Can anyone here shed some light on which PAL might give an Amblyopic patient a fighting chance to enjoy a PAL. I have found in the past, that an individual with vision in one eye is often frustrated with the results.
I am wondering if out new crop of PAL's like a Hoya ID or similar beast might help and give an increased visual field in the near and intermediate zones.
Your suggestions will be greatly appreciated.
My thoughts:
If you want assured maximized optics, go individualized, if the patient can afford it.
I believe it to be true that back surface progressive curves maximize field of view, FWIW.
I'd guess some individualized designs weight near and intermediate zone size higher than distance, but I'm not sure which ones.
I think the frame selection would be important.
I'm intrigued with the Sola HDV which "morphs" the design to the frame size it gets to work with.
The other issue is what the state of binocularity is at near...if the patient is a heterotrope, very likely convergence is not occuring at near, making a design that more greatly insets the near zone less desirable. But who knows what insets are used? I've heard essilor does more and Zeiss does less, FWIW.
I have had great success in fitting Amblyopic patients with some of the more current progressives.
As Dr.K stated, I think part of it has to do with the binocular function, and the rx to start. Patients seem the happiest with an individualized lens, however I currently have a patient that is happy with a physio with an rx around +5 with over 2 cyl and about a total of 15 diopters of compounded prism.
(he refuses a lined trifocal. Said he tried them in the past and hated it.)
"Some believe in destiny, and some believe in fate. But I believe that happiness is something we create."-Something More by Sugarland
I've noticed myself that amblyopes do seem to have more trouble with VFLs than binocular people. Having two eyes open and working simultaneously looking through the channels allows for when one eye is slightly off the channel when the head may be turned or tilted...or if a wide object happens to be a little to the left or right of center. In binocular people, if one eye happens to be off, the other one may be closer. Amblyopes don't have this luxury. I've observed this phenomenon on myself (which does not necessarily make it scientific fact).Originally Posted by Gary N. Snyder
I would guess any VFL which has a wide channel would be best. I have had a good deal of success with the digital back surface progressives.
I would add that first and foremost we need to get the fitting cross exactly at the pupil center, using a frame that keeps the vertex distance as short as possible. I would emphasize that separate glasses for intermediate and near may be required if there are frequent close tasks. This would also allow the use of a PAL in the general purpose glasses to have a design bias towards excellent distance vision. Use PALs that have flatter, aspheric curves to decrease magnification. I do not believe we will see increased fields with the more advanced lens designs, unless a custom inset is required (Hoya ID and Zeiss Individual for example), or if the Rx has a very high cyl or sph power.
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.
What are the "benfits" this patient is supposed to derive from progressives?
Chip
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