Children with high RX?

[DragonLensmanWV]

Trivex is a brand name on patent, correct? How long will it be before it goes off patent and is available as own brand from other manufacturers?

Our only choice is high index. I'd rather do Trivex, but it's not available to us.

Actually, Trivex is the material. Other manufacturers have their own name for it, like Younger's Trilogy, Hoya's Phoenix, etc.
http://corporateportal.ppg.com/NA/ch...ptical/Trivex/

[chip anderson]

Trivex and Phoenix are both trade names for (I think) polyethlene. Same stuff rollerskate wheels are made of.

Chip

[DragonLensmanWV]

Trivex and Phoenix are both trade names for (I think) polyethlene. Same stuff rollerskate wheels are made of.

Chip

That's polyurethane.And it's a close cousin to 1.60.

[chip anderson]

The Dragon is correct. Funny how one can have trouble with things like this when one gets old.
Odd, that it's one of the cheapest plastics around when it's used for stuff like plastic hammer heads.
Lots cheaper than poly and plexiglass.
Chip

[tigerlilly]

I was trying to find out why we don't have it, and I was told that it's not available to us. Since our lenses are virtually all in house rather than buyouts, I was led to believe it was a patent issue. Hmm. I was also told Trivex is very expensive.

So, now that I'm all confused, which is it? Polyethylene or polyurethane?

[harry a saake]

To answer the original question, i dont know of any state laws in any of the 6 states i am licensed in or have been licensed in. One as an optician, and that is why you are an Optician, is to make a sound judgement when ALL considerations are taken into account.

The very idea that all kids HAVE to have poly, trivex, glass ,cr-39 or any thing else for that matter, is a step in the wrong direction right off the bat. This shows you are not considering circumstances.

Now some of us are stuck with company rules that will dictate the use of poly, no matter what, thats something you have to live with or get another job.

The biggest problem from all of this has nothing to do with optics whatsoever. The problem is we have a very litiguous society today that loves to sue, and could care less if they ruin your life and livelyhood.

The other part of this problem is it does not matter at all, what material you use. if for some reason that lens breaks and does any kind of permanent damage, you are in trouble or may be.

There has been a lot of talk, facts, figures about poly over the years about, its the best for impact resistance, that part is true IMPACT!! only! actually a piece of poly with steady pressure will crack rather easily, proof of the is all your drill mounts that are always cracking, slow steady pressure, so it,s concievable that a kid could possibly have this happen, maybe with an airbag as example.

So what is best, what the situation dictates, a kid with reading only glasses of +.75 probably does not need poly, a kid playing sports such as baseball, should not only be in poly but a rec spec ground 3.0 at thinnest point. As Chip pointed out, and more especially for thes kids with correction in one eye only, antimetropia, anisekonia etc contacts are a good viable way to go as long as they can be fit and today most of them can. I have successfully fitted boys as young as 8 without a problem, as long as you keep in mind that not everyones a good candidate

What it boils down to is you need to do your homework and spend more time with these kids to really determine what will be best.

As far as protecting yourself legally, you need to talk to your local attorney about forms etc, but when you really think about it is there any difference between kids and adults, should you not use the same logic for both?

[shellrob]

Ok, how about a +8.00 in a 2 year old in a size 43 frame with a 48 pd. I wanted to go high index but the doctor I work for says no. I see that pretty much any lens in this rx will pass the drop ball test???? Am I wrong to want to put this pt in a high index or will it really matter at this point???

[john-atlanta]

Ok, how about a +8.00 in a 2 year old in a size 43 frame with a 48 pd. I wanted to go high index but the doctor I work for says no. I see that pretty much any lens in this rx will pass the drop ball test???? Am I wrong to want to put this pt in a high index or will it really matter at this point???

I dont consider myself to be on the Trivex bandwagon, but if there were a case to be made for it, this would be it! Why, you ask?

Well, most 2 year olds are not that concerned about how the glasses look, but rather how they *feel*.

Thanks to the awesome work of the guys at OptiCampus, we can see that Trivex has the lowest specific gravity, so it should be the lightest pair. Also, the higher the Rx, the more important ABBE is, so Trivex is a good choice there too, especially with the low specific gravity. Me, I would put AR on an Rx this high, regardless of the patients age

Finally, it is a safe choice in this litigiousness society we live in.

If there is a huge amount of decentration, digital surfacing may want to be considered like the Auto II SV in Trivex.

[drk]

Issue One:
Just because specific gravity Trivex < specific gravity polycarbonate doesn't mean the Trivex finished product will be lighter.

You have to consider mass. The poly lens will be thinner as a higher index.

You have to consider asphericity value. The poly lens could be more aspheric thus flatter.

Now, I'm not saying Trivex wouldn't be the better choice, but we don't have all the information.


Issue Two:
What does decentration have to do with digital surfacing? Isn't traditional surfacing equally good in this case?

Issue Three:
Shellrob, your OD is trying to be litigation-smart, not safety-smart. He/she must feel that if isn't Trivex or poly, then (regardless of the actual safety of the lens) there's liability. Screwed up lawyers.

Issue Four:
Shellrob, index isn't as important as frame selection, good craftsmanship, and asphericity in high plus. I would agree that weight is an important consideration.


Please correct me if I'm wrong on any of this.:cheers:

[DragonLensmanWV]

Issue One:
Just because specific gravity Trivex < specific gravity polycarbonate doesn't mean the Trivex finished product will be lighter.

You have to consider mass. The poly lens will be thinner as a higher index.

You have to consider asphericity value. The poly lens could be more aspheric thus flatter.

Now, I'm not saying Trivex wouldn't be the better choice, but we don't have all the information.


Issue Two:
What does decentration have to do with digital surfacing? Isn't traditional surfacing equally good in this case?

Issue Three:
Shellrob, your OD is trying to be litigation-smart, not safety-smart. He/she must feel that if isn't Trivex or poly, then (regardless of the actual safety of the lens) there's liability. Screwed up lawyers.

Issue Four:
Shellrob, index isn't as important as frame selection, good craftsmanship, and asphericity in high plus. I would agree that weight is an important consideration.


Please correct me if I'm wrong on any of this.:cheers:

Here's something you should read concerning the weight of Trivex and how it relates to other lenses, thinner or thicker.
http://www.youngeroptics.com/pdf/tri..._Monograph.pdf

[allanon]

I don't have any issues putting a kid in trivex, poly, or 1.67. My only concern with Trivex is far-fetched at best. There has yet to be a product liability case concerning a juvenile in Trivex. You would win, but being the first is never good.

For me, contact lenses all the way with significant anisometropia. I have a 5yo now that's -5sphere in one eye, plano-ish in the other. His parents opted for 30day EW. The parents were trained but prefer us to handle it.

[drk]

Very nice post, WV.

I guess the mass/weight offset effect kicks in at 12D. The numerical difference between 1.53 and 1.59 is apparently not as significant as the difference between 1.11 and 1.21 until then. I would have thought it'd kick in at lower powers.

I also wonder if the mass-reducing effects of asphericity is linear...that is, is aspherizing a higher-index lens more effective at reducing weight than aspherizing a lower-index lens? This analysis was with spherical lenses. I suspect that Trivex's weight advantage would decrease sooner than 12D.

I also note that the weight difference is maximal compared to 1.67 in the -3.00 to +6.00 power range, but the effect is only 10-15%. How much less of a weight difference is Trivex than poly in this range? They only say "lighter". One half of one percent lighter? Who knows?

[allanon]

Ok, how about a +8.00 in a 2 year old in a size 43 frame with a 48 pd. I wanted to go high index but the doctor I work for says no. I see that pretty much any lens in this rx will pass the drop ball test???? Am I wrong to want to put this pt in a high index or will it really matter at this point???

You could probably drop Fezz's oversized stein on that lens and nothing would happen, even in a 1.54. As Harry pointed out earlier, it's the litigious nature of pediatrics that has your doc's tail between his/her legs. It's also likely a bit ignorant. If you can drill it, it's probably safe. Your doc also knows that you almost always lose product liability suits.

Our policy is trivex, poly, or 1.67 for anyone under 18. I have waivers for lots of things (off-label meds, foreign body removal, even old frame repair), but I think the safety of an eye is worth paying for. If a parent won't spring the extra $20 for poly, then they can have an awesome day somewhere else. We've never had a parent walk, but the sales approach isn't as blunt.

Fresh out of school, I used to write poly only on my scripts (pre trivex, pre experience). I now write poly only unless consent and I document the chart as "Rx MR, poly+".

[john-atlanta]

You could probably drop Fezz's oversized stein on that lens and nothing would happen, even in a 1.54. As Harry pointed out earlier, it's the litigious nature of pediatrics that has your doc's tail between his/her legs. It's also likely a bit ignorant. If you can drill it, it's probably safe. Your doc also knows that you almost always lose product liability suits.

Our policy is trivex, poly, or 1.67 for anyone under 18. I have waivers for lots of things (off-label meds, foreign body removal, even old frame repair), but I think the safety of an eye is worth paying for. If a parent won't spring the extra $20 for poly, then they can have an awesome day somewhere else. We've never had a parent walk, but the sales approach isn't as blunt.

Fresh out of school, I used to write poly only on my scripts (pre trivex, pre experience). I now write poly only unless consent and I document the chart as "Rx MR, poly+".

Does anyone have a source for a standard impact resistance for the various materials? This video demonstrates the tensile strength of various materials and shows 1.60 to be the best. Yet no one has mentioned 1.60 in this thread. Does it have poor impact resistance?

Does the aforementioned video mean that 1.60 is the best choice for drill mounted lenses? It scored higher than trivex, so why would one choose to drill trivex before 1.60?

Thanks!

John

[drk]

Yeah, but whose 1.60? All the lab-based numbers and statistics are less than 100% useful. AR coating affects impact resistance, etc. etc.

I think the best way to determine what is "drillable" is to talk to your lab. They'll have a feel for what they like to use based on experience, not lab studies.

As to impact resistance, who REALLY cares? I mean, we want "safe" lenses for kids and all, but there was not a rash of blind eyes in the glass era.

What we need to do is not fret about 1.60's COLTS ratings vs. 1.67's, but about doing due dilligence because of torts. It's not science, but politics.

[Chris Ryser]

1) A kid that the kid age will have the frame crooked on his face within the first week. And then again week after week.

2) The lenses will be scratched within the same time span. So any expensive lenses will be for the birds because after they are terribly scratched you will have to replace them anyhow.

3) So forget the aspheric designs, and the AR coatings and other bells and whistles. Let him have a simple CR39 lens thick enough so that a car can run over it without breaking them, make nice hidabevel so the thickness wont show and the lenses can be popped back in by the parents when he manages to squeeze them out.

4) Find the least expensive way to go because this will be a eternal repeat customer that will be buying, or given 2 to 3 pairs per year at least, unless you give a full warranty which might cost you your lively hood at the end.

5) See that he gets a good strong plastic frame and a saddle bridge, with riding bow temples if you can get it. No metal frame with nose pads as you might get sued for damaging his nose when the arms get out of shape and the pads cut into the nose flesh.

[RT]

Does anyone have a source for a standard impact resistance for the various materials? This video demonstrates the tensile strength of various materials and shows 1.60 to be the best. Yet no one has mentioned 1.60 in this thread. Does it have poor impact resistance?

There are several materials whose index of refraction, when rounded off to 2 decimal points, is 1.60. They have very different properties, including impact resistance.

Impact resistance is further complicated in that some factory or lab applied coatings (including sratch and AR coats) can affect impact resistance. In many cases, application of coatings will decrease the lens' impact resistance, but it can vary depending on a lot of things. Some AR coats use a "cushion coat" or "double coat" that increase impact resistance. That's why some labs can offer 1.0 center thickness on 1.60 or 1.67, and other labs can't. So impact resistance for the exact same product could vary from one lab to another.

Ultimately, in the US, the FDA dropball procedure is the referee test for impact resistance, and the lab is repsonsible for ensuring compliance.

As to impact resistance, who REALLY cares? I mean, we want "safe" lenses for kids and all, but there was not a rash of blind eyes in the glass era.

Are you channeling Chip? You can't possibly believe this. Remember the days when you weren't supposed to hit a kid wearing glasses? These days, I feel OK about punching everyone, regardless of their eyewear.

[chip anderson]

I'm prettyk much with Chris other than I would get regular temples and do a conversion to cable with Hilco coversion as you can do custom lenghening this way and the will be replacable when they get chewed up or whatever.
Not to mention that Riding Bow isn't going to be available (very few manufactures will even know what one is if you ask) on very much today.

Chip