# Optical Forums > General Optics and Eyecare Discussion Forum >  Trouble with New Trivex Lenses

## bev

Hi, I'm new to the site and just wondered if anyone got the new Trivex lenses but preferred the old polycarbs better. I also got AR coating on the new pair but the old pair still seems better.  I know the new Trivex are supposed to have better optics but my old pair seems sharper to me.  I have single vision with one eye being -2.0 and the other eye is now -4.0.  The old pair from two years ago has -2.0 and -3.75 so not that much change.  Any feedback would help as I have less than 30 days now to return if not happy.

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## drk

It's difficult to understand why you don't see at least as well with the trivex.  If you move your head up and down, do you find a clearer spot in your lenses, other than what you normally are looking through?

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## bev

Well, I can see things differently with the Trivex but when I put my old pair on which has the same strength lens in the left eye, the vision seems crisper.  I have been wearing the Trivex for 5 days now and keep putting my old pair on to compare and they're close but the polycarb seems brighter or crisper.  Also, the AR coating on the Trivex does not seem as "glare free" as the polycarb and I was reading on the internet about Trivex having trouble with AR coatings.  With the Trivex, it seems like I get out of forcused more and have to blink to regain the focal point (which seems strange when the Trivex are supposed to have a "revolving" for lack of better word focal point.
I'm scared to turn these back in and get the same kind I did the last four years (which I believe are Slim Lite Clear (aspheric) from EyeMasters for fear that after I get the new ones, I should have stuck with the Trivex.....

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## shellrob

Did they say why they were putting you in the Trivex to begin with when you didn't have any problems with the polycarbonate?

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## bev

No, The optician just said the Trivex were better and the newest in technology plus lighter lenses and so I thought well, newer, better, ... figuring things were always getting improved on....  I later talked to another optician and he said that I should go back to the store and have the prescription checked for one thing.  I just thought maybe it was something I had to get used to.  I can still read signs in the distance with either pair (bearing in mind the newer pair has the enhanced prescription.) It's like the optometrist saying does this look better or how about this and if I was making the decision at that time, I would have picked the polycarb.  The hard thing is I am comparing the old prescription to the new and in some ways the new is clearer naturally because it has the corrected prescription.  To go on further, I might say the Trivex optics would be softer and the polycarb appears sharper -both being legible.

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## shellrob

Being a person myself that did switch fropm polycarb to trivex, it took me awhile to get used the the change, but I eventually did. It ook about a month...no kidding 

I wonder with your prescription being what it is, why they would recommend trivex over a high index or not to keep you in the poly.......one must wonder....

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## bev

I am glad to hear that you also have the Trivex and that it took you some adjustment.  Please elaborate on why you wonder about my prescription.  What is a high index and if you had my prescription, would poly be better per say?  I just wonder why we have to adjust to the Trivex when I would not have to adjust to the poly?  My whole decision rests on the fact why is the adjustment worth it?  If the Trivex lens is better overall, then should I make the concession to adjust wherein the poly is working for me.  Is there some research done the line that will show staying in Trivex will reduce the need for stronger glasses later on or what?  Thanks.

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## Lewy

You may have already mentioned the problem in one of your postings! Your previous lenses are aspheric? I would guess that the different curves of the lenses, possibly coupled with a different index are the causes of your problems. Your optician will be able to compare the curves using a lens measure.

Lewy

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## bev

Thanks for the useful information. I really appreciate everyone's input.  I am inclined to be a perfectionist with certain things and my vision is very important to me.  I believe the polycarb was aspheric but what really does that mean? I told the optician at that time that I wanted the thinnest lens available at the time and he special ordered it plus with the additional AR treatment, which has been a blessing.  Through the course of time, my eyes are getting worse and I pray they stop changing, at least for that right eye.

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## Laurie

Hi Bev,

Thought I'd jump in here too.

Let's address your problem scientifically...(I am a full time optics instructor...hard to get out of that box)...

Scientifically speaking, TRIVEX has two optical advantages over polycarbonate:

1:  The material's inherent amount of dispersion of light....TRIVEX material has a lower amount of dispersion of light (when light refracts through a material, it disperses...breaking up into its color components, Red, Orange, Yellow, Green, Blue, Violet, Indigo).  (ROYGBIV, if you will).  This is measured in terms of Abbe Value, and, the Abbe Value of TRIVEX is much better than polycarb.

This factor (dispersion of light) cannot be controlled by processing or design...it is inherent in the material.  The lower amount of dispersion of light, the lower amount of Chromatic Aberration.  

Polycarbonate has more chromatic aberration than TRIVEX.  Not everyone is sensitive, to this, however, your Rx indicates that you are likely to notice the difference.

2:  Processing:  

TRIVEX lenses are processed in a similar way to crown glass and CR-39 plastic (still considered optically superior in many ways, however, they have weight/thickness/safety issues).

Crown glass, CR-39 plastic and TRIVEX are ground.  That means that the curvatures are ground away (surfaced) to get the desired optical curves which make up the prescription.

Polycarb consists of tiny little pebbles (like clear b-b's) which are pounded into a mold.  This can result in optical aberrations, and other issues.  And, the amount of chromatic aberration is greater.

Now, for the practical side of things: 

The optician (Lewy) who suggested that it was a base curve, spherical/aspherical issue was right on target.

The difference between a spherical design and an aspherical design is huge.  I would suggest checking the accuracy of the base curves, and wearing a TRIVEX lens with aspherical curves.

There is a simple formula your optician can calculate to verify the correct base curve, or they can contact their lens manufacturer for suggested base curves...the recommended base curves vary depending on prescription, and whether the design is spherical or aspherical.

About as clear as mud?

: )

Good luck, and let us know how it turns out.

Laurie

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## Chris Ryser

> *No, The optician just said the Trivex were better and the newest in technology plus lighter lenses and so I thought well, newer, better, ...*


The old story............also more expensive and profitable. Poeple fall for it and then start doubting the change they made.

Now that you have them...........get used to them.....there is no harm done........you just have to adapt to the little difference of picture your brain perceives and it will adapt as long as Rx and measurments are correct.

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## DaveD

Younger's Trilogy Trivex is only available aspheric. Hoya's Phoenix Trivex is available as aspheric or spherical. So if your in a Trilogy you're in an aspheric.
Augen now manufactures a double aspheric.

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## Pete Hanlin

I would also recommend investigating whether you are currently wearing a spheric or aspheric design lens- since the difference in design is going to have a far greater impact on your vision than any differences in the materials.

If it turns out that you have indeed received aspheric lenses, I would have the fit of the frames investigated. For example, your old lenses may sit slightly closer to your eyes, have a different pantoscopic tilt, or a different amount of "wrap" (aka faceform). Have an Optician compare the fit of your new frames vs. the fit of the old frames.

Regarding Trivex, there is no reason why you should be experiencing difficulty due to the material change. Optically speaking, there is very little difference between the two materials- I personally am unable to discriminate between the two (although I have heard from some who claim they can see a difference that _favors_ Trivex).  In any case, switching from polycarbonate to Trivex should not cause a noticeable decrease in visual comfort- all else being equal.

To sum, your visual discomfort is certainly coming from either a problem with the design of the lenses (aspheric vs. spheric), the fitment of the lenses, or perhaps the fabrication of the lenses (e.g., perhaps waves were introduced into the back side of the lens during grinding).

Good luck with your eyewear.

PS- By way of disclaimer, I am employed by a company that does not manufacture lenses from Trivex.

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## Lewy

Quote: PS- By way of disclaimer, I am employed by a company that does not manufacture lenses from Trivex. 
Yet?

Are we likely to see Essilor introduce Trivex in the near future? At least get rid of the awful Poly.

Lewy

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## bev

Well, thanks for all the input. According to the paperwork (brochure) on my lenses, they are EV 4.0 (brand name of EyeMasters) and it is shown to be aspheric.  The brochure captures an Eagle flying and I assume EV stands for Eagle Vision.????

Anyway,  I was comparing the anti-reflective coating on the Trivex to my poly and lights are casted more in a yellow shade whereas my Polys are white.  The Trivex has stronger images than the Polys.  I still have to try these Trivex out at night and see how the oncoming lights of another vehicle hit me.  Because I can see more of the glare when looking at my glasses in a mirror, there may be some merit to a different tilt of the lenses on my nose as to the polys.  But because the Trivex had a rotating focal point, I did not think the tilt or the distance from my eyes would matter...????

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## shellrob

Just give it some time. Like I said, it took me a good month I think to feel very comfortable with the lenses.

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## Pete Hanlin

But because the Trivex had a rotating focal point, I did not think the tilt or the distance from my eyes would matter...????
Distance from your eyes (vertex distance) will affect any ophthalmic lens- regardless of design or material.
Diminishing the vertex distance (i.e., bringing the lenses closer to your eyes) will improve the optics of your lenses. If you current lenses sit significantly further from your eyes compared to the previous lenses, you will notice a difference.

Pantoscopic tilt (vertical) and wrap (horizontal) will also have an impact on your perception through the lenses. I would take your previous and new eyewear to an Optician and have them compare the fitting characteristics.

The brochure captures an Eagle flying and I assume EV stands for Eagle Vision.????
Various manufacturers (including Essilor) market similar materials under various names. I am unsure who employs the use of the name "Eagle Vision," but speaking from a physiological perspective, the foveas of eagles and humans are structurally distinct. While humans are most likely capable of seeing somewhat better than the traditional "20/20," I don't believe we're going to be competing with eagles anytime soon (which is fine, since we do not have to spot our food from 200' in the air ;^).

Are we likely to see Essilor introduce Trivex in the near future? At least get rid of the awful Poly.
That _awful polycarbonate_ has gained more market share in the US in the past 10 years than any other material. Look, there's nothing wrong with Trivex from a visual standpoint (although the visual difference between an abbe value of 31 and 42 is pretty much nil unless you are looking through a considerable amount of prism).  Its also nice that Trivex can withstand less than optimal drilling processes. However, unless you just can't figure out how to properly drill a lens, there just isn't much reason for the utilization of Trivex. Which is why Essilor doesn't manufacture it... 

As for the future, well- never say never- but I can say I know of nothing in the works.

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## mshimp

Hi Bev,

Some questions I would ask you are the following.
1.Are you wearing a drill mounted frame?
2.Are the edges polished?
3.Are you getting close to the age where you need to wear bifocals?(near 40)
4.Did the optician take a pupil height measurment?

It is my opinion that trivex is only good for drill mounted frames.If this is the case, then you are in the right material.If the edges are polished it will have a very high luster. The highly polised edge could cause more reflections than usual even though they have an anti-reflective coating. Trivex lens are available in aspheric and nonaspheric form. The aspheric design can make the lens thinner as well as "soften" the prismatic effect on the edges (also known as the "fish bowl" effect).Since you power is not that strong the "fish bowl" effect is not that critical.If the lens are aspheric,then pupil height measurements can be an important factor.As mentioned before the frame adjustment should be checked along with verifing that the glasses were made correctly. If you are not in a drill mount I would recommend a differnt material.
Michael

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## bev

As I am a layperson, and not to sound ignorant or naive, if a drill mount is the kind that are drilled into the lenses, no I have a rim all the way around and the lens sits inside the rim.  I will turn 41 in Oct. of this year.  I purchased the same frames as I had with my polys due to liking them and not being able to decide on new frames and having trouble with change.  It was about the same cost to me in either getting new lenses fitted into my old frames or getting new lenses with new frames so I opted for the latter. Why not?  I even weighed the odds of getting just one new lens, since the right eye changed from -3.75 to -4.0.  Also, my right eye was prescribed with a slight astigmatism but I opted not to correct it this year because two years ago I got the prescription for astigmatism and it made me sick and dizzy (but I think the dr. at that time "overcorrected" the astigmatism and I believe he prescribed it for both eyes....)

Anyway, the glasses sit about the same on the nose except maybe a little more distance between the eyes as the tilt on the polys tended to braise my eyelashes on one lens causing me to having to clean it more often due to smudges.  As you can see, I have in one eye an apple to an apple, except for type of lens.  

Yes, the optician marked on the demo pair with a marker the pupil height (if done accurately.)
My fear is if I change back to polys, get the corrected lens for the right eye and then determine - gosh, you saw better with the Trivex as a whole, I will be in trouble.
I can't compare the right lens because it is the new prescription so naturally I see better - in Trivex because that's all I can compare. It's the left lens that is the apple t an apple. What if my two eyes don't want to cooperate together as a whole?

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## shellrob

Bev, how long have you actually been wearing the new glasses?

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## bev

One week on this past Sunday.

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## shellrob

Give it a couple more weeks. A week isn't enough time. Like I said before, it took me 3-4 weeks to adapt. Make sure you don't switch between the 2 pairs.

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## mshimp

Since you are not in a drill mount I would opt out of the trivex. If the trivex lens are not edged ultra perfectly there will be excessive flexing. This flexing and undue stress can cause some blurring in the lens. In regards to your age ,being an emerging presbyope(having some focusing problems when you read through your glasses) That extra .25 increase in the distance may cause problems(usually doctors will not prescribe a +.50 or a +.75 bifocal,but you are there). I would go back to the poly or if you are looking for a better lens consider 1.6 Seiko or 1.6 finalite or the 1.6 called Luscious.These lens materials have high abbe values and low specific gravitys.Meaning it will be light weight,good optics,and better scratch resistance.
good luck
Michael

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## Chris Ryser

> *Since you are not in a drill mount I would opt out of the trivex. If the trivex lens are not edged ultra perfectly there will be excessive flexing. This flexing and undue stress can cause some blurring in the lens. Michael*


I have never heard that a lens mounted on frame with rims can flex.......whatever material...........to disturb any vision of any kind.

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## shellrob

Optically the trixex lens is better than the poly anyhow. Don't rush into switching back quite yet.

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## mshimp

Try this! Take a low power poly or trivex lens(like a -2.00) and cut it to perfect size in a full rim frame on one side.On the other side do the same except leave it a little larger. Look at the lens through a polarscope,then you will see the excessive stress in the lens .This stress can cause distortions in an opthalmic lens.Since trivex "flexes" more than poly the potential for this stress is greater.This unwanted stress can also cause abnormal low abbe values in a given lens.

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## bev

Question: If there were "stress" lines, could that be why I seem to be having more problems with glare like in the true hot sun when the rays are reflecting off chrome and hoods of vehicles.  I do not seem to see this as much with my old lenses (Is that because I am squinting more with the old lenses because they are out of focus and thereby reducing the glare myself?)  I have noticed when I wear the new pair, I open my eyes more and everything is so bright that I want to cup my eyes to avoid the sun.  It is similar to having one's eyes dialated and you see the brightness more.  I tend to be very sensitive to the sun in my older age......  Also, even when lights are on behind me, I will pick up the glare on the inside of the lens as well.  I went to church this weekend and all the lights were shining on my eyes.  It kind of makes it like you were looking at something but a flashlight is shining on you at the same time.  Any ideas?

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## mshimp

Outside in the sun you need a pair of polarized sun lens to cut that kind of glare. Inside ,the kind of glare you are talking about requires an anti-reflective coating.I don't believe the stress we have been talking about has caused any of these problems.

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## Pete Hanlin

Internal stress does not necessarily cause visually detectable aberrations.  It doesn't in heat tempered glass (which has a pattern of stress in the form of a cross), it doesn't in polycarbonate (regardless of what certain manufacturers would love to have you believe), and it wouldn't in Trivex (which as a thermocure resin will not have inherent internal stress).

_Flexure_, which could be caused by an oversized lens, could potentially cause a noticeable visual disturbance (as well as inducing internal stress), but it would have to be severe.  Trivex lenses, like polycarbonate, are very flexible- especially when the overall lens is thin (low powers).   However, the lens would really have to be considerably oversized to cause sufficient flexure to be noticeable.

As to the perceived brightness, that is somewhat surprising, especially since Trivex tends to have a yellowish cast which would theoretically block more light than a polycarbonate lens.

Again, it may well come down to the orientation of the lenses to the eyes.  Unless the lenses have been poorly processed, my guess is that adjustment of the fit should readily resolve the visual disturbances.

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## mshimp

There is no doubt that a heat tempered glass lens has induced stress for greater impact resistance.However I wouldn't compare glass products to plastic products in this way.Glass has superior optics with no flexure.It's like comparing apples to oranges. I'm certainly not recommending glass lens to you Bev. I still maintain my assertion that trivex lens are only good for drill mounts,and maybe rimless frames.This may be one of the reasons why essilor has not shown an interest in this material thus far.This opinion comes after processing hundreds of trivex lens.

Though I do agree with the comments that have been stated in regards to  making sure the frame is adjusted properly and giving it some time.

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## bev

Thank you all once again for all the advice and suggestions.  It really helps.  I talked to my optomestrist who unfortunately has not heard of Trivex.  He told me everyone likes Sushi and he does not.  He said just because everyone likes Trivex and I seem to not is okay.  He suggested I get what I want. Bearing that in mind, for whatever reason, my eyes tend to like the anti-reflective coating on the polys better. Perhaps I got a bad AR on my Trivex???? Still struggling with the decision of what is best for me.  

My 13-year old daughter just got her second pair of glasses (when I got my new pair)and she too got the new Trivex lenses.  Last night she asked me to clean her lenses because there were spots on the lenses (like tiny droplets of hair spray) and they will not come out for the life of me.  I have gotten hair spray out of mine and out of her old glasses which were polycarb as well.  I tried the cleaners I was given and the special cloth, and even used a portable wet wipe and cannot get the spots to go away or even diminish.  Her frames are on the top but rimless on the bottom.  Could these spots be coming from the inside of the lens somehow?  I am already disgusted with Trivex.

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