drawing the line

[edKENdance]

This post might ruffle a few feathers but I am wondering at what power you would definately put someone into a higher index over a poly lens. I'm thinking more in terms of hyperopes but myopes as well. What are some of the variables that lead to your decision ie: px is wearing poly now in a +3.00 but the new rx is for a +4.00 therefore I will use poly again.
Personally at this moment I'm wearing a pair of poly spheres +3 ou no ar because my 2 year old destroyed my regular pair. Yeah, he's the guy in the picture. I am used to spectralite with ar but feel no descernible decrease in visual acuity.
Looking forward to your thoughts.

[chip anderson]

Plano unless its for a child or for safety glasses. Don't use poly at all if I can help it.

Chip

[Diane]

Poly for children...all the time. Poly for safety. As far as other materials, I believe that the best material is what is best for the visual and functional tasks.

It seems like we're getting so hung up on protecting our backsides that sometimes we fail to educate out patients as to what is really BEST for them, and just go with the easiest.

Remember that folks used glass for years, and CR-39 "ain't" so bad either. What with the various levels of high index as well as poly, and the different types of surfacing abilities, we have a "LARGE" toolbox of lenses available to us today.

Discuss lifestyles and determine what the intended use of the eyewear will be and you may find that you will want to go to many different materials for various pairs.... An informed/educated patient/customer is a good thing, when we do the education.

Just my 2 cents worth.

Diane

[bblack]

Poly is a solid lens material and for the price is one of the best values in the business. I am a +6.00 and use spectralite, which I prefer. I have made my lenses in most indexes up to 1.71 and there is very little difference in my thickness over spectralite. The key to a thin plus lens is decentration, AR and aspherical lenses. The impact of decentration effects thickness more than the index of refraction. I would start to consider using the highest indexes lenses on myopia over 4 diopters. I believe poly, spectralite or trivex for everybody else. Glass and CR 39 for the most budget minded consumer. Our patient/customers are like snow flakes they are all a little different. There is no one size fits all in the optical business.

Bill

[Johns]

I wear poly aspherics w/ AR, and they seem as good to me as any high index.

...then again, I'm only a +1.50 hyperope, and I can look through tissue paper just as easily.

[LENNY]

It all depends if it is a stock or surfaced lenses!
Stock Poly comes in plus in 65 or 70-73 mm blanks!
If for your particular job 60 mm blank is just enogh i would order CR-39 in 65 mm blank. The job will come out thinner than stock 65-70 mm Poly. Again if you need smaller than 60 mm blank and rx is not higher than +5.00 I would surface cr-39 (for some reason practicaly they come out as thin as Poly). Also if you need larger diameters the stock aspheric lenses in Poly or Cr-39 depending on the blank size.
In minus it is totaly different story. Higher index= thinner lenses!

In my opinion when working with stock lenses right frame size and shape, the blank size and avialable asphericity will do amaizing things even in regular old CR39!

[Robert Martellaro]

If it's a single vision lens (Rx'd for distance/general use), I will strongly consider a switch from poly to a higher abbe lens around six diopters, or as little as four diopters if there are frequent close tasks, which require a downgaze like reading and desk work. Multifocals force a greater reading depth, and subsequently the near gaze is further off axis than with single vision lenses. I have seen polycarbonate multifocal clients with as little as +3.00 on the distance comment that the J1 line was less distinct, with lower contrast than their previous cr39 lenses. Increase the power and J1 becomes downright blurry, and at some point unreadable. Like you said, it depends on what you are use to and what level of performance is desired. At a minimum, just to CYA, I would warn a client with a moderate power lens that a switch to poly from a higher abbe lens will result in, to varying degrees, a rather "soft" focus at near point.

Robert

[Homer]

I do my own finishing and dislike poly for several reasons other than the Abbe value and related disadvantages. I hate working with it. So I am in Chip's camp on this one.

As Diane said, we often dispense to cover our backsides rather than to offer the best visual quality to our patients. Diane also said (God, she' good), we have a large toolbox to work from. Why use an adjustable wrench when you have a socket the fits exactly?

I use poly when pressured into it by the patient, or doctor and sometimes industrial purposes, otherwise it is CR39, Glass or one of the high index offerings. Isn't it kinda funny that highly skilled, professional opticians still dispense untempered glass lenses with 1.0 centers in most of the world except for the US. It is actually a scheem to cause the rest of the world to go blind so that the US can emerge number one in the new "cold war". (sic)

Anyway, my favorite SV lense for Hyperopes is cosmolit. If you get past +4D I would strongly consider a 1.6. I order my uncuts with a 1.0 edge thickness (if the average thickness allows) and when mounted in a frame with minimual decentration really has an impressive look ---- AR or no AR. My success with spectralite is limited.

[aaron]

I second Homer on the Cosmolite. They come out just great.

As far as the poly debate goes, I currently go between 2 pairs of glasses for myself. The first is a poly transitions w/ ar, the second is a zeiss 1.56 w ar. I must say in all honesty that when both of these pairs of glasses are clean I can see exactly the same through both in all conditions. So I know the specs on poly but don't have a problem dispensing it for any high rx.

For a more direct answer I usually start recommending at least a mid-index or aspheric design as early as +/- 2.00. The patient is always happy with the extra thin appearance.



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[edKENdance]

Thanks for all the responses. I guess what I was originally getting at is that people seem to lose their faith in poly at some point due to abberations in higher powers. I'm thinking of a script along the lines of +8.00 -5.00 x90 in a 54 a. Is this just experience speaking or is it based on any factual evidence that at some point poly just isn't effective?
I'm really wondering at what point dispensers lose their faith in poly for fear of remaking lenses that they would reccommend another lens.

Obviously, I appreciate any comments.

[LENNY]

I think i was loosing my faith in the higher indexes much often than in Poly!

[Homer]

Obviously I have never had much faith in Poly at any time so I don't have much to loose.

Maybe this deserves a new thread but could it be said that the difference between crown glass and CR-39 is almost a great as the Poly / CR-39 debate?

Some patients (and opticians) can wear anything, others can recognize a real difference. While we might be able to suggest some things objectively (ie. Abbe Value) is has not to much to do with how a particular patient will respond.

I look forward to your comments, ya'll.

[edKENdance]

Perhaps I'll expand on this a little. When you dispense a pair of glasses in a higher power as mentioned above and the px has difficulty seeing and everything has been ruled out(bad script, pd, oc height, etc...) Do you deem them as someone who is unable to live their life looking through polycarbonate lenses? What kind of numbers do you have to deal with in terms of remaking glasses by changing the material to a higher or perhaps lower index?

As a sidebar, isn't being human all about being able to adapt?