Definity Fourth Zone for larger frames

[rinselberg]

Definity Fourth Zone for larger frames

When the PAL segment height is equal to or greater than 23mm, Definity adds a (fourth) intermediate vision zone below the near zone. According to Definity, the patient experiences better vision when looking downwards (as one may do when walking on stairs or rocky ground) and "minimizes distortion and flattens the visual field". That second part is Greek to me: I am not an ECP. Since it does not say otherwise, I assume that this additional zone is provided automatically on all orders that specify >= 23mm of seg hgt and cannot be de-selected (?)

What are the patients and ECPs saying about this? Is it better than having the near zone go all the way to the bottom of the lens? Does the 4th Zone make the bottom edge of the lens remarkably thinner than it would be otherwise? Is it common to dispense PALs with >= 23mm of seg hgt? Could anyone verify that part about "minimizes distortion and flattens the visual field" and put it in a way that would perhaps be more understandable to a layman?

[rinselberg]

Definity Fourth Zone for larger frames

You may click on the hyperlink above to see a diagram of the Fourth Zone and access the Definity website.

[rinselberg]

I lifted a more educated explanation of the theory behind the innovative Fourth Zone from Vision Care Products Online:

In larger frames where the segment height is 23 mm or greater, Definity provides an innovative Fourth Zone, below the reading zone, for better vision when glancing downwards through the bottom of the lens (walking on stairways or on rocky ground ...). With other progressive lenses, the power of the prescription is still strong at the bottom of the lens because of the add, which can create distortion and cause straight lines to look curved: The stronger the add, the greater the distortion. In the Definity Fourth Zone the power gradually decreases to reduce distortion and allow straight lines to appear more natural.

I welcome any comments from Definity retailers or users of this lens.

I am considering my first time ever progressive lens. I think that my frame preferences may put me into a segment height of 23 mm or greater, where Definity departs from other PALs by adding this Fourth Zone at the bottom of the lens. Until recently I have been so negligent in keeping my Rx up to date that I really have no idea about my Rx, whether it is relatively moderate or strong, except that I am certain that I am presbyopic. Therefore, I really should not make too many more possibly stupid posts until I actually have my Rx determined! I am not trying to promote any particular lens product. But I do admit, I could hardly wait to make another post after I came up with my new OptiBoard User SIGNATURE.

[Rich]

Hi:

We've been fitting Definitys for amost 1 year now and I can tell you that it is one of the superior lenses on the market. Same applies to Zeiss individual which we also use, though not as often because of price & material limitations.

You seem very concerned with the "fourth Zone" which for 90% of our fits just doesn't apply. We rarely fit larger frames now so over 22 or 23 mm is unusual. That said, the fourth zone can only be a plus. It really does not reduce the reading area noticeably, because it would usually be awkward to read 23mm down. It really is in the extreme lower periphery of the field of vision.

If you're considering this lens for yourself... try it, you'll like it. Though I easliy adjust to Comfort, Gradal Top, Summit, I keep going back to my Definity's lately.

Hope this helps.

Rich

[Ryan]

I do agree with the last post. We really don't fit patient's with above a 23 seg height, so the 4th zone doesn't apply most of the time. But I do think it is a good idea simply because if the seg height is higer than 24, then the very bottom of the frame isn't being use for reading, the frame comes down too far. So I think unless you go with a large frame, then the 4th zone shouldn't be a big factor when purchasing a lens. I do think the Definity is the best lens available,(based on fitting my patients) compared to others. I still love the Varilux Panamic as well, but the patients compare the difference in Definity and whatever else they had, and it is no comparison, so far 99.9% of the time.

[Pete Hanlin]

To speak directly to the question you raise (re: the "innovative" fourth zone), it amounts to this- below 23mm the ADD power backs off a bit. Although J&J claims this is a "unique" feature (which would seem to imply they are the only ones who do this), there are other PAL designs with this characteristic.

As previously noted, however, very few fits today have a height of over 23mm- so the "fourth zone" amounts to something akin to a "Twilight Zone" (i.e., its interesting to talk about- but very few people actually go there). Additionally, while backing off the ADD power a bit below 23mm may thin the lens a bit (which is actually the primary reason this is done), it does not overcome the aberrations inherent to a point in the lens that far from the optical center anyway.

If the marketing really has you convinced that the Definity design is just what you need, I would suggest you ask your eye care practitioner for a Sola XL Gold. This design has several features which are similar to Definity's soft corridor design- at a much more reasonable cost. Additionally, it is available from a lab that your ECP has an ongoing relationship with.

[Robert Martellaro]

Paraphrasing Pete's comments it's simply marketing hype. Definity's claim to fame is the atoric design. Otherwise it's no better than other lenses, and in my book it may not even be the equal of some other designs. If your cylinder power is >.75 the Definity lens and other atoric PALs (along with some non-atoric designs) should be on the table.

The best lens for you will depend on the Rx, how you use your eyes, and your visual and cosmetic priorities. A good optician will help you sort this all out, and will make a recommendation based on the above. The best optician will be older and presbyopic, and will have worn all of the lenses that are being considered for your glasses.

Robert

[mrba]

The best optician will be older and presbyopic, and will have worn all of the lenses that are being considered for your glasses.

Fascinating.

[Jacqui]

That sounds like me

[rinselberg]

Regrets JACQUI, but if Wi. stands for Wisconsin, you are just a little outside of my bailiwick.

ALL INPUTS to date are very much appreciated.