With a wrap frame on a 8 base curve for a -3.00 power what distortion if any would one expect? Will the depth of vision be effected? Will objects be as clear as a 4 base curve? Will the custumer still have 20/20 corrected vision?
With a wrap frame on a 8 base curve for a -3.00 power what distortion if any would one expect? Will the depth of vision be effected? Will objects be as clear as a 4 base curve? Will the custumer still have 20/20 corrected vision?
With a higer base curve than whats recommended the wearer will notice and increase of off axis aberrations with marginal astigmatism being of the biggest concern. Wrap compensation that will correct (as much as can be expected) for tit, wrap and vertex distance. Once you have compensated for this and you decide to use an 8 base you will then be left with considerable thickness not to mention that standard edgers have a tough time matching these curves. For this a multi axis edger should be used. This is what ICE-TECH does.
Unfortunately, prescription compensation for wrapped lenses will not minimize the peripheral astigmatism associated with the use of non-standard Base curves. This is a common misunderstanding. Prescription compensation will only eliminate the prescription changes produced by lens tilt at the straight-ahead angle of gaze. Oblique astigmatism will still be introduced away from this position.
Darryl J. Meister, ABOM
Thanks for the quick reply. Would you explain what you wrote above? In a way that a consumer would understand. Is astigmatism the cylinder reading? +0.50 is not much astigmatisim. The eye is like a football... so if it were pushed on edge vision clarity would improve.
What is important here is that the final vision with the wrap 8 base curve is not 20/20. Objects near are clear and objects far are blurry. The clarity is not effected by scanning from edge to the other edge of the lens. So the lens provides a constant image with no distortion but the power is not strong enough. Could this be a result of the prescription compensation?
Is the prescription higher then what is recomended for a 8 base curve?
Here are the readings
Eye | Sphere | Cylinder | Axis
Right | -3.50 | +0.50 | 120
Left | -4.00 | +0.50 | 035
What is tit, wrap and vertex distance?
Why do standard edgers have a tough time matching these curves? How would this effect the product?
What is a multi axis edger?
What is the prescription compensation for 8 base curves? How if any does this effect 20/20 vision with a 8 base curve wrap.
Last edited by rayban; 10-13-2006 at 02:31 AM.
I have the feel of another consumer asking questions.
I've highlighted in bold some parts of your post that make me question:
You list your occupation as ophthalmic tech however ...
1) why would you want an explanation that consumer would understand (unless you are a consumer?)
2) you are asking about astigmatism being the cylinder reading ... an ophthalmic tech would know this - I would hope so ...
3) "the eye is like a football" This is exactly the verbage the Dr's use to describe what astigmatism is to the patients .... a person truly in the business wouldn't need to explain this to the members of the optical field ...
4) when "we" (in the business) write an Rx out, "we" don't need to label the components of a basic Rx (Eye, Sphere Cylindrical, Axis) - "we" know without having it written out like that - "we" don't need line separating the numbers, either ... if "we" use a label for right and left, "we" use the Latin abbreviations...
5) Tilt, wrap and vertex distance are measurements that optical professionals know and use ... consumers don't know much about these things and while an ophthalmic tech MAY not know much about tilt or wrap, I'm sure they would know a thing or two about vertex distance
Adding all these things up, I suspect Chris indeed is correct and that you are consumer (I'm guessing, an engineer ) who is having a bad experience with a pair of wrapped glasses ...
And don't forget my favorite...induced prism!
But, Darryl, cannot we use "digital surfacing with special top-secret back surface design" to offset the oblique astigmatism by going off corrected curve?
I think the "tech" messed up when he chose his sunglasses for his online name! :)
Yes, there are several options available to improve off-center performance using both semi-finished and free-form lens designs. But if Rayban is indeed a consumer, this is a conversation he should have with his eyecare professional.But, Darryl, cannot we use "digital surfacing with special top-secret back surface design" to offset the oblique astigmatism by going off corrected curve?
Darryl J. Meister, ABOM
I have highlighted in bold some of the parts that make me think you were a detective in your past life.Originally Posted by GOS_Queen
1) Your skills of deduction are fabulous. :D
2) Your attention to detail is marvelous. :D
I really enjoyed that, the person did give off a hint of consumer, but after your post I would have a hard time argueing that they are not a consumer.
1st* HTML5 Tracer Software
1st Mac Compatible Tracer Software
1st Linux Compatible Tracer Software
*Dave at OptiVision has a web based tracer integration package that's awesome.
FYI, rayban lied when he registered and has been actively trying to carry off this deception. He is not an eyecare professional.
Thread closed.
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