Can someone explain to me what is Varilux Comfort Short. Is it conventional, enhanced or digital lens?
Confused....
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Can someone explain to me what is Varilux Comfort Short. Is it conventional, enhanced or digital lens?
Confused....
Gavin, welcome to Optiboard. But I have no idea what you just said, could you please restate your post?
Lenny, the Comfort Short was designed along with the Physio Short, to replace the Ellipse.
In general, the Comfort will have wider reading than the Physio, but the Physio wider intermediate. As well, although both are adaptive lenses, the Comfort as the add power increases moves the distortion higher in the lens, up. Keeping the reading wide no matter the add. The Physio adapts differently in higher adds, it will in higher adds shrink the reading a little, and get harder a little, to ensure the distance zone stays wider.
The Comfort Short is available in traditional ground, and digital hybrid. The hybrid designs use the same exact blank, but they have the distance only digitally processed into the back. It was called the "360" but is now the "Enhanced". The reading and intermediate zones are still cast on the front.
Thanks, but still confused!
Does comfort short uses a regular comfort blank?
No. Separate blanks.
It's conventionally surfaced but they call it 'digital' to fool people into thinking it's 'freeform'. Any lens that can come uncoated is not freeform, at least in my understanding, so if it's a conventional PAL it must use different blanks for different corridor lengths.
I don't think there are Comfort Short blanks....
Can someone come up with a SQU?
Comfort and Comfort short use the same blanks. The traditional comfort has a just the distance surfaced into the back side so the add is all from the set corridor length on the front surface of the lens. The comfort short utilizes a deformed conicoid surface ont he back to achieve a bump in power which when combined with the front surface corridor decreases the viewing angle required to achieve a higher add power in the lens.
Think of it like this, it's like putting a digital version of the anti-fatigue ont he back of a traditional Comfort. This technology could be used on any PAL design, but in the comfort they optimized the back surface design to compliment the front surface addition.
Clearly I was wrong, so my apologies. I wasn't aware of a technique like the one PhiTrace described. Thanks PhiTrace.
Don't get caught up with the term conicoid, its just a description I use for the deformed back surface. As with any short corridor lens if the near is moves higher the intermediate is compressed. That compression doesn't necessarily mean unusable. The varilux lens uses a traditional elephant trunk design and gets harder as the corridor is shortened.
So this looks like same thing we used to do...
Add a 0.25 to add if the fitting height is 1-2mm too low!