What is the most easy way of deceiding the amount of prism for a non-strabismic patient?
How many percent of patients in a normal clinic setting would have the need for prisms?
What is the most easy way of deceiding the amount of prism for a non-strabismic patient?
How many percent of patients in a normal clinic setting would have the need for prisms?
Why you be done to be needin any prism in a non-strabismic patient at all, other than convergence compensation?
Chip
it is only for convergence compensation
Chip and others:
Think of deviations of the ocular axes as a continuum: from those who at rest have their eyes perfectly aligned, to those who at rest who have their eyes obviously deviated.
There is some middle ground where the eyes do deviate at rest, but with effort (autonomic "fusional vergence") they will align. This is called a phoria.
Imagine the potential for eye strain when your muscles are tensed partially in order to keep from seeing double (or suppressing the vision in one eye).
Duane-White classified the basic horizontal deviations:
Basic Exophoria
Basic Esophoria
Convergence Insufficiency
Convergence Excess
Divergence Insufficiency
Divergence Excess
Contrary to above posts, prism is least likely to be prescribed for convergence issues.
Vertical deviations are far more complex, and almost always get prism.
As to prescribing prism, suffice it to say that there is no "simple" answer, and it would involve much understanding.
having worn prism myself for 30 years, both vertically and horizontally, and working in the business for over 30 years, my answer, at first blush would be that it depends on the refractionist. Most of you probably have seen it yourself through the years, there are docs that prescribe prism for 50% of their patients, and others where you never get an rx from them with prism requested. To me it seems very subjectve, and being that the eyes can accomdate for about 2 degrees of prism without correction needed, and the fact that people like myself who are exophoric with convergence insufficiency "eat up" the prism that is given them, most docs are pretty conservative with prism rx's.
Many people use the fixation disparity measurement or associated phoria to prescribe prism. In this approach, the prism prescribed is only about 1-3 diopters
Remember: Ophthamic prism is measured in diopters, not degrees. Astrologic prism is in degrees. And I have had ophthalmolgist tell me how many (in mutiples of 10) diopters of prism they had personally and didn't include in thier personal spectacle Rx.
chip
Do ophthalmologists even know how to measure muscle deviation?
Originally Posted by drk
It depends upon the office. Two OMD's I worked for vary rarely prescribed prism because the techs did not know what it was and how to search for it. Now OD's on the other hand were quite skilled at this. That's why I have always said if you want a good refraction see an OD if it's surgery see OMD.
just my 2 cents :bbg:
You can use Sheards and Percivals Rules to decide how much prism to Rx for esos and exos. I thought about using it the other day, but wussed out and went with 1 pd BI OD,OS for a CI patient.
oh yeah, it was a combination of wussing out and the fact that she completely suppressed on BI and BO vergence testing.
I truly hope that's an exaggeration.
I have to admit, the particular doc in question that dolled out 50% prisms on his RX'S was 30 years ago, actually the first one to prescribe prism for me. My point is still the same, though, that I have been in a position to see many different docs RX'S, both OD'S and MD'S, and as a rule the OD'S prescribe much more prism than the MD'S. Also, there are those OD'S that prescribe a much higher percentage of prisms than the others. I am sure it isn't because they have a much higher percentage of exo and eso patients.
Simple:
Same reason O.D.'s Rx more bifocals on children. Suspect they Rx more planos and +.50-.50's also. They have traditionally dispensed. More money for prism, more money for bifocals on kids, More money in prescribing something rather than nothing.
Chip
Chip, you're either so full of crap or you are stuck in a time warp, or both.
You want to put one of your OMD buddies on line here with me and we'll talk a little binocular vision? I've already shown that you know next to nothing.
We'll also see who's made more money off their patients.
Man, I don't disparage opticans, but you can't resist...impugn not only my profession's expertise but our ethics as well.
You sir, are no gentleman.
I once worked for an OMD who employed several OD's. At the office I worked at the usual course of action was to neutralize the glasses before the OD saw the patient. Now the OD did not notice I had done the neut and went ahead and saw the patient and gave her a new rx. Not much different than old but enough. I then noticed he didn't mark any prism and I just pulled him off to the side and asked where was the prism and he said I didn't notice anything perceptually or see your neut I assumed she had no prism. He called her back in rechecked for prism found exactly what I found 1 out ou and 2 up and 2 dn.
He called me over and thanked me for telling him about the prism. I said no problem DOC thats why we work together he just smiled and walked away.
True story.
Out techs bring me the glasses when the auto lensometer goes crazy and ask me and my old reliable B&L to check for prism. Iv'e done this a long time so I'm pretty good with reading prism, The Four Ophthalmologist I work for are really good at Prescribing the prism, If never prescribed before and needed. But the techs and I work together to make sure if there was prism prescribed before by another Dr. we will find it. Theres also the telephone, if the Pt.remembers the last Dr,s name.
It's important for those neutralizing glasses to be careful about not over-looking the prism. If patients are use to it, I'll put it in their new Rx, even if I would not prescribe it myself, based soley on my findings...remember refraction is as much art as science.
And Chip.....I never prescribe glasses to those who would not benefit for my personal financial gain. You are a bitter man....:finger:
I once worked for an OMD who employed several OD's. At the office I worked at the usual course of action was to neutralize the glasses before the OD saw the patient. Now the OD did not notice I had done the neut and went ahead and saw the patient and gave her a new rx. Not much different than old but enough. I then noticed he didn't mark any prism and I just pulled him off to the side and asked where was the prism and he said I didn't notice anything perceptually or see your neut I assumed she had no prism. He called her back in rechecked for prism found exactly what I found 1 out ou and 2 up and 2 dn.
He called me over and thanked me for telling him about the prism. I said no problem DOC thats why we work together he just smiled and walked away.
True story.
True story: those ODs were hired to do ophthalmology, not optometry. They were junior ophthalmologists, "JO", and not "OD".
And your point being what ?
I'm just being an a$$.
Seriously, binocular vision is a type of sub-specialty. Most ODs know nothing about it, and virtually all OMDs know nothing about it.
The type of OD who would self-select to work in ophthalmology would not be interested or trained in binocular vision, by and large. However they would still feel like BV is something they should know, because they had some exposure to it, and would be embarassed to admit that they don't.
I'm kind of prejudiced and old school (God help me not to turn out like Chip), so I don't think they were "real ODs", ergo my put down in the above posts stand.
you have made my point better than I did DRK. My point was that as a rule OD'S prescribe more prism for patients than OMD'S do, those, as you so succintly put it, believe in BV, and comfortable with it.
Wish you folks bad mouthing OMD's had ever met a pediatric ophthalmologist. Then you would really know who is the master at strabismus, prism, muscle surgery, convergence, phorias, etc.
Of course, the orthoptist trained at John's Hopkins are as sharp as can be on this.
Chip
Then maybe your daddy can come on this board and character assasinate optometry. You, however, have no leg to stand on in this issue.
Chip, I totally agree!!!
Unnecessary expensive, time-consuming vision therapy, anyone?
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