Originally Posted by
Pete Hanlin
Are these Physio Enhanced studies independent as well?
Yes, they are. In the interest of full disclosure, I'll try to describe what I mean by independent (and leave it up to the reader to decide if the term is accurate).
When we conduct a clinical study, we contract with Schools of Optometry and/or other organizations which test ophthalmic products. Essilor funds the study, and reviews the study protocols- but the organization conducting the clinical procures the lenses and conducts the study.
When I say "reviews the protocols," I mean we ensure the testing is being conducted in a double-blind, randomized environment, with a population which is representative of the population as a whole (for most tests, sometimes we want to test a specific population- for example on polarization, we may want to specifically test pseudophakes). We have had outside organizations review our clinical testing protocols as well, which has resulted in further independent certification of the protocols.
"Double-blind" means neither the subject nor the examiner knows the identity of each product being tested (two pair of identical eyewear- the only difference is one has a small dot in the inside of the hinge... there is an assistant that knows which lens is which for recording purposes, but s/he does not interact with the subject). "Randomized" means the order in which the products is varied (further removing the possibility of the subject/examiner knowing which product is which, and also removing "order bias" from the subject).
Once the study is conducted, the organization provides an analysis of the results to Essilor. In the vast majority of cases, we grant permission for the organization to publish articles or posters on their findings- in many cases, I create "posters" which summarize the results. In other cases, the study may have been comparing developmental products (in which case, the results are sent back to Essilor R&D, which conducts even more tests than we do as part of the lens design process).
Conducting a clinical study is an expensive endeavor. For example, to remove as many variables as possible, we have to make sure all of the lenses a.) are made of the same material, and b.) have the same or similar AR treatment. The only material most competitors have in common is 1.67, so we usually end up ordering 80 pair of 1.67 w/AR PALs for the subjects. Usually you shoot for 40 or so subjects- knowing you need at least 30 subjects to acheive statistically significant findings (p-value of <0.05), and some subjects will "drop out" (for one reason or another, they will either not show for the visits or have a condition which excludes them from participation- such as an eye condition). Then the subjects have to be examined, fit with identical frames, and scheduled for the evaluations.
Anyway, when clinical tests are conducted between products in this environment, we are often able to acheive statistically significant results (i.e., one product is DEFINITELY favored over another- either globally or in certain aspects). Other times, we find there is very little difference in the performance of two products.
If I'm less than overwhelmed with some of the FBS digital products on the market, its because I've had them tested against traditional designs and have found that DESIGN has a much larger impact on product performance than the PROCESS used to make the lens. There are several FBS designs which do not perform as well as traditionally processed designs. Of course, I focus mostly on Varilux products- but I would suspect traditional Zeiss & Hoya lenses would also perform better than some of the "FBS designs" on the market today.
Main point to all this is as follows- the claimed "benefits" of FBS processing (keyhole effect, greater accuracy, and supposed reduction of peripheral distortion) do not appear to make an impact on the actual vision of real human subjects (which is what it all comes down to). For example, during a comparison of an FBS design to Varilux Comfort, a majority of subjects found Varilux Comfort to be wider in every zone compared to the FBS design (not to a level of statistical significance, but by a clear majority). I'm saying this- if you take a traditional design and move it to the back surface, you will not find a difference in the performance of the design in a clinically controlled environment. For all the hype about "full-back surface" benefits, they just don't pan out in real life (which is what I suspect practitioners will discover as they dispense more and more of these lenses).
Sorry for the length, but my involvement in the testing process over the past few years has really shed a lot of light on what makes a PAL "tick." I know digital surfacing sounds really cool- but its just another way to make a lens. That's not to say digital surfacing can't be used to create certain design elements which have significant impact (example, when Varilux 360 products are compared to non-360 products, we can measure improvements in performance with the 360 products), but digital surfacing alone just doesn't seem to make much difference in how a PAL performs.
Bookmarks