Trouble with New Trivex Lenses
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.
TRIVEX or POLY, Spherical Vs. Aspherical
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
Adapt............................
Quote:
Originally Posted by 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, ...
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.
Lense do not flex..........................
Quote:
Originally Posted by 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. Michael
I have never heard that a lens mounted on frame with rims can flex.......whatever material...........to disturb any vision of any kind.