How about another head-scratcher! Problem: large change in cyl for elderly patient.

[andshewas]

Hi everyone,

I saw a patient recently who received a two-fold increase in her cylinder power due to corneal changes (Fuch's corneal dystrophy). She wears FT28 bifocals with anti-reflective coating.

When she first came to my office, the prescription she was wearing was
OD -1.25 +2.50 x005
OS -0.75 +1.75 x165
+2.50 add OU.

The new prescription her doctor had written was
OD -1.25 +5.00 x005
OS -1.25 +3.00 x155
+2.50 add OU.

The patient picked up her glasses some weeks ago and immediately complained of blurriness at distance and near. A coworker asked her to continue wearing them for a week or two, and to return if the blurriness persisted. Well, she came back last week and said that the problem hadn't improved. Given that the change in cylinder was so high, I recommended a prescription recheck.

She returned after her prescription recheck today with a very similar prescription and some recommendations from the doctor:
1) Raise the seg height;
2) Increase panto;
3) Reduce vertex distance.
Friends, I have a hard time believing that any of these adjustments will help my patient adapt to this prescription. (I adjusted panto to 10 degrees and reduced the vertex distance as much as I could given how the frame fits the patient; there was no perceptible difference to her.) However, there is one aspect of the patient's new glasses that I think may be the real culprit: the lenses are polycarbonate (chosen due to semi-rimless frame style and the patient's request for low cost). For most of the patients with high cyl who, for whatever reason, we've had to fit with polycarb, we have not seen or heard of problems with blur or distortion. However, since this patient is used to wearing CR-39 lenses, I think this might be what we're struggling with.
When fitting this new pair of glasses, we made sure to double-check her PD and take a pupil height measurement to minimize any issues that she would possibly face with the new prescription and material.

I'm thinking I will have to switch this patient's lenses to Trivex in order to still maintain low-enough cost, avoid the low Abbe of polycarb, and keep her in a frame style that she really likes. I do not have any full-rim frames that she found acceptable at the time of her original order. Do any of you have other suggestions as to what may help this patient adapt?

Thanks!

[bretk0923]

From my experience with the CR-39 to Polycarb switch, it never seems to go well. If you've done these adjustments and there is little to no noticeable difference for your patient, I would follow in the same footsteps, in switching her over to Trivex. Barring that, maybe the doc needs to ease her into a large cyl change? I've seen that done before, but I'm no expert there as to how that would affect her acuity.

Where's Quince? "Have I told you today how much I hate poly?"

[andshewas]

Haha! Yeah, Quince, give us your $0.02!
I'm not a poly fan, either, but I was a dummy and let the patient make her own material choice based on cost. 88-year-olds and their fixed incomes...yeesh.

Her doctor is notoriously stubborn and has never been one to make things easy for the opticians or his needier patients, unfortunately. I'm sure his line of thinking in this case is something like, "well, her best acuity is 20/40- anyway...just whack her up-side the head with the cyl and get it over with."

[Tallboy]

A plus 3 on the 90 degree meridian should be no problem in CR39, good frame fit, knife edge it. If the cornea is dispersing light, don't disperse it any more tham functionally necessary before it reaches the eye, but before you remake them for poly non adapt make sure the lens doesn't have a ton of stress on it, poly increases unwanted stress dispersion from bad lens edging more than any other material because its so flexible and high index.

Or just do exactly what the doctor wants, and then show you know what you are talking about to cultivate a relationship with them.

[lensmanmd]

Patient is over-plussed. -1.25-2.50 to -1.25-5.00 is not as drastic as +1.25-2.50 to +3.75-5.00. Combined with a 10•shift in the OS, there isn't a material, nor adjustment, in the world that would make her vision comfortable. Time for a second opinion on the RX.

[Kwill212]

IMHO this Rx change is pants-on-head crazy. Do you have her old and new acuity? If her vision is truly blurry and not just distorted, as I suspect it is with that Rx change, there is no amount of adjustments, adaption time, or material changes that will fix it. Have you spoken to the doctor directly? Before I remade lenses bannging my head against a wall, I would request the doctor trial frames/flippers the new and old Rx at their own office to see the patients reaction. I would bet her reaction is the same. Then the Rx can be adjusted accordingly.

As far as the adjustments go, I can't see any way that any of those are going to help this situation.

Poly isn't great, but I doubt it is the main problem here.

[Robert Martellaro]

Haha! Yeah, Quince, give us your $0.02!
I'm not a poly fan, either, but I was a dummy and let the patient make her own material choice based on cost. 88-year-olds and their fixed incomes...yeesh.

Her doctor is notoriously stubborn and has never been one to make things easy for the opticians or his needier patients, unfortunately. I'm sure his line of thinking in this case is something like, "well, her best acuity is 20/40- anyway...just whack her up-side the head with the cyl and get it over with."

Poly won't degrade the on-axis vision in this case, but might reduce the near vision somewhat. The vertical imbalance might also be responsible for asthenopia at near, but shouldn't cause reduced acuity. The two conditions combined could make the near vision unacceptable for some folks.

For the distance vision, it comes down to whether she sees better at 10+ meters with the old eyeglasses than with the new eyeglasses. If true, the Rx needs to be reworked.

Patient is over-plussed. -1.25-2.50 to -1.25-5.00 is not as drastic as +1.25-2.50 to +3.75-5.00. Combined with a 10•shift in the OS, there isn't a material, nor adjustment, in the world that would make her vision comfortable. Time for a second opinion on the RX.

Probably maybe. I would've expected a minus sphere bump in the right eye considering the significant plus cylinder increase. Regardless, if the distance vision is better with the old eyeglasses, the reduced acuity at far is due to the change in Rx.

Hope this helps,

Robert Martellaro

[Tallboy]

All you can do is refit the frame to the doctor's specifications, textbook as you can. Switch from the poly while you are at it. They still won't be able to see and then maybe just maybe the doctor will bring themselves to consider it is their RX mucking things up.

You may gain a new fan in this doctor who will respect you, or a headache. I hate doctors who are never wrong

[optical24/7]

Is this an outside Rx? Do you have a trial frame set? I would trial frame before I made another set of lenses, that way you can easily check if it's an Abbe problem (Doubtful). ( Actually, I would have trial framed it prior to making the original order.) If you can confirm a substantial change from the new Rx, and after the original Dr has already re-checked with no power change, I would recommend the patient get a 2nd Dr's opinion. ( Hopefully one I know and can talk to).

[Quince]

Haha! Yeah, Quince, give us your $0.02!
I'm not a poly fan, either, but I was a dummy and let the patient make her own material choice based on cost. 88-year-olds and their fixed incomes...yeesh.

Her doctor is notoriously stubborn and has never been one to make things easy for the opticians or his needier patients, unfortunately. I'm sure his line of thinking in this case is something like, "well, her best acuity is 20/40- anyway...just whack her up-side the head with the cyl and get it over with."

Lol! Of course the day I'm super busy out front I'm needed to publicly bash poly!

I have to agree with everyone that a more subtle approach to increasing the cyl would be my primary focus. I have a co-worker whose Rx is a plano -2.75 cyl and she won't wear over a -1.50. We've looked at upping her cyl power slowly, but the matter of the fact is, we are looking to achieve 20/happy here.

If money was not issue I would strongly suggest Tribrid for this patient if whatever lab you use offers it. This is a prime Rx for that material but Trivex or 1.6 would appropriate as well for a groove. All of these cost more of course, so if money is inhibiting a better material I would suggest a frame change so the lenses can be switched back to CR39.

Aside from monitoring that OS axis shift, I would also be looking very closely at the fit of the previous pair. Is that where the Dr is getting their fitting suggestions from?

Either way- I'd start with trying to talk the Dr into meeting halfway on the increase and see about a possible frame change to accommodate for CR39.

Good luck!

[McAnerin]

My first step is to match all fittings with the original frame. After that I would swap out of the devil material called Polycarbonate. After that I would try the Rx through a trial lens, and see if the result is different. If they work with the trial lens, find out how far out the axis is on the regular set. Sorry, but that's all I've got. I mostly wanted to post to show off that my signature also hates poly, albeit a bit more cynically.