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pondelok 16. apríla 2012

Synergeyes Duette NEW AND IMPROVED Fitting Method

Last week I had the benefit of attending a presentation on the most up to date recommendations for fitting the Synergeyes lenses.  For new ODs out there just getting familiar with this lens, I have been promised that this new method can simplify your fitting time to around 15 minutes on the initial day and 1 to 2 follow-up appointments.  Believe me, this is considerably less chair time than what it has been taking me to perfect the lenses since I began fitting larger numbers of patients in December.

Here's the idea:  Mid-K fitting.  To summarize the words of Dr. Beatty (who gave the presentation), "fit the RGP like a hard lens, and the soft skirt like a soft lens."  Makes so much sense...

1) Determine K's, then find the average K value (mid-K value).
I usually just use my autorefractor and average the K's from flat and steep.  Remember, in order for this lens to work you can't have more than 1 diopter of residual astigmatism, so K values and corneal cyl are really important to evaluate before even opening your trial set.  I was told that if the patient has less than 1 diopter of corneal cyl, you should add 0.50 D to your mid K value.

2) Use the Synergeyes conversion table to select the appropriate base curve for your Mid-K value.
Find your mid-K, go across the table to find the base curve in radians.  Remember, the Synergeyes lenses only come in a few base curves (7.9, 7.7, 7.5, 7.3).  Round your conversion value to the nearest available base curve.  Example: if your K value gave you 7.46, select the 7.5 base curve.

3) Insert the appropriate lenses on each eye, using the medium skirt curve.
NaFl staining should look like this, but it pretty much always
does unless you are really off on base curve.
For first time wearers, it works best for you to insert the lens yourself.  I have found that fluorescein really doesn't tell you much on these lenses unless you are super flat or steep, so I would skip that step if you feel comfortable looking at RGPs with a slit lamp.  To save on time, have your tech insert the lenses for you.  You need to let the lenses settle at least 10 minutes before evaluating to truly judge the fit.

4) Over-refraction
All the fitting set lenses are a -3.00, so you have to over-refract to find the correct power to order.  Patient will tend to want to overminus you in this lens, so make sure you fog well, or do retinoscopy.  Your final lens should be within -0.50 to -1.50 more minus than the spherical spec Rx.  This is different from the original fitting recommendation, allowing more minus!  It has been recommended that you let your patient wear the trial frame of their Rx around the office before they leave so they can see what their distance and near vision will look like.

5) Slit Lamp Evaluation
Waiting that 10 minutes is going to help you evaluate the soft lens skirt to make sure it is not fitting too tightly.  Originally, the Synergeyes lenses were recommended to be fit with a steep skirt when comfort or vision problems arose, but we now know that movement of the lens between blinks is essential to fit and comfort.  If you have a medium skirt on the patient and you don't see movement with blink, then you need to order a flat skirt.  Changing the skirt should not influence the over-refraction.  I have seen patients come back a week after their initial lens was dispensed with a ring around the cornea from the skirt fitting too tight, so make sure the lens is moving!  It will only get tighter as it dries out during the day.

6) Duette Multifocal Add selection
Ghosting creates almost a "3D" view for near
This is normal with this lens
For presbyopes, there are 2 add powers available: small and large.  The new method recommends starting with small adds in both eyes.  This is especially true for early presbyopes. If near or computer vision becomes an issue, try going to a large add on the non-dominant eye. I was told that a large add in both eyes is really reserved for late presbyopes.  I think this is different from original recommendations as well. Educate your patients to expect to have that "shadowing" or "3D ghosting" effect that so many multifocal wearers describe.  If you prepare them for it, they won't think of it as a problem inherent to a bad fit.

7) Insertion and removal
Check out the company's videos here
Always fill the bowl of the lens before inserting.
Best to insert the lens with your face parallel to the floor.
Remove the lens by pinching the soft skirt between your fingers below the center of the lens, and then lifting up and out to break suction
Use Biotrue or Aquify solutions.  Clearcare for heavy depositors.  See this post for more info.

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