Trivex

[Darryl Meister]

Post scriptum,

For those OptiBuffs out there who want to play with some chromatic aberration experiments on their own eyes, here is a neat one... The Duochrome test is a good way to see how axial chromatic aberration causes some colors to be in better focus than others. However, if you observe a horizontal object or bar against a bright sky (perhaps across a window), you can experiment with the "color-fringing" of your own eye. While looking at the horizontal object, slowly raise the horizontal edge of a card or piece of paper over one of your pupils (be sure to occlude your other eye). As the card limits the light entering the eye to peripheral zones of the pupil, you will see blue and yellow color-fringing around the object.

Best regards,
Darryl


[This message has been edited by Darryl Meister (edited 04-24-2001).]

[David Wilson]

Great stuff, Darryl,
There's nothing like a discussion on CA and reference wavelengths to put a bit of colour in your life (sorry!). With a distance power of +6.75, though, finding colour fringing is rather easy for me to find (should I choose to), albeit the CA of my specs. But the experiment is great (and I plan to use it with my students).
Regards
David

[Pete Hanlin]

This has been one of the most "intellectual" strings I've seen on OptiBoard. I feel like I'm visiting a chat room at MIT or something! My only question for the esteemed panel is- "What is the index of refraction of most IOL's, and is there any particular chromatic effects on the post surgical eye?"

The duochrome test is one of the most useful tools I've found to determine the appropriateness of a patient's prescription- I use it quite often in troubleshooting. The course I teach on the correction of myopia (which I'll be giving again on Sat., thanks Diane :) ), includes a section on this little test- which seems to garner a lot of interest.

As for mid-index materials, I have to agree with the earlier posting that such materials are basically so much garbage. This new material (trivex) sounds interesting, but at three times the price of poly, I'm guessing poly will continue to become the lens of choice in the coming years (especially as new Opticians without pre-formed prejudices against poly continue to enter the field).

Pete
PS- I assume trivex has UV protection built into the material and accepts tints readily?

[Darryl Meister]

Originally posted by Pete Hanlin:
This has been one of the most "intellectual" strings I've seen on OptiBoard. I feel like I'm visiting a chat room at MIT or something

Hi Pete,

I consider our little "Ophthalmic Optics" forum here to be a kind of optical oasis -- free from ranting, mockery, insult, and prejudice. We talk about lenses, optics, dispensing, and vision here -- and save everything else (the less interesting stuff, in my humble opinion) for the General Forum. All are welcome. ;)

Best regards,
Darryl

PS
I'm not sure off the cuff, but I believe that IOLs use plastic materials similar in optical properties to PMMA and hard resin. Some newer IOLs might use silicone though. In either case, I'm sure the Abbe of these materials is higher than the Abbe of the eye itself.


[This message has been edited by Darryl Meister (edited 04-27-2001).]

[Darryl Meister]

Hi David,

I looked into "The Optics of the Human Eye" by Smith and Atchison. The book you are referring to is a newer text than the book I have from them (which covers optical instruments as well). I'll have to order a copy of their latest work. Thanks.

Best regards,
Darryl

[David Wilson]

Hi Darryl,
The book is good. I had the pleasure of meeting David Atchison two weeks ago. He is a senior lecturer in optometry at the Queensland University of Technology in Brisbane (about 600 miles north of me, here in Sydney}. I was visiting his campus and had a chat with him. He's a nice guy and his knowledge of optics goes without saying. Unfortunately I haven't met George Smith. He is at the University of Melbourne (about 600 miles south of Sydney). Must be hard co-writing a book with 1200 miles between you!
By the way, I liked your comment about this forum being an oasis.
Regards
David

[Susan Henault]

First I'd like to say that all this talk about the abbe value of the human eye is totally fascinating . . . So have you deduced that it is somewhere around 55??

Second - I would like to comment on Bev's assertion that:

"Aspheric lens design reduces or eliminates optical abberations produced off axis. It increases the optical performance of any lens material. It is easy to demonstrate this feature to a patient. Much easier than showing the difference in index of refraction."

While it is true that aspheric design reduces or eliminates off axis aberrations, so do "best form sphere" designs. A well designed aspheric lens provides visual acuity that is every bit as good as the best formed sphere. Because the aspheric design typically coincides with a much flatter base curve, images viewed by the patient are less magnified (or minified) and therefore could be described as "more natural". This improved visual performance, if you can call it that -- is in fact the most difficult feature to demonstrate to a patient.

If you want more detailed information on the ins and outs of aspheric design -- i.e. explanation of 'distortion' an the other aberrations that occur in all lenses, I highly recommend a (very dry but informative) white paper on the subject, written by Steve Machol while he was the Manager of Sola's Technical Services. Happy reading!

[Steve Machol]

Originally posted by Susan Henault
I highly recommend a (very dry but informative) white paper on the subject, written by Steve Machol while he was the Manager of Sola's Technical Services. Happy reading!

I think Darryl Meister of Sola wrote an even more dry and more informative paper on this subject as well. :bbg:

[Darryl Meister]

For the those who truly desire dry and informative, we had some of those articles in the OptiBoard Downloads section. There was also an Excel spreadsheet I wrote, called OpticsLite, that allowed you to experiment with best form and aspheric lens design -- as well as some other opti-nerd kind of stuff.

Best regards,
Darryl

[Pete Hanlin]

Back to Trivex for a moment, I notice in the latest Eyecare Business (May 2001, pg. 18) a quote from Bill Spies, HLOA president, concerning pricing for Hoya's release of a Trivex product (Phoenix):

at a price competitive to comparable products with just some of the features offered with Phoenix Lenses...

Now that we've cleared THAT up... I see big trouble for any mid-index material that costs any more than poly carbonate...

Pete

[CEO]

Great Discussion!

By the way, Younger released Trilogy today 7 16 01.

[Joann Raytar]

Welcome CEO! It is great to have you posting on OptiBoard!

What lens styles is Younger rolling Trilogy out in - SV, PAL?

[CEO]

Trilogy is coming out first in Single Vision Aspherics Base curves:
0.50, 1.25, 2.25, 3.00, 3.50, 4.25, 5.00, 6.00, 7.00

Image Progressive will follow in Oct.

[Laurie]

I think Aspherics are better than best form lens because of the flatter curves, thinner outcomes...

Hi,

Ditto to what Darryl said about the downloads here and his optics lite program. Since he showed me the program a few years ago, I've been incorporating it into my classes, and many vision expo seminars. It is a very user friendly way to illustrate complicated lens theories.

If you haven't played around with the program yet, I would highly recommend doing so.

Laurie

[LO1007]

Just wanted to put my own experience about Phoenix into the mix here............
I got my Phoenix Hoya Wide about 3 weeks ago..........and I have to say they are really fantastic!! My initial reaction was that the clarity was just amazing. The lenses are very clear and no chromatic abberation what so ever. They are also extremely light weight. Everything they told us this lens material would be. Reaction from others that have tried this material and lens design is equally as good.

just so you know my rx is -300 range with a 1.75 add.

[Joann Raytar]

Folks are saying that Pheonix and Trilogy each are both Trivex but they are different from each other. Can anyone explain the differences?

[RT]

Both "Phoenix" and "Trilogy" are based on the PPG material named "Trivex". However, HOYA has added some more chemistry to the mix, and named the result "Phoenix". I'm not sure on the details of exactly what the difference is, but I think one reason for the modification was to make it easier to mold. Trivex is essentially like epoxy--mix the goop up, and it hardens. As such, molding lenses is vastly different using a Trivex based material than other material types. My understanding is that Phoenix solves some issues and allows a greater production yield. HOYA has a history of this type of chemical modification: for example, they use a proprietary modification to CR39 that makes their lenses easier to hard coat.

Based on our tests in the lab, both Trilogy and Phoenix process identically. However, if you place a Trilogy lens and a Phoenix lens side by side, you can clearly see that there is a color difference. The Trilogy lens looks a little cloudy and bluish. That's one reason why HOYA has been careful to use the Phoenix name exclusively when referring to their Trivex based material.

[RT]

There is a good article in the September 2001 edition of Eyecare Business (page 115) on Trivex, Trilogy, and Phoenix. According to that article, HOYA's Phoenix has "better elasticity, thermal qualities, and processing capabilities", as well as fitting HOYA's production process better.

The result of these modifications is a slightly lower Abbe value (43 vs. 46) than Trilogy. However, Phoenix retains all of the base characteristics of Trivex: lightweight, impact resistant, solvent resistant, and good optics.

[karen]

It is my understanding that Phoenix has Hoya's proprietary SRC also. Just got a pair myself in in Silhouette 3 piece to see how it holds up. So far so good. Great VA at night which is tough for me being post RK with an unstable cornea and not correctable to 20/20. I put the HiVision Ar on it and from across the room it looks like I am not even wearing spex!

As per Jim G's request- I am a Hoya Lab employee:bbg:

[Jim G]

Is CEO (David?) around? I'd like to see Younger's response.

Just to be fair, I'd like Hoya employees to ID themselves when writing about their products. Their comments may be valid but, they may also just be the "party-line."

[CEO]

Both Trilogy (Younger) and Phoenix (Hoya) are based on the PPG material Trivex, so this certainly makes both materials close "cousins" to one another.

What really needs to be remembered about Trivex is that it is really a new category of material unlike anything else out there before it.

Basically all plastics have similarities, and typically can be put into two broad classifications: Thermosets and Thermoplastics. Polycarbonate is a thermoplastic, which means it can always be "reformed" by applying heat to it. This "flexibility" gives polycarbonate some of it's great properties such as impact resistance, but also leads to some of it's drawbacks such as being difficult to process to very thin centers, where it may be subjected to high processing "heat".

CR-39 on the other hand, is a thermoset. A thermoset is very similar to a thermoplastic in that it has long molecules as polycarbonate does, but during the curing process "cross links" are formed and this makes the material very stable and easy to process. Once a thermoset is "set", it can never be reformed, even through the application of heat.

Trivex, both Trilogy and Phoenix, is different. They form a whole new classification of material which is a sort of "quasi thermoset/thermoplastic". It takes on the great strength of a thermoplastic, but has the stability and optics of a thermoset.

Really we are in the very early days of this new category of material, just as we were once in the early days of CR-39 and Polycarbonate in the past.

I would be careful to judge either of these materials too quickly, since we are in these early stages. For example, reference above was made to Trilogy lenses which appeared not perfectly clear. Certainly this is not one of Trilogy inherent characteristics, but rather could reflect early samples which were sent to labs as testing, or could be one of the literally thousands of lenses which Younger has been supplying to the labs merely as test samples and may have had some production defects.

It would be missapropriate for me to try to compare Phoenix and Trilogy, since to me both represent different approaches to using the material Trivex. Both succeed in what they are really trying to do, and that is to introduce a whole new category of material to the industry, something that has only happened a only a very few times in our industry's past.

[Joann Raytar]

It may have actually been said already but I believe Trilogy will be the first to come out in a photochromic, is that true?

[sticklert]

I work for a Hoya Lab and we have been told that Phoenix will become available in transition by the first of the year. We will probably hear more in the next month or so.

[sandeepgoodbole]

Originally posted by RT
Clarifications seem to be required here. First, I work for one of them there HOYA labs (gasp), and have had the chance to do some of the testing on Phoenix. "Trivex" is the name of the raw material sold by PPG. "Phoenix" is HOYA's proprietary version of Trivex. "Trilogy" is Younger's name. Since the material hasn't actually shipped yet, it's pretty tough to have formed an opinion so far.

The material is actually nothing like Spectralite, other than having an index of refraction around 1.53 (Spectralite is 1.537). The material processes very similar to polycarbonate, and has the same level of impact resistance, as was demonstrated rather violently at Vision Expo East. Yet chemically speaking, it is nothing like polycarbonate either.

As stated, Trivex/Phoenix/Trilogy has a much higher Abbe value (43-46, depending upon who you listen to) than polycarbonate, thus eliminating the distortion covered ad nauseam in the General Topics. This material also performs better than poly on the ISO Robustness test, chemical resistance (acetone doesn't hurt it), and in tensile strength testing (also demonstrated at V.E.E.). One of its best features is superior drilling capabilities--superior to any other material we've used. As such, it stands out among mid-index materials, which are notoriously prone to cracking when drilled.

It would be wrong, however, to think of Trivex/Phoenix/Trilogy merely as a replacement for polycarbonate. With a higher index of refraction than CR-39, a very low specific gravity (1.11), and a nominal surfaced center thickness of 1.3 mm, Phoenix lenses are about 35% thinner than CR-39, and significantly lighter. The combination of three features (good optics, impact resistance, and lightness) is what the "Tri" nomenclature is all about. With any other material, you can only get 2 out of the 3.

Since Trivex/Phoenix/Trilogy refers to a material, it is neither spheric or aspheric. That would be a property of the lens design. The first lens designs that will hit the market will be HOYA's GP Wide progressive and spherical single vision. Other lens designs, including aspheric SV will follow later, as will a Transitions version.

Stay tuned.

RT

Can you try making frames out of this Tougher an lighter Material?:idea: :idea:

[Bev Heishman]

I noticed that my Trivex samples from Younger and Hoya are markedly different in coloration. The Younger sample has a gray look reminescent of early poly where my Hoya sample reflects more of a water white effect. Comments from CEO?