Has anyone experienced customer that needs prisma only for neear vision.
Now he uses 2 glasses (1 for far and 1 for near with 5 prisma on each side) and he wants to use progressive lenses.
Is it possible?
Has anyone experienced customer that needs prisma only for neear vision.
Now he uses 2 glasses (1 for far and 1 for near with 5 prisma on each side) and he wants to use progressive lenses.
Is it possible?
What is the prism direction, .....base in?
Both bases are In (nose side).
What is the Rx?
R: +2,75 cyl: -0,25 45° add: 3,00
L: +2,50 cyl: -0,50 135° add; 3,00
You ain't been readin all dem postins bout Franklin Bifocals?
Chip
But a franklin might be kinda ugly as a progressive, don'tcha think?
Here's something you might try: order a pair of older style multifocals, like Adaptar, Sola XL?VIP, and have the lab grind the axis on the right at 15, the left at 165. Ask for 1 d of prism to be ground base out ou..........
Cut the lenses to the correct axis, but layout decenter the lenses to a near(go by near check circle) of 10 mm inset for each eye. You might have to tweak this configuration slightly, but you should end up with a close result.
I used to have the lab modify the 180 line to change the inset (to zero), but I don't see how you get 5^ base in OU at near only. You could get about 3^ by decentering a ft45, but your're still two prism diopters short.
I believe there are only four ways to do this: use a Fresnel prism on one lens cut at the lower limbus, a Franklin, prism segs, or an auxillary pair of readers (use cr39 or maybe Trivex to minimize dispersion for the last two soultions). I recommend the two pairs route.
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.
is the pt asking for progressives, under the impression that his glasses will not have lines?
We convinced to the user to use 2 glasses: 1 for near, 1 for far and he ordered another one for intermediary (about 3 meters). Thank you for all.
I have revived this thread because my boss asked me the other day if it was possible to put horizontal prism in distance only. i called our local lab and asked if this was ever going to be possible and he said there was work being done on this that should allow this to be digitally ground in the near future. Does anyone else know any more?
The Kodak Unique is the only Progressive that allows you to apply a specifc prism for the reading only. Power range is limited though, I believe 2D. Failing that you can decenter the seg to induce prism near only.
I don't recommend an Executive, as they are inherntly difficult even without prism. Impossible with.
Its theortically possible with the Kodak Unique today, but I have not done it myself. With the Unique you would order distance prism, but order the opposite prism for the reading, thus offsetting each other.Originally Posted by rdcoach5
Anyone who needs this much prism (probably anyone who needs more than a total of 3 diopters) ain't gonna be happy with a progressive even if the prism is equal top and bottom. Why do we keep thinking that newer technology is going to be the best answer for every problem.
Trust me you can get enough money for a Franklin without it also being a progressive. And with the above job being anything other than two separate pair of glasses it's gonna be ugly anyway. Isn't gonna be that pretty with prism of a significant amount in single vision lenses.
Chip
I tottaly agree with Chip.
I have fit many Progressives with high amounts of prism sucessfully. If the prism is prescribed correctly there is usually no issue. The problems often stem from Drs who don't take the time to trial frame their patients and give them a chance to adapt to that power. Successfully perscribing prism is a mix of art a patience.
If the patient was in prism previously there is usually no issue. The hard cases are the first time prism wearers. I have in many cases of non-adapts fit these patients in "training" ST-28 lenses for a few weeks to that they adapt to the power before they adapt to the lens. I think the "training" lenses solved those few non-adapts about 90% of the time.
Today, a magnetic layer with the desired prism is an option.
B
That is a great idea!
I am, of course, with Chip on this. A Franklin is the only sensible way to go. The problem with using any segmented bifocal or progressive for this is that you effectively narrow the read area, progressives don't have enough anyway. I believe Barry was talking about using a clip on for this, nice idea but ugly and at times impractical. I don't know if there really is a good answer to this, maybe just what the patient is most comfortable with.
Last edited by Jacqui; 12-16-2011 at 09:22 AM.
such an add is a guaranteed non adapt anyhow...................................
How come the old opticians still come up with the best solution in such a modern age of technology when it comes to difficult cases. How come nobody mentiones that a PAL with a +3.00 add has not much reading area. A first time PAL wearer with such an add is a guaranteed non adapt anyhow.
I have always found the Franklin to optically horrible. There is often tons of unwanted prism, the segs are never centered correctly inducing unwanted prism in the near, the distance OC is often not centered correct , not to mention the enormous thickness and weight of the lens since its only available in CR-39. I just had 3 remakes on one pair because it was simply not passing ANSI standards. There may have been a time when Franklins could have been made with precision and skill but most of those skilled opticians have retired.
Since I have started in 1994 in Optical I have had more Franklins fail final inspection than any other lens. This patient needs more precision than a Franlkin can provide in my opinion.
Franklin Seg is what we used...Ain't pretty but the patient didn't mind the look and she loved the vision. Follow-ups with her confirm that all is still going well.
-Chris
You ain't makin' them right. I never have any of the above problems. Been makin' them for about 42 years. I do offer training courses at your location (ain't free).
We don't make them, and probably never will... out source only, the time required is not worth the few a month we process. There should be seperate certification for Franklins, its an art form. I hope someone in your lab has the ability to carry on your skills so the art form isn't lost.
If I ever get smart enough to post pictures and video's on OB, I have a video and stills on how to make a Franklin, almost any Optician do it. Takes some time (an hour or two, not months), No unwanted prism, etc. The beauty of them is you can put the prism and center hights anywhere you want them to be.
Cost? Exactly what the cost of two pairs of SV lenses would be if you don't screw up + your time. You don't even have to have your own edger.
Chip
Last edited by chip anderson; 12-22-2011 at 01:08 PM. Reason: Wasn't finished.
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