Question about slab-off

I deal with slab-off EXTREMELY infrequently, and we just had a dispense with a patient that went well in the office. But when she got home, she stated that on the OD lens, right at the line, she was seeing a "wave" or "distortion" effect in her TF reading area (I think it's the reading area, she was not very clear if it was reading or intermed). Is that typical with a lined trifocal with slab-off, where the pt would see a visual distortion? Rx as follows:

-4.00 -2.00 x 100 +2.75
+1.00 -0.75 x 090 +2.75

CR39 TFF7x28 Polarized

This patient is also crazy in that she had a TF set at FT height prior to this and requested "that we put it where it normally would go". So I'm not sure if this is because she doesn't like the TF too high, or if there's something with the lens geometry that she's seeing that I just don't have the experience to remember/check for

Lots of questions. How long has she had this lens? Did she just complain the day she got it, or has this been going on for a week plus? Also, has she had a slab before or is this a first time? If this is her first slab, did she have surgery? Why is it her first slab?

If the lens is polarized then the filter could be the cause of the distortion, but why would she be in a polarized lens? Is this the only pair, or does she have a clear lens with the slab off? Is this her first slab off?

She just got em yesterday, they were fine enough in the office, but drove home w/ her old pair on as it's a hell of a change, then when she got home is when she noticed said distortion. Reason for the Rx disparity is, I believe, due to cataract surgery with an ophthalmologist in the OS (evidently it did not go well, from what my OD relayed of what she was saying in the chair). This is the first slab-off (her Rx prior to this fell into a much more typical range of disparity between the eyes).

She requested polarized because that's what she had in her pre-cataract TFF suns. We have a clear pair coming (also with slab-off), but they haven't arrived in yet.

Is her vision ok other than the distortion? Until she get's her clear pair and wears them constantly she will notice that distortion, I would have suggested waiting for her to have both dispensed at the same time due to the change in her RX being what it was, including the addition of the slab-off

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Originally Posted by Optical Roy

Is her vision ok other than the distortion? Until she get's her clear pair and wears them constantly she will notice that distortion, I would have suggested waiting for her to have both dispensed at the same time due to the change in her RX being what it was, including the addition of the slab-off

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Yes! I would always recommend they wait for the clear pair to come in first. It will be easier to get used to them when they have 2 pair that are the same. Also, start wearing them early in the am is easier to get used to a drastic change. Anyone who has a huge change should expect it to take time to get used to. She should have been warned by OMD and optician when ordering that it is a drastic change. I make it a point to warn all my patients when they have noticeable changes. It makes it easier on the patient and myself.

Is this an old school slab off with a sharp line, or one of the new freeform slab offs? IMO the latter suck, bad, and could be described as a blurry wave across the lens. Was the lens checked to make sure the slab line was lined up with the segment line and not below it?

She was definitely alerted to the fact that these glasses will be DIFFERENT as all heck compared to what she's used to and that there will be an adaptation period. I don't know why we didn't wait for the clear pair to come in, because typically we do. Maybe a lens B/O? Not sure. I unfortunately didn't get a chance to see them at check-in, I was only able to let her know what she was likely experiencing after the dispense, over the phone. I THINK the vision is ok for her, all she mentioned was the bit at the line. Again, if that's at the intermed or the reading, she wasn't very clear

You need her to bring in the glasses so you can look at them.

The issue should be visible to you.

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Originally Posted by juno

I THINK the vision is ok for her, all she mentioned was the bit at the line. Again, if that's at the intermed or the reading, she wasn't very clear

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Juno, I've seen coatings build up and 'run' at the segments that would match the symptoms- pretty easy to see when held up to the light. However, it's not that common with the better coating systems, although the slab might have required a lower quality coating system. IMO, worth a look.

Hope this helps,

Robert Martellaro