you have obtained the SITE CODE). Now PASTE (shortcut Ctrl+V) the SITE CODE in the appropriate field and submit your Form.

  6. 6.Upon payment receipt we will send you the Full Version SITE KEY by email, so that you can unlock the program. Please allow a few working days.

  7. 7.When you receive the SITE KEY by email, select it all with a double click of the mouse and COPY IT (shortcut Ctrl+C) in the computer memory. Then launch the program and PASTE IT (shortcut Ctrl+V) in the appropriate field.

  8. 8.Congratulations, the Full Version is now active!


  1. Please refer to the Frequently Asked Questions (FAQ) section.


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