When a person has strabismus, the pd procedure is:
Occlude one eye.
Take monocular pd on other eye.
Occlude next eye.
Take monocular pd on other eye.
~~~
I'm troubleshooting. I have a patient with strabismus who was not occluded when her pd was taken. When I took her pd (using the method above), her pd added up to the same number but was off by 1mm on both sides.
PS She can't see out of the glasses we made for her using the non-occluded pd.
SV or Multifocal? Prescribed prism? Client history- Rx, client age, etc. 1mm off shouldn't be a problem unless the lens design is progressive, there's Rx prism, frame wasn't pre-adjusted, etc.Originally Posted by pseudonym
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
People with strabismus have usually no binocular vision and need only a balance lens on one eye. So there is no big problem with the PD.
No prescribed prism, client is elderly, slightly hyperopic, it IS a progressive (Solaone), frame was both preadjusted and postadjusted. I postadjusted the heck out of it trying to get the reading area down lower. She can see to read but the distance is no good in the eye that turns outward, which strikes me as weird. I would have expected problems in the reading area.
She demonstrated with her old glasses with one eye covered that she can see in the distance with the turned out eye much better than with the new ones we made.
Am I right in thinking that you always alternately occlude where strabismus is an issue? 1mm doesn't seem like much but it's 1mm in with the eye that turns out and 1 out on the other. She doesn't have a problem with the normal eye.
That is what the person who took the non-occluded pd said. Why can she see in the distance with her old glasses and not with the new? Near vision is good, both eyes. She's not trying to pull a refund scam or anything like that- she was quite excited about getting her new glasses, then became emotional when she couldn't see out of them.
I have a few questions, pseudonym.......Any change in lens power? What was the prism thinning/brand of previous multifocal?
Add one more directive(procedure) to your list on your original post:
Always record IPD of previous eyewear.
A big "I dunno" to any previous info. We merely fill the Rx they bring in and very often do not have any previous history.I have a few questions, pseudonym.......Any change in lens power? What was the prism thinning/brand of previous multifocal?
Add one more directive(procedure) to your list on your original post:
Always record IPD of previous eyewear.
Good suggestion. I definitley should have checked the pd on her previous eyewear, but I missed doing that. The person who, yes, failed to occlude her eye during the measurement seemed intent on getting her back to her doc for a recheck. This will happen at 9:30 today and I expect she will come to us directly after. I'm the only one working today and will have to come up with a solution.
Let's call it +1.00 Add +2.50.
I need specifics. Don't be shy.
Yes. But I always check the measured position with the frame in place (bisect the corneal reflection).Am I right in thinking that you always alternately occlude where strabismus is an issue?
The issue here is probably related to PAL design and Rx.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
Yes, occlude the other eye while measuring PD on a strabismic client.
(see chapter 3, 'System for Ophthalmic Dispensing' by Brooks and Borish).
: )
Laurie
Ophthalmic Optician, Society to Advance Opticianry
I know I am sounding like an antiquated old foggy here with a one trick pony.
But it has been my experience that patients with compromised vision (including adult strabismus, macular degenration, and a lot of other similar conditions) get much better results with any non-Pal type bifocal or trifocal.
I do a lot of this type work as I have a good friend who specializes in adult and pediatric strabismus and we been at it a long time. Pals require a lot of muscle, mental and visual skills from the patient as they are themselves a compromise.
You can't get 20/20 vision from a 20/100 brain.
Chip
Let me throw a wrench in the theory here. I am Exothophic in my O.D. I wear 3 diopters base in prism o.u. and combining 2.50 base dwon o.d. and 2.50 base up o.s. I wear progressives and always had a mono split P.D. of 34.5 o.U. This past two pairs of glasses another optician co-worker suggested an occluded mono P.D. We measured O.D. 36.5 and O.S. 32.5, Yes the lab loves me, Lol but you know, Its works great, I read with both eyes, not just one like before. I have always worn progressives and the Dr. thinks its what keeps the eye in check, from worsening. I won"t have surgery until the procedure changes. Haveing muscle surgery on my o.d. as a child in 1964 almost killed me, and being evaluated 2 years ago theres no garrentee surgery's going to work. I love my P.D., for me it works. So I say try it on your Pt., see if it makes a diference for her. Just my experience as an exothoph.
Wrong. Strabismus does not equal a blind eye. I am intermittently strabismic and would not appreciate having a balance lens. My mother is a constant strab and ans most certainly wouldn't like to wear a balance lens.
We may not using both eyes all the time at the same time, but we have functional vision in both eyes that needs to be corrected. If anything, PD is more important in these cases as you would want to limited any unwanted prism that may worsen the frequency of a strabismus.
No, you don't. An antiquated old foggy- (not you, another one) convinced me to get a FT-28 because I was having problems focusing at near while doing repairs. I made them with computer in the distance part and reading in the segment. I love the vision I get so much that I sell them to people who need to see at computer range along with reading. I've had a lot of happy customers from that "trick" and made a bunch of second pair sales. I've had a plenty of progressives return but not one bifocal has come back with the "can't see" complaint.I know I am sounding like an antiquated old foggy here with a one trick pony.
Chip
Now for the final verdict. I'm eating a crow pie right now. The doc changed her Rx this morning and it was a significant change. Added 1D distance in the right eye and 1.5 D distance in the left.
She didn't mention that she is diabetic and has had two strokes complicating her vision picture.
We're remaking with the occluded pd. Today I did check her old glasses that she can see out of and the pd is 2mm larger on the right and 2.5mm larger on the right than the occluded reading! Wrong, wrong, wrong, but she can see out of them.
This is a strange business. Sometimes the pieces of the puzzle don't seem to add up the way they should.
Wrong. Strabismus does not equal a blind eye.........................................
The study and treatment of defects in binocular vision resulting from defects in the optic musculature or of faulty visual habits. It involves a technique of eye exercises designed to correct the visual axes of eyes not properly coordinated for binocular vision.
Also Known As: Orthoptics and Pleoptics
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition.
Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.
Also Known As: Lazy Eye; Suppression Amblyopia; Anisometropic Amblyopia; Amblyopia, Developmental; Amblyopia
Also see the: American Orthoptic Journal
:poop:
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