Comfort = Natural?

[HarryChiling]

Sounds more like they're just very similar designs... how can they be the same... but different?

On a side note, the article made me giggle a bit.. the brand new Adaptar heh

I guess same type of lens would have been a more accurate explanation, but you get the idea. If that consistutes a new lens then you could take any lens design tweak it a little and call it different. It's not like the desingers started with a blank slate and built up or even took an existing design and improved it, they just changed a variable to make a lower cost product to appeal to a wider market. All that said our office uses the Natural as our house lens and it works great.

[MarcE]

All that said our office uses the Natural as our house lens and it works great.

Considering this with respect to your previous statement regading a longer corridor length for Natural vs Comfort (even though both have a recommended MFH of 18mm). Do you see any issues when fitting the Natural at the MFH of 18mm? How about 17mm?

As far as "house" lenses go, I have SOO many FH of 17 - 18mm, that I use the Ovation. Is it my frame selection that warrants a majority of shortish fits?

[HarryChiling]

I have not hd any problems with fitting the seg heights as low as 18mm, but if the add is +1.70 or above then I go short corridor and our house for that is the compact.

We also stock

Progressives

1. Natural
2. Compact

Ocupational

1. Zeiss Buisness
2. Sola Contiuum

Single Vision Finished

1. True Tints
2. Gentex
3. Gentex w/AR

Single Vision Semi Finished

1. Transitions (Grey and Brown)
2. ASL
3. Sola SFSV
4. Seiko 1.67
5. Younger Nupolar (Grey and Brown)

Bifocals

1. Sola FT28

That just about does it, I love carrying the SFSV as it expands our stock without a great investment finished lenses require.

[AdmiralKnight]

Working for Sears, we had the exact same lens scheme as Pearls do. Natural being used as the bread and butter lens, the ovation if you needed a 17, and the compact for the 15/16 heights.

Honestly, its hard for me to know if there were any issues with the Natural. We didn't have to many people coming back, but I guess the problem lies in whether or not the patients could have been seeing better or not, with a different, newer lens.

[Darryl Meister]

While Essilor's site is attempting to differentiate the two in a non-technical way, Comfort and Natural are indeed two different lens designs:

[HarryChiling]

While Essilor's site is attempting to differentiate the two in a non-technical way, Comfort and Natural are indeed two different lens designs:

Nice images, but I thought we were not supposed to draw any conclusions from lens maps? In this case the text contradicts the images you have up here. One does look harder than the other, but essilor is telling us something different. I sure wish opticians had a more objective way of lookign at these lens (hint hint).

[Darryl Meister]

Nice images, but I thought we were not supposed to draw any conclusions from lens maps?

Nevertheless, you can at least tell that they're two different lenses. ;)

In this case the text contradicts the images you have up here. One does look harder than the other, but essilor is telling us something different.

Not really. The link you provided states, "Essilor Natural is a lens which has many of the attributes of Varilux Comfort..." This isn't saying that the two lenses are the same (or even similar, for that matter); it's simply saying that they share some common features or performance aspects.

[HarryChiling]

They say that the corridor is longer on the Natural, but when you superimpose the two images you provided the markings remain the same, yet the map is different? Also the maps show the PRP and DRP on the line, both comfort and natural are 4 up. I don't want to give you a hard time Darryl, but those images are not necessarily what I would refer to as conclusive evidence. That's why I ask for consistent maps on all lenses so that they can be compared without having to worry about skewed data or images that don't jive.

[Darryl Meister]

They say that the corridor is longer on the Natural, but when you superimpose the two images you provided the markings remain the same, yet the map is different?

Yes, you can confirm for yourself that the near reference point location of both Essilor Natural and Varilux Comfort is around -14 mm from the PRP. This is also the same near reference point location used for Essilor Adaptar, Varilux Panamic, Varilux Liberty, etcetera. Corridor length is typically defined differently than the distance to the near checking circle, although the two are subtly related, of course.

Also the maps show the PRP and DRP on the line, both comfort and natural are 4 up.

The horizontal line is simply a reference line I add to my plots at the level of the fitting cross. Since the horizontal reference lines for progressive lenses vary anywhere from 0 to 6 mm below the fitting cross, having a standardized location makes for more consistent comparisons when analyzing these lens plots.

I don't want to give you a hard time Darryl, but those images are not necessarily what I would refer to as conclusive evidence.

Well, they sure look like different lens designs to me... Is it that you think the two plots still look too similar to be different lens designs?

That's why I ask for consistent maps on all lenses so that they can be compared without having to worry about skewed data or images that don't jive.

The maps were produced using identical methods. They have not been altered in any way. The most statistically representative plot was determined from ten measured lenses, each with a +2.00 addition. In any event, the purpose of posting these two plots was simply to demonstrate that they are in fact different lens designs, not really to communicate any other technical details or design features.

[HarryChiling]

It's really only the distance that looks different, the readin and corridor look almost identical, the distance on the comfort looks harder than the natural. I am curious if the older Varilux was similar to the Natural, and why then use the doule talk that the lens shares similar features, but the natural requires "greater ocular muscle effort to reach 85% of the add", that's not what the map shows, the bottom portion of the lens is in the same place and the inset from the map looks the same. Am I missing something? The distance is different and the periphery in the intermediate is different.

[AdmiralKnight]

They look similar to me. Not the same, but close. There are obvious differences though. The corridor on the natural is a bit wider at the intermediate. The reading area looks quite similar, but there are definate differences in the distance.

[Darryl Meister]

After evaluating progressive lenses for a while, you eventually develop more of a familiarity with the overall "fingerprint" of a given brand, as well as how to discriminate various characteristics of the lens design by sight.

Essilor Natural, for instance, has relatively horizontal lobes of unwanted astigmatism in the periphery, with rounder distance and near zones. The width of the lower near zone, to the 1.00-diopter cyl contours, is fairly wide, and the near periphery is slightly softer. The progressive corridor is also slightly wider on average. You can also observe that there is a wider entry into the progressive channel, with less unwanted power in the vicinity of the fitting cross. This will open up the central distance zone a little, while reducing the sensitivity of the lens design to small fitting errors. However, there is obviously more unwanted astigmatism in the periphery of the distance zone.

Varilux Comfort, on the other hand, has more vertically-oriented lobes of astigmatism, resulting in a more funnel-shaped near zone and astigmatism that pulls down, not up, in the periphery of the distance zone. Although the peak astigmatim level is basically the same, this more vertical orientation will result in lower levels of skew distortion (i.e., cylinder at axis 045) and image swim moved from the distance periphery to the near periphery. Although the near zone is not quite as wide, you can observe that the near zone of Varilux Comfort has been pulled up slightly, which will make it more accessible. The add power along the umbilic of the near zone is also more vertically stable in this design.

[Barry Santini]

Varilux Comfort, on the other hand, has more vertically-oriented lobes of astigmatism, resulting in a more funnel-shaped near zone and astigmatism that pulls down, not up, in the periphery of the distance zone. Although the peak astigmatim level is basically the same, this more vertical orientation will result in lower levels of skew distortion (i.e., cylinder at axis 045) and image swim moved from the distance periphery to the near periphery. Although the near zone is not quite as wide, you can observe that the near zone of Varilux Comfort has been pulled up slightly, which will make it more accessible. The add power along the umbilic of the near zone is also more vertically stable in this design.

Darryl:

These Comfort Qualitys of vertically-oriented astigmatism and a good DV periphery, with a near zone that is "pulled up", seems similar to the advantages attributed to Physio, and explains the 22mm vs. 18mm fitting utility of Comfort.

Barry

[chip anderson]

You have relieved a long standing question from my mind explaining what Zulu ment. I had asked untold numbers of servicemen (since I hear and saw it on JAG all the time) and non of them had a clue. I had thought it was a service or at least a common naval term.

Little things like this worry me a lot but I don't have the time or am too lazy to look all this stuff up like you and Rieslberg.

Chip