My dr wants to put 16 base in prism in my patients glasses on the bifocal segment only. What do I need to do?
My dr wants to put 16 base in prism in my patients glasses on the bifocal segment only. What do I need to do?
Franklin bifocal. Double check, that seems like a Gawd Awful amount. How much is on the distance??
Test 1st with a fresnel.
Relax and have a homebrew!
Something seems wrong to me.Originally Posted by optical24/7
Od -0.50+0.50 45
os -0.25 +0.50 135
+3.00 add
pt is aprrox. 88 yrs old.
Wearing trif.
Have script double checked, I think there is something wrong.
Rx prism is for near only? Separate set of reading glasses would be best, IMO
Last edited by uncut; 08-27-2010 at 11:27 AM. Reason: ...
Seems like a lot to me also, hence, test 1st with a relatively inexpensive fresnel.
Yeah, the fresnels come up to 20D, and you just align it, cut it for the bottom of the frame and mount it even with the top of the seg. If it doesn't work, you're only out the cost of the fresnels, which will be waaaaaaaay less than a set of lenses with 16BI OU. Not to mention that you will actually be able to fit them into a frame.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
Dragon, they make up to a 40D (fresnel). Great for trial/final treatment of hemianopia.
Durn it - I knew that. I used a PAIR of the 40d for my next door neighbor when he had a brain aneurism that killed one of his eye muscles.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
Isn't it possible the OP meant 16d base in total prism, which is 8d in OD, and OS respectively?
Just so you guys can hear, what is the total convergence necessary for your average set of eyes @ 33 cm? (+3.00 add).
pd (cm) / distance (M) = ~6.0/0.33 = 18^
With 16^, it means this 88 y.o. lady is being set up to stare straight ahead with no convergence at all to read.
What's more, there is no distance prism requested, so you have to assume that there is no serious neuro-muscular issue. This has to be a convergence issue.
What entity creates no convergence at all? Not many. http://en.wikipedia.org/wiki/M%C3%B6bius_sign
for hyperthyroid cases, but you'd notice her eyes bulging out quite a bit, I'd think.
I think the ophthalmologist probably is incorrectly treating what all absolute presbyopes have: that is, an "acquired" exophoria when their accommodation disappears. But you can't question.
I'd consider making half-eye SVNO's with that Rx...like low-vision reading glasses. Heaven knows the distance Rx is negligible.
If this patient has a convergence insufficiency (C/I) of more than 20 PD, and isn't diplopic, then the patient is likely to be suppressing. If the patient is diplopic, then there is a chance of exotropia of recent onset. if the exotropia is of recent onset then one must suspect a cerebral vascular accident (CVA) or a cerebral aneurysms in one of the neural sinuses.
In either case, I woudn't grind it but would try the Fresnels as somebody else suggested. I'd clarify again with the original prescriber as to intent.
Yes, NP, but no prism in the distance Rx leads me to believe it's not acquired exodeviation.
and furthmore...is this a consumer?...and furthermore, 16 prism diopters in each eye, even ground in, is going to degrade VA so substantially that I can't see how this could ameliorate anything...and furthermore, in fresnel, there would be no quality to VA.
I can't imagine why you wouldn't try this first; it is far and away your cheapest way to test the accuracy of the prescribed prism.
-Tony
Had to double-check the posting date. Welcome back - missed ya!
-Tony
Instead of just testing with a fresnel, you might consider the lenses with the fresnel the final product. I realize the fresnels aren't beautiful, but the lenses will be far less expensive and much thinner (std. lens plus 1 mm for the fresnel) than a set of Franklin bifocal with 16 D of prism. Also, if the prism amount has to be modified, it's just a matter of buying and applying a new fresnel.
Fezz always makes optics seem simple. I'll drink to that!
Maybe the patient has an "A" pattern EXO deviation...therefore distance is less or compensated with head postion (chin down), but patient needs base in prism for inferior gaze through the add.
Just a simple observation, an 88 y/o with such minor distance Rx?! Could this possibly be a problem with Cat surgery gone wrong?
$0.02
I'm not an OD but I can attest to this from an Opticians standpoint. Our OD's and MD's routinely prescribe fresnel/prism. At one point we stocked them as high as 10D - 12D. However because of the low success rate (basically 0%) we now maintain our stock at 6D and lower. What was happening was we'd apply the prism in those high amounts and immediately have to remove them only to have them lower the amounts to about 12D OU or less. Every once in a while we have to special order a higher fresnell but mostly we've strayed away from it. I'd say 16D isn't completely out of the ordinary but you'd almost certainly want to split that, especially if your using temporary prism.
"Wise men don't need advice. Fools won't take it." - Benjamin Franklin.
OHPNTZ, nice catch.
If so, though, SVNO.
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