SIA

In Summer 2015 an update created some questions about SIA.

We recently updated our HICSOAP program and are running into some changes in the toric iol section that we would like some clarification on. With the old version we were able to type in the SIA D at .25 and our surgeons perform their incisions at 200degrees OS and 20degrees OD. With the new version this has changed. Please advise.

In the NEW VERSION OF THE PROGRAM you have the ability enter the SIA Magnitude and Axis as well as the INCISION LOCATION. Recent studies have shown the SIA AXIS is not always the same as the location of the incision … unless you know better they should probably be the same. If you always operate temporally and select the 2.5 mm small incision box, the PROGRAM will determine what the SIA is and use it for the calculation … it is the most accurate way to get consistent outcomes.

Good luck.

Jack.

P.S. The HELP Button at the bottom of the screen and at the top of the Main Menu always has the latest information, rather than a MANUAL.

We just updated to the latest version and my tech is noticing that the toric lens calc for the Alcon toric is asking for SIA, axis of SIA and incision axis. I think this is new and we’re not sure how to fill it in. We have calculated that the number for SIA is 0.25D agains that axis of the incision and so not sure why both SIA axis and incision axis are required. Also, it seems to use -0.25 as the default, I’m guessing so that the cylinder induced is 90 deg from the axis of the incision. Please explain.

You should be using version 2015.1005 (October 5th, 2015 or later). You enter the same value for SIA and Incision as you did before and the SIA AXIS is the same. So if you have been entering 0.25 magnitude and incision temporally in the left eye of 0, you would enter 0 for the SIA AXIS ALSO. It is the axis of FLATTENING. We are finding that the INCISION AXIS may not always be the same, so we have added these to allow the difference.

Also, on the SIRC CHANGES in the NOV 3rd version which will be released shortly, we have ADDED SELECTION CRITERIA (pic #1) that allow you to look at INCISION LOCATION and PRE EXISTING ASTIGMATISM to see the SIRC CENTROID which you can use. On the SIRC CHANGES SCREEN (pic #2), click HELP at the BOTTOM and it explains everything in detail (pic #3).

Pic #1 (click Pic to zoom)

Pic #2 (click Pic to zoom)

Pic #3 (click Pic to zoom)

I really need your help. Since downloading the new update, the Holladay toric calculator asks for SIA , SIA axis, and incision. The SIA axis is new from the old version and I don’t know what to type in there. It does not show the toric power (i.e SN6AT 3,4,5,etc). Please help guide me with this. Our charts are piling up. I am sure it is simple- it is just new to us. It does not show the axis line so we cannot type in the number needed to proceed

The SIA AXIS and INCISION AXIS are usually the same so you just use the values you did before for the incision and use it for the SIA AXIS (in the future you may find they are not the same). When you put in all of the values the LENSES will show up like before.

(click image to zoom in)

Our docs use incision site 180 for the OD , and 0 for the OS. The SIA will not allow us to type 180. We can type in 179 but not 180. When we type in 180 the box stays pink and it does not display the toric power such as SN6AT3,4,5, etc. If the values are not the same , will it affect the axis of the lens position? I am sorry. I just am confused.

For now use 0, since 0 and 180 meridians are the same, just like in glasses. The next version will allow the 180.

Where do I get the number that goes in the new SIA axis box when calculating a toric lens? Before the latest update I would always use .40 in the SIA box and incision at 155.

Put 155 in both boxes. As we go forward the actual SIA axis may not be located exactly at the incision axis.

Recently my boss, Dr. M asked to determine his surgically induced astigmatism (SIA). I ran the reports from HICSOAPPRO. The issue is HICSOAPPRO gives SIRC (Surgically Inducted Refractive Change) not SIA. If we were to use SIRC for his SIA we would be half a diopter or more off. Is there a way to get SIA from the software? Can SIRC be converted to SIA? To be honest I used the free online calculator from Dr. Hill (don’t tell Dr. Holladay). But it is a giant pain to have to upload data from one program to the online calculator especially when we use HICSOAPPRO for EVERY cataract surgery patient. So I am hoping you can provide some guidance. I found he manual online and while page 33 does address what SIRC is and what it does, it doesn’t really solve my SIA question. I know that the program asks for the SIA for the TORIC planner so I am hoping it can also determine it as well.


Dear Dr M: I have spent the last 2 years refining the Total SIA on the Toric Calculator. I had scores of surgeons and multiple incision locations for small incision cataract surgery (< 3.0) mm. See the attached article.

The Total SIA in the Toric Software is better than the Barrett Toric Calculator and anything else. As a result it has been added to the Alcon Toric Calculator so they get the best results. To determine this yourself you would need hundreds of cases with astigmatism at every axis as well as multiple incision locations.

All you need to do is check the SMALL INCISION Box and ENTER the EXACT MERIDIAN of the CATARACT INCISION (find out exactly where Dr. M operates in the Right and Left Eye). It accounts for everything as described below and gives the best results for Toric IOLs. Hills analysis and everything else is not even close. Try it you will see.