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Alcon AcrySof Toric IOL.

Clicking on the link below will automatically download the program onto your computer.

Surgically Induced Astigmatism (SIA) Calculator.

alcon intraocular lens implant

Surgically Induced Astigmatism
        Calculator SIA Calculator — SIAC_104.xls (Microsoft Excel)

This Surgically Induced Astigmatism Calculator (SIA Calculator) has been designed to calculate, by means of vector analysis, the amount of surgically induced astigmatism created during the cataract surgical procedure. Please feel free to download this calculator, place it on your computer and then add cases sequentially.

Windows: Microsoft Office 200, or later is required. In order to run the SIA Calculator application the Macros must be enabled. (Choose Tools> Macro > Security and choose High for a signed macro.)

Macintosh: Office 2001 for Mac or later is required and Macros must be enabled. Detailed instructions can be found under the instructions tab of the SIA Calculator download.

When entering patient data into the SIA Calculator, it is always best to use the same instrument for pre and post-op keratometry measurements. Manual keratometry or autokeratometry is preferred over simulated Ks. Also, please take care not to flip the pre and post-op meridians. Pre and post-op data should be entered in the corresponding steep or flat meridian. After cataract surgery, the axis in each of the two principal meridians should only shift between 5 degrees and 20 degrees; and, unless a very large incision is used, the power change should be less than 1.00 D.

Keratometry measurements are typically between 35.00 and 50.00 diopters. Measurements outside this range are unusual and should be re-verified. Axis measurements must be an integer between zero and 180 degrees. The axis of the steepest and flattest meridian should differ by 90 degrees +/- 5 degrees. Values outside this range may indicate irregular astigmatism and should be re-verified. The incision location must be an integer between zero and 360 degrees. Look at the picture under the SIAReport tab for a graphic representation of the convention for incision location.

This individual patient information will be automatically summarized in the SIA Calculator by incision type, size, and location by using the built-in "Create Report" function.

After you have enough cases to generate a report, the magnitude of surgically induced astigmatism will be visible under the SIAReport tab. This information can then be entered into the "Surgically Induced Cylinder (SIC)" field of the Alcon AcrySof Toric IOL Calculator (acrysoftoriccalculator.com/Country.aspx).

A tutorial for its use can be viewed by clicking on the "Tutorial" menu item at the bottom of the calculator page.
Cataract Surgery Arizona
Alcon AcrySof Toric
    IOL Calculator PLEASE NOTE

Dr. Hill requests your assistance in putting together a database of information collected from surgeons around the world to be included in an analysis of surgically induced astigmatism. These data will be analyzed in total, so that we may further understand surgically induced astigmatism. If you would like your data to be included in this important analysis, please upload your SIA Calculator information to the database. Instructions for sending data can be found under section VII (Send Data). Please note that no patient names will be sent to the database.


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East Valley Ophthalmology
5620 East Broadway Road
Mesa, Arizona 85206

Tel: +1-480-981-6111
FAX: +1-480-985-2426

Arizona's Top Eye Doctors - East Valley Ophthalmology provides this online information for educational and communication purposes only and it should not be construed as personal medical advice. Information published on this website is not intended to replace, supplant, or augment a consultation with an eye care professional regarding the viewer/user's own medical care. East Valley Ophthalmology's disclaims any and all liability for injury or other damages that could result from use of the information obtained from this site. Please read our full Terms, Privacy, Infringement

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